Cognitive Psychology
lateral inhibition
-the capacity of an excited neuron to reduce the activity of its neighbors -inhibition that is transmitted across the retina -more inhibition=decreased response--->cells fire less---->appear darker
likelihood principle
A corollary of the theory of unconscious inference, which states that we perceive the object that is most likely to have caused the pattern of stimuli we have received.
Ames room
A distorted room which creates an erroneous perception of the sizes of people in the room. The room is constructed so that two people at the far wall of the room appear to stand at the same distance from an observer. In actuality, one of the people is much farther away than the other.
precueing
a procedure in which participants are given a cue that will usually help them carry out a subsequent task. This procedure has been used in visual attention experiments in which participants are presented with a cue that tells them where to direct their attention. -the experiments showed that participants performed better on valid trials (where the arrow was pointing the right direction of the upcoming stimulus) than on invalid trials (where the arrow was pointing in the direction opposite the upcoming stimulus)
algorithm
a procedure that is guaranteed to solve a problem.
pupil
The adjustable opening in the center of the eye through which light enters. -looks black because of diffusion but flashes reveal the blood vessels (red eye)
color constancy
The effect in which the perception of an object's color remains constant even when the wavelength distribution of the illumination is changed. Approximate _________ means that our perception of color usually changes a little when the illumination changes, though not as much as we might expect from the change in the wavelengths of light reaching the eye.
peripheral retina
The entire retina besides the fovea. Contains both rods and cones, but many more rods than cones. -Greater number of receptors converge into ganglion and bipolar cells than they do in the fovea.
problem of figure-ground segregation
The question of what causes perceptual segregation. When we see a separate object, it is usually seen as a figure that stands out from its background, which is called the ground. -The figure appears to be shaded differently (darker/brighter) than the ground. -Contours belong to the figure - not to the ground. -The figure is seen "in front" -The ground seems to extend behind
dark adapted sensitivity
The sensitivity at the end of dark adaptation -is about 100,000 times greater than the light-adapted sensitivity measured before dark adaptation began.
cast shadow
The shadow thrown by a form onto an adjacent or nearby surface in a direction away from the light source. -gives relative distance information
Purkinje shift
The shift from cone vision to rod vision that causes the enhanced perception of short wavelengths during dark adaptation.
retinitis pigmentosa
a degeneration of the retina that is passed from one generation to the next (although not always affecting everyone in a family) -this condition first attacks the peripheral rod receptors and results in poor vision in the peripheral visual field. Eventually, in severe cases, the foveal cone receptors are also attacked, resulting in complete blindness.
Stroop effect
a demonstration of interference in the reaction time of a task. When the name of a color (e.g., "blue," "green," or "red") is printed in a color not denoted by the name (e.g., the word "red" printed in blue ink instead of red ink), naming the color of the word takes longer and is more prone to errors than when the color of the ink matches the name of the color.
shadow
a depth cue that can help determine the location of objects
absolute disparity
a difference in the actual retinal coordinates in the left and right eyes of the image of a feature in a visual scene -it provides information about the distances of objects. The amount of ______ indicates how far an object is from the horopter. Greater disparity is associated with greater distance from the horopter. - it changes every time the observer changes where he or she is looking.
Capgras's Syndrome
a disorder in which a person holds a delusion that a friend, spouse, parent, or other close family member has been replaced by an identical-looking impostor. -Certainty that familiar people, relatives or friends, have been replaced by a duplicate, a robot, an alien or an impostor. -Able to recognize the identity of a familiar face but deny the "authenticity" of such a face. -When recognition of the visual appearance is accompanied by an altered emotional response, It causes an impairment of the ability to identify a face as familiar.
Ishihara plate
a display of colored dots used to test for the presence of color deficiency. The dots are colored so that people with normal (trichromatic) color vision can perceive numbers in the plate, but people with color deficiency cannot perceive these numbers or perceive different numbers than someone with trichromatic vision
apperceptive agnosia
a failure to understand the meaning of objects due to a deficit at the level of object perception -Characterized by nearly perfectly intact visual ability Basic sensory level, But cannot form a visual percept of the object.
ROC curve (receiver operating characteristic)
a graphical plot which illustrates the performance of a binary classifier (signal or noise) system as its discrimination threshold is varied -shows that factors other than sensitivity to the stimulus determine a person's response
vitreous humor
a jellylike substance that fills the inside of the eye
retinotopic map
a map in which each point on the LGN corresponds to a point on the retina -The correspondence between locations on the retina and locations on the LGN means that neurons entering the LGN are arranged so that fibers carrying signals from the same area of the retina end up in the same area of the LGN, each location on the LGN corresponds to a location on the retina, and neighboring locations on the LGN correspond to neighboring locations on the retina.
visual search
a method in which the observer's task is to find one stimulus among many, as quickly as possible.
additive color mixture
a mixture of lights. If light A and light B are both reflected from a surface to the eye, in the perception of color the effects of those two lights add together -involves adding up the wavelengths of each light in the mixture -where the two spots are superimposed, the light from the blue spot and the light from the yellow spot are still reflected into the observer's eye. The added-together light therefore contains short, medium, and long wavelengths, which results in the perception of white. -"Primary" colors of light are blue, green and red. Mixed together, these primaries form white.
texture gradient
a monocular cue for perceiving depth; a gradual change from a coarse distinct texture to a fine, indistinct texture signals increasing distance. objects far away appear smaller and more densely packed
relative height
a monocular cue for perceiving depth; objects higher in our field of vision and are below the horizon are perceived as farther away -When objects are above the horizon, like the clouds, being lower in the field of view indicates more distance.
relative size
a monocular cue for perceiving depth; when two objects are of equal size, the one that is farther away will take up less of your field of view than the one that is closer.
deletion and accretion
a motion-produced cue wherein as an observer moves sideways, some things become covered, and others become uncovered. -are related to both motion parallax and overlap because they occur when overlapping surfaces appear to move relative to one another. They are especially effective for detecting the differences in the depths of two surfaces
motion parallax
a motion-produced depth cue in which the relative movement of elements in a scene gives depth information when the observer moves relative to the scene -as we move, nearby objects appear to glide rapidly past us, but more distant objects appear to move more slowly. Thus, when you look out the side window of a moving car or train, nearby objects appear to speed by in a blur, whereas objects on the horizon may appear to be moving only slightly. -objects that are farther away will "move with us" in the same direction
FMRI
a neuroimaging technique that is based on the measurement of blood-flow -indicates the presence of brain activity because the hemoglobin molecules in areas of high brain activity lose some of the oxygen they are transporting. This makes the hemoglobin more magnetic, so these molecules respond more strongly to the magnetic field.
unilateral dichromat
a person with trichromatic vision in one eye and dichromatic vision in the other
absorption spectrum
a plot of the amount of light absorbed by a substance versus the wavelength of the light. -the rod pigment absorbs best at the blue-green area of the spectrum -there are 3 _____ for cones because there are three different cone pigments, each contained in its own receptor.
size constancy
a principle states that our perception of an object's size remains relatively constant, even when we view an object from different distances, which changes the size of the object's image on the retina.
belongingness
a principle that states that an area's appearance is influenced by the part of the surroundings to which the area appears to belong. -explains White's illusion
positron emission tomography (PET)
a procedure in which a person is injected with a low dose of a radioactive tracer that is not harmful. The tracer enters the bloodstream and indicates the volume of blood flow. The basic principle behind the __ scan is that changes in the activity of the brain are accompanied by changes in blood flow, and monitoring the radioactivity of the injected tracer provides a measure of this blood flow.
behaviorism
an approach to psychology that emphasizes observable measurable behavior -Internal thoughts and ways of thinking = speculation -We can not say anything meaningful about cognition -Method: Animal experiments, conditioning experiments Observing and measuring Stimulus-Response relations (stimulus=independent measure)(response=dependent measure) -Linguistic arguments against behaviorism: Children can produce novel sentences they never heard (A cognitive algorithmic structure underlying language)
extrastriate body area
an area in the temporal lobe that is activated by pictures of bodies and parts of bodies, but not by faces or other objects
superior colliculus
an area involved in controlling eye movements and other visual behaviors that receives about 10 percent of the fibers from the optic nerve
fusiform face area (FFA)
an area located in the fusiform gyrus on the underside of the brain directly below the inferotemporal cortex -specialized to respond to faces
structuralism
an early school of psychology that used introspection to analyze mind perceptions into their constituent components -One of the basic ideas behind this approach was that perceptions are created by combining elements called sensations (just as each of the dots in the face in Figure 5.9 add together to create our perception of a face)(p. 104)
illumination edge
an edge where the lighting itself changes (having nothing to do with the objects themselves)
reflectance edge
an edge where the reflectance of two surfaces changes. -may change because 2 objects are made of different materials that reflect different amounts of light
simultaneous color contrast
an effect that occurs when surrounding an area with a color changes the appearance of the surrounded area. -explains the effect of afterimages
Cytochrome oxidase
an enzyme on the hypercolumn that responds to color
striate cortex
another name for the primary visual receiving area because of the white stripes that are created within this area of cortex by nerve fibers that run through it -more than 80 percent of the cortex responds to visual stimuli -good acuity is associated not only with sharp focusing of images on the retina, and the small amount of convergence of the cones, but also with the relatively large amount of cortical area devoted to the all-cone fovea. -the cortex is organized into a number of different kinds of columns.
amacrine cells
cells in the retina that connects and is responsible for input from bipolar cells and ganglion cells -receive information from bipolar cells and send it to other bipolar, ganglion or amacrine cells. -control the ability of the ganglion cells to respond to shapes, movements, or other specific aspects of visual stimuli.
bipolar cells
cells in the retina that exist between photoreceptors (rod cells and cone cells) and ganglion cells. They act, directly or indirectly, to transmit signals they receive from the photoreceptors to the ganglion cells. -receive information from photoreceptors and horizontal cells
horizontal cells
cells in the retina that help integrate and regulate the input from multiple photoreceptor cells. They allow the eyes to adjust to see well under both bright and dim light conditions. -sum the activity of photoreceptors from the surrounding area -have the opposite influence on the bipolar cell to that of the photoreceptors that project to it.
simple cortical cells
cells in the striate cortex with receptive fields that, like center-surround receptive fields of neurons in the retina and LGN, have excitatory and inhibitory areas. However, these areas are arranged side by side rather than in the center-surround configuration -Respond best to a stimulus with a particular orientation and location
ganglion cells
cells located near the inner surface of the retina that receive visual information from photoreceptors via two intermediate neuron types: bipolar cells and amacrine cells. They transmit visual information from the retina to several regions in the brain through the optic nerve
end-stopped cells*
cells that fire to moving lines of a specific length or to moving corners or angle (Figure 4.8b shows a light corner stimulus that is being moved up and down across the retina. The records to the right indicates that the neuron responds when the corner moves upward. The neuron's response increases as the corner-shaped stimulus gets longer, but then stops responding when the corner becomes too long)
location columns
columns in the striate cortex that are perpendicular to the surface of the cortex so that all of the neurons within a column have their receptive fields at the same location on the retina. -Columns contain neurons that interconnect, but are not sensitive to activity in parallel columns
orientation columns
columns in the striate cortex, each of which contains cells that respond best to a particular orientation (respond to lines of the same angle.) -Columns contain neurons that interconnect, but are not sensitive to activity in parallel columns
ocular dominance columns
columns in the striate cortex, organized based on the fact that each neuron encountered along a perpendicular electrode track responds best to the same eye. -Columns contain neurons that interconnect, but are not sensitive to activity in parallel columns
perception
conscious sensory experience -recognition and action are key for this experience
environmental stimulus
all of the things in our environment that we can potentially perceive
law of pragnanz
also called the law of good figure or the law of simplicity; the central law of Gestalt psychology: Every stimulus pattern is seen in such a way that the resulting structure is as simple as possible. (i.e. the Olympics symbol: We see this display as five circles and not as a larger number of more complicated shapes such as the ones)
bottom up processing
data-based processing; rocessing that is based on incoming data. Incoming data always provide the starting point for perception because without incoming data, there is no perception. -i.e. For Ellen, the incoming data are the patterns of light and dark on her retina created by light reflected from the moth and the tree
neural plasticity
experience-dependent plasticity; the idea that the response properties of neurons can be shaped by perceptual experience. -According to this idea, rearing an animal in an environment that contains only vertical lines should result in the animal's visual system having neurons that respond predominantly to verticals.
global image features
features that can be perceived rapidly and are associated with specific types of scenes (i.e. degree of openness, degree of naturalness, degree of roughness, color, etc) -are holistic and rapidly perceived. They are properties of the scene as a whole and do not depend on time-consuming processes such as perceiving small details, recognizing individual objects, or separating one object from another. -Another property of these features is that they contain information that results in perception of a scene's structure and spatial layout.
selective attention
focusing on specific objects and ignoring others.
Muller-Lyer illusion
illusion of line length that is distorted by inward-turning or outward-turning corners on the ends of the lines, causing lines of equal length to appear to be different -carpentered world theory=European and American city dwellers have a much higher percentage of rectangularity in their environments than non-europeans and so are more susceptible to this illusion.
Mach bands
illusory light and dark bands near a light-dark border.
feature detectors
nerve cells in the brain that respond to specific features of the stimulus, such as shape, angle, or movement (i.e. simple, complex, and end stopped cells)
opponent neurons
neurons in the retina and lateral geniculate nucleus that respond with an excitatory response to light from one part of the spectrum and with an inhibitory response to light from another part. (i.e. B+Y- neuron = the wavelengths that cause an increase in firing are in the blue part of the spectrum, and the wavelengths that cause a decrease are in the yellow part of the spectrum) -provided physiological evidence for opponent process theory to go with the three different cone pigments of trichromatic theory.
lateral geniculate nucleus
nucleus in the thalamus to which neural signals from the retina travel -these neurons have the same center-surround configuration as retinal ganglion cells and thus respond best to small spots of light on the retina. -these neurons regulate neural information as it flows from the retina to the visual cortex -90% of the fibers in the optic nerve arrive at the _____. -is a bilateral structure, which means there is one in the left hemisphere and one in the right hemisphere
photon
packet of energy (contained in light)
selective adaptation
psychophysical procedure by which neurons, if they fire for long enough, they become fatigued, or adapt. -this process causes two physiological effects: (1) the neuron's firing rate decreases, and (2) the neuron fires less when that stimulus is immediately presented again.
binding problem
question of how the visual, auditory, and other areas of the brain influence one another to produce a combined perception of a single object
word superiority effect
the finding that accuracy in recognizing a letter is higher when the letter is in a word than when it appears alone or is in a nonword -If we process the letters in a word in a serial fashion (one letter at a time), it should be more difficult to identify a letter in a word than that letter by itself. -If we process the letters in a word in parallel (all of the letters at once), it should be just as easy to identify a letter in a word as it is to identify that letter by itself. -The nonword condition allowed Reicher to see if there was something unique about processing a letter in a word vs. that letter in a mixed group of letters.
fovea
small, central region of retina containing cones (no rods) and where vision is most acute -when we look directly at an object, its image falls on the _____. -Packed tight with receptors. -Nearly free of ganglion axons and blood vessels. -Each receptor in the _____ attaches to a single bipolar cell and a single ganglion -Each cone in the ____ has a direct line to the brain which allows the registering of the exact location of input.
Simon effect
the finding that reaction times are usually faster and more accurate when the stimulus occurs in the same relative location as the response, even if the stimulus location is irrelevant to the task.
penumbra
the fuzzy border at the edge of the shadow -provides information to the visual system that the dark area is a shadow
Fechner's Law
the observation that the strength of a subjective sensation is proportional to the logarithm of physical stimulus intensity. -Ratio law: the difference in the "feeling" between two physical magnitudes is based on the ratio.
LASIK
surgery that involves sculpting the cornea with a type of laser called an excimer laser, which does not heat tissue. A small flap, less than the thickness of a human hair, is cut into the surface of the cornea. The flap is folded out of the way, the cornea is sculpted by the laser so that it focuses light onto the retina, and the flap is then folded back into place. The result, if the procedure is successful, is good vision without the need for glasses.
disexecutive syndrome
syndrome resulting from frontal lobe damage in which a person is unable to plan or maintain behavior in line with current goals and to suppress responses to goal-irrelevant distractors. -The frontal lobe is known to be the last to develop and the first to deteriorate at older age. One may then explain the increase in distraction in the low-load conditions found for the children and elderly as the result of their reduced frontal cognitive control capacity.
global superiority effect
the finding in various experiments that the properties of the whole object take precedence over the properties of parts of the object -research has shown that incongruent conditions have a greater effect on reaction time in identifying local rather than global features. -Local condition - pay attention to the parts ( The small letters ) -Global condition - pay attention to the whole (The Big letter ) -In the incongruent conditions - The irrelevant part may harm you - hamper, slowdown your response. - In the congruent condition- The irrelevant part may help you - facilitate and speed up a response
accommodation
the process by which the eye changes optical power to maintain a clear image (focus) on an object as its distance varies. -The ciliary muscles at the front of the eye tighten and increase the curvature of the lens so that it gets thicker. This increased curvature bends the light rays passing through the lens to pull the focus point back forward to create a sharp image on the retina. -without this process, Moving an object closer pushes the focus point back behind the retina
attention
the process whereby a person concentrates on some features of the environment to the (relative) exclusion of others -allocation of resources and processing to a region/ object/ dimension...demands resources. -Determines what will get higher semantic processing
ocular dominance
the property of the receptive fields of striate cortex neurons by which they demonstrate a preference to one eye over the other, responding somewhat more rapidly when a stimulus is presented in one eye than when it is presented in the other.
reflectance
the proportion of the light that the object reflects into our eyes -The visual system's problem is that the amount of light reaching the eye from an object depends on this and the total amount of light that is striking the object's surface
response compression
the result when doubling the physical intensity of a stimulus less than doubles the subjective magnitude of the stimulus -As the physical magnitude increases -less sensitive to change - more difficult to create a change in subjective estimation. -Allows to "squeeze" a wide range of magnitudes to a limited "mental ruler" . -(like brightness loudness) similar to Fechner - Large change in physical small change in perception.
response expansion
the result when doubling the physical intensity of a stimulus more than doubles the subjective magnitude of the stimulus
enzyme cascade
the sequence of reactions triggered by the activated visual pigment molecule
retinal size
the smaller it is, the farther away the object is. the larger it is, the closer the object is.
absolute threshold
the smallest amount of stimulus energy necessary to detect a stimulus (statistical threshold)
Just Noticeable Difference
the smallest detectable difference between a starting and secondary level of a particular sensory stimulus. -or DL (=difference level) can be taken as a statistical value that can change between people and within the same person. (psychophysical law of relativity)
difference threshold
the smallest difference between two stimuli that a person can detect.
neuropsychology
the study of the behavioral effects of brain damage in humans.
apparent distance theory
theory that explains that the moon on the horizon (in the moon illusion) appears more distant because it is viewed across the filled space of the terrain, which contains depth information; but when the moon is higher in the sky, it appears less distant because it is viewed through empty space, which contains little depth information. -both the horizon and the elevated moons have the same visual angle, but because the horizon moon is seen against the horizon, which appears farther than the zenith sky, it appears larger.
what pathway
ventral pathway; pathway leading from the striate cortex to the temporal lobe -(1) the pathways are not totally separated, but have connections between them; and (2) signals flow not only "up" the pathway toward the parietal and temporal lobes, but "back" as well. -ventral stream is for perceiving objects
color vision
vision that involves a distributed processing in the cortex, with a number of areas being involved in processing wavelength information and creating color perception
far point
The distance at which the spot of light becomes focused on the retina
near point
The distance at which your lens can no longer adjust to bring close objects into focus
feedback
"backward" flow of information between the what and where pathway -provides information from higher centers that can influence the signals flowing into the system. -This is one of the mechanisms behind top-down processing
sclera
"white part" of the eye
2 ways to signal wavelengths
(1) by trichromatic signals from the receptors, and (2) by opponent signals in later neurons. But why are two different ways necessary? -opponent responding provides a way of specifying wavelengths that may be clearer and more efficient than the ratio of the cone receptor responses. (p. 216)
misapplied size constancy scaling
(p.249) A principle, proposed by Richard Gregory, that when mechanisms that help maintain size constancy in the three-dimensional world are applied to two-dimensional pictures, an illusion of size sometimes results.
saturation
(purity) the relative amount of whiteness in a chromatic color. The less whiteness a color contains, the more saturated it is. -Pink is a desaturated form of red
correspondence problem
An issue faced by the visual system: How to align points in the two retinal images so they can be fused into a single percept.
dark adaptation curve
-a plot of how visual sensitivity changes in the dark, beginning with when the lights are extinguished. - your eyes increase their sensitivity to the dark in two distinct stages: an initial rapid stage and a later, slower stage. these stages are represented on this plot. It increases rapidly for the first 3 to 4 minutes after the light is extinguished and then levels off; it begins increasing again at about 7 to 10 minutes and continues to do so until about 20 or 30 minutes after the light was extinguished -this plot shows that as dark adaptation proceeds, the observer becomes more sensitive to the light.
center surround antagonism
-refers to antagonistic interactions between center and surround regions of the receptive fields of photoreceptor cells in the retina. -enables edge detection and contrast enhancement within the visual cortex. the effect caused by fact that the center and the surround of the receptive field respond in opposite ways
connection between wavelength and color
1. Colors of light are associated with wavelengths in the visible spectrum. 2. The colors of objects are associated with which wavelengths are reflected (for opaque objects) or transmitted (for transparent objects). 3. The colors that occur when we mix colors are also associated with which wavelengths are reflected into the eye. Mixing lights causes more wavelengths to be reflected (each light adds wavelengths to the mixture); mixing paints causes fewer wavelengths to be reflected (each paint subtracts wavelengths from the mixture).
vision
1. light reflected from objects in the environment enters the eye through the pupil 2. it is focused by the cornea and lens to form shape images of the objects on the retina, which contain receptors for vision
layers of LGN
1. magnocellular 2. koniocellular 3. parvocellular
characteristics that determine figures
1. surroundedness 2. relative size 3. contrast 4. convexity (having interior angles measuring less than 180 degrees) 5. symmetry
saliency map
A "map" of a visual display that takes into account characteristics of the display such as color, contrast, and orientation that are associated with capturing attention. This map predicts which areas a person is most likely to attend to.
retinal disparity
A cue to the depth based on the fact that objects within 25 feet project images to slightly different locations on the left and right retinas, so the right and left eyes see slightly different views of the object.
Older eye 3
A decrease in the amount of light entering the eye by a factor of 3 by the age of 60
familiar size
A depth cue based on knowledge of the typical size of objects. -our knowledge of an object's size influences our perception of that object's distance.
size-distance scaling
A hypothesized mechanism that helps maintain size constancy by taking an object's perceived distance into account. According to this mechanism, an object's perceived size, S, is determined by multiplying the size of the retinal image, R, times the object's perceived distance, D. -operates according to the equation S = K (R x D), where S is the object's perceived size, K is a constant, R is the size of the retinal image, and D is the perceived distance of the object. -as a person walks away from you, the size of the person's image on your retina (R) gets smaller, but your perception of the person's distance (D) gets larger. These two changes balance each other, and the net result is that you perceive the person's size (S) as remaining constant.
Steven's power law
A law of magnitude estimation that relates the intensity of the stimulus to the intensity of the sensation; is more accurate than Fechner's law and covers a wider variety of stimuli. -P = KSn. Perceived magnitude, P, equals a constant, K, times the stimulus intensity, S, raised to a power, n.
Emmert's Law
A law stating that the size of an afterimage depends on the distance of the surface against which the afterimage is viewed. The farther away the surface, the larger the afterimage appears. (S=R*D) (size constancy)
subtractive color mixture
A mixture of pigments. If pigments A and B mix, some of the light shining on the surface will be subtracted by A, and some by B. Only the remainder contributes to the perception of color. -when mixed, both paints still absorb the same wavelengths they absorbed when alone, so the only wavelengths reflected are those that are reflected by both paints in common. The blue and yellow blobs subtract all of the wavelengths except some that are associated with green.
object discrimination problem
A problem in which the task is to remember an object based on its shape and choose it when presented with another object after a delay. Associated with research on the what processing stream.
reversible figure-ground
A pattern that's figure and ground can be alternately perceived. i.e. vase/two faces.
dichromat
A person who has a form of color deficiency. can match any color they see with a mixture of no more than two pure spectral lights.
rod monochromat
A person who has a retina in which the only functioning receptors are rods. -Their all-rod retinas provide a way for us to study rod dark adaptation without interference from the cones.
anomalous trichromat
A person who needs to mix a minimum of three wavelengths to match any other wavelength in the spectrum but mixes these wavelengths in different proportions from a trichromat -is not as good as a trichromat at discriminating between wavelengths that are close together.
trichromat
A person with normal color vision. -can match any wavelength in the spectrum by mixing three other wavelengths in various proportions.
late selection
A proposal that selective attention operates at a late stage of processing, so that the unattended inputs receive considerable analysis. -view, in which perception is seen as an automatic process both in the sense that it has unlimited capacity (so that everything is perceived, whether relevant or irrelevant to the current task) and in the sense that it is mandatory (so that people cannot shut down perception of irrelevant information simply because they wish to) -The efficiency of _____ (that is, the extent to which distractors that have been perceived can be prevented from gaining control over behavior) depends on the level of load on cognitive-control functions such as working memory. High working memory load during task performance results in greater distractor interference.
early selection
A proposal that selective attention operates at an early stage of processing, so that the unattended inputs receive little analysis. -view, according to which people have limited perceptual processing capacity and will perceive just what they attend to. Unattended distractors in this view are fully ignored: They are simply never perceived.
method of constant stimuli
A psychophysical method in which a number of stimuli with different intensities are presented repeatedly in a random order.
geon
A simple geometric component hypothesized to be used in the recognition of objects. -non-accidental properties (in most cases your view-point will show you these specific properties),
grating stimulus
A stimulus pattern consisting of alternating bars with different lightness or colors.
module
A structure that is specialized to process information about a particular type of stimulus -neurons that respond to similar stimuli are often grouped together in one area of the brain
Wisconsin Card Sorting Test
A test of executive functions involving rule induction and rule use (from Lecture 10)* -demonstrates the link between prefrontal cortical damage and executive function/working memory/attention/visual processing deficit. -Initially, a number of stimulus cards are presented to the participant. The participant is told to match the cards, but not how to match; however, he or she is told whether a particular match is right or wrong.
exogenous cue
A type of cue that automatically captures attention for a brief period of time. -Bottom-up "from outside" -uncontrolled
endogenous cue
A type of cue used to deliberately direct attention to a specific target or location. The system interprets the symbolic meaning of the cues and its activity is controlled. -Top-down, "from within" -Controlled (generally)
parallel search
A type of visual search in which the target is detected quickly and easily regardless of the number of distractor items in a display. -the target and the distractors are maximally different, differentiated by a single property such as colour, shape, orientation or size.
masking stimulus
A visual pattern that, when presented immediately after a visual stimulus, decreases a person's ability to perceive the stimulus. This stops the persistence of vision and therefore limits the effective duration of the stimulus. (p. 114)
sustained attention
Allocating resources over time, while maintaining a steady level of performance.
parahippocampal place area (PPA)
An area in the temporal lobe that contains neurons that are selectively activated by pictures of indoor and outdoor scenes -what is important for this area is information about spatial layout, because activation occurs both to empty rooms and to rooms that are completely furnished
superior temporal sulcus
An area in the temporal lobe that has been shown to be sensitive to how other people direct their gaze in social situations -for example, it is strongly activated when a passerby makes eye contact with a person, but is more weakly activated if the passerby doesn't make eye contact
angular size contrast theory
An explanation of the moon illusion that states that the perceived size of the moon is determined by the sizes of the objects that surround it. According to this idea, the moon appears small when it is surrounded by large objects, such as the expanse of the sky when the moon is overhead.
moon illusion
An illusion in which the moon appears to be larger when it is on or near the horizon than when it is high in the sky.
rod and frame illusion
An illusion in which the perception of the orientation of a rod is affected by the orientation of a surrounding frame -because the matching and grasping tasks (p.91) involve different processing streams (matching task = ventral, or what, stream; grasping task = dorsal, or how, stream), they may be affected differently by the presence of the surrounding frames. In other words, conditions that created a perceptual visual illusion (matching task) had no effect on the person's ability to take action with regard to the stimulus (grasping task).
Ponzo illusion
An illusion of size in which two objects of equal size that are positioned between two converging lines appear to be different in size. Also called the railroad track illusion.
covert attention
Attention to an object or sound in the absence of overt movements of the relevant receptors (e.g., looking at an object in the periphery of vision without moving one's eyes).
complex cortical cells
Cells in the visual cortex that respond mainly to lines (bars, edges) of specific sizes in specific orientations, but are insensitive to the exact location on which the stimulus falls within their receptive field. -unlike simple cells, which respond to small spots of light or to stationary stimuli, most ____ respond only when a correctly oriented bar of light moves across the entire receptive field. -many respond best to a particular direction of movement
isomerization
Change in shape of the retinal part of the visual pigment molecule that occurs when the molecule absorbs a photon of light. It triggers the enzyme cascade that results in transduction from light energy to electrical energy in the retinal receptors.
simultaneous contrast
Changes in perceived color that occur when a colored stimulus is displayed on backgrounds of various colors --more inhibition=decreased response--->cells fire less---->appear darker (p. 66-67)
extraspectral colors
Colors that do not appear in the spectrum; i.e. brown and purple (Brown is actually a mixture of either red, orange, or yellow with black, and purple is created by mixing red and blue.)
CAPTCHA
Completely Automated Public Turing test to tell Computers and Humans Apart -Used on websites to reduce computerized entry of data -Humans can extract text, computers can't
oculomotor cues
Cues based on our ability to sense the position of our eyes and the tension in our eye muscles. -created by: (1) convergence, the inward movement of the eyes that occurs when we look at nearby objects, and (2) accommodation, the change in the shape of the lens that occurs when we focus on objects at various distances.
binocular cues
Cues that depend on two eyes.
monocular cues
Cues that work with one eye. -include accommodation, pictorial cues, and movement based cues, which are based on depth information created by movement.
spectral sensitivity curve
Curve showing sensitivity at certain wavelengths -We measure the cone ____ by having people look directly at the test light, so that it stimulates only the cones in the fovea, and presenting test flashes of wavelengths across the spectrum. We measure the rod ____ by measuring sensitivity after the eye is dark adapted (so the rods control vision because they are the most sensitive receptors) and presenting test flashes off to the side of the fixation point
orienting of attention
Disengaging attention from one spatial location to another. -OVERT: Move the eyes to foveate the item to be attended; Receive detailed information (fovea) -COVERT: Attend to items in periphery without moving the eyes
lateral eyes
Eyes located on opposite sides of an animal's head, so the visual fields of the two eyes do not overlap or overlap only slightly, as in the pigeon and rabbit. -cannot use disparity to perceive depth, but they gain a wider field of view
liberal criterion
Falls in the left part of the distribution. Under (N): probability of a false alarm is high. Under (S+N): the probability of a hit is high.
neutral criterion
Falls in the middle part of the distribution. Under (N): The false-alarm rate will be fairly low Under (S+N): The hit rate will be fairly high (but not as high as for the liberal criterion).
conservative criterion
Falls in the right part of the distribution. Under (N): The false-alarm rate is low Under (S+N): Hits will be low.
viewpoint invariance
The ability to recognize an object seen from different viewpoints
Landolt C Test
Japanese vision test; it uses a broken ring to test for vision
monochromatic light
light that contains only a single wavelength -used to determine spectral sensitivity
phenomenological method
Method of determining the relationship between stimuli and perception in which the observer describes what he or she perceives
configural superiority effect
Objects presented in certain configurations are easier to recognize than the objects presented in isolation, even if the objects in the configurations are more complex than those in isolation. -Configuration is an "Emergent Feature" (?)
ommatidia
One of the small optical units of the compound eye of arthropods -each has a small lens on the eye's surface that is located directly over a single receptor, so it is possible to illuminate and record from a single receptor without illuminating its neighboring receptors. -researchers used this to demonstrate lateral inhibition (p. 62)
pigment epithelium
Outer layer of the retina on which it rests
executive function (in attention)
Overseeing all other attention systems; the ability to deal with conflicting situations, where there are two rivaling options.
cortical magnification factor
Refers to the degree to which the fovea is overrepresented (takes up a disproportionate amount of space) on the primary visual cortex.
light-from-above heuristic
The assumption that light is coming from above
landmark discrimination problem
The behavioral task used in Ungerleider and Mishkin's experiment in which they provided evidence for the dorsal, or "where,"/"How" visual processing stream. Monkeys were required to respond to a previously indicated location. (lesioning the parietal lobe makes this task hard)
lightness constancy
The constancy of our perception of an object's lightness under different intensities of illumination. -Even if more light is reflected, the perception of the shade of achromatic color (white, gray, and black), which we call lightness, remains the same.
Decision criteria Beta
The degree to which one "ignores" the signal. -larger β = more "no" responses. -larger β = more Misses and Correct Rejections -larger β = Requires a stronger signal for "yes" response.
Sensitivity d'
The degree to which the signal is different than external noise. -Larger d' = increasing the discriminability of signal from noise. -Larger d' = more correct responses (classic).
rat-man demonstration
The demonstration in which presentation of a "ratlike" or "manlike" picture influences an observer's perception of a second picture, which can be interpreted either as a rat or as a man. This demonstration illustrates an effect of top-down processing on perception.
angle of disparity
The difference between the image on one eye and it's corresponding point. On non corresponding points we will see a different value. on corresponding points it will always be 0. -as the stimulus/object gets closer to the observer, the _____ increases -vary with fixation distance. -if the fixation point is farther away, ____ will be smaller. -if the fixation point is closer, _____ will be larger.
change blindness
The difficulty in detecting changes in scenes - The reasons these changes usually remain unnoticed by the observer include obstructions in the visual field, eye movements, a change of location, or a lack of attention.
lightness constancy
The fact that we see whites, grays, and blacks as staying about the same shade under different illuminations -When this effect occurs, our perception of lightness is determined not by the illumination hitting an object, but by the object's reflectance.
oblique effect
The finding that vertical and horizontal orientations can be perceived more easily than other (slanted) orientations.
Hermann grid
The ghostlike gray images at the intersections of the white "corridors". Happens because of lateral inhibition to the receptors at the white crossings. -our perception of these gray images is determined by the response of its bipolar cell. The size of the bipolar cell response depends on how much stimulation it receives from its receptor and on the amount that this response is decreased by the lateral inhibition it receives from its neighboring cells. We determine the amount of inhibition by making the following assumption: The lateral inhibition sent by each receptor's bipolar cell is one-tenth of each receptor's response. (p. 63)
inverse projection problem
The idea that a particular image on the retina could have been caused by an infinite number of different objects. Thus, the retinal image does not unambiguously specify a stimulus. - Another way to state this problem is as follows: If we know an object's shape, distance, and orientation, we can determine the shape of the object's image on the retina. However, a particular image on the retina can be created by an infinite number of objects.
principle of componential recovery
The principle associated with recognition-by-components theory that states that if we can recover (see) an object's geons, we can identify the object.
attended stimulus
The stimulus that a person is attending to at a given point in time.
echolocation
The use of reflected sound waves to determine distances or to locate objects. -Sonar, which stands for sound navigation and ranging, works by sending out pulses of sound and using information contained in the echoes of this sound to determine the location of objects
neural processing
Transformation of electrical signals within a network of neurons, as the signals that originate in the receptors travel through a maze of interconnected pathways between the receptors and the brain and within the brain. - In the nervous system, the original electrical representation of the stimulus that is created by the receptors is transformed by processing into a new representation of the stimulus in the brain.
orientation tuning curve*
a curve that indicate relationship between orientation and firing, and is determined by measuring the responses of a simple cortical cell to bars with different orientations. (p. 77)
WEIRD
Western, Educated, Industrialized, Rich Democratic
selective transmission
When some wavelengths pass through visually transparent objects or substances, such as liquids, plastics, and glass, and others do not. -is associated with the perception of chromatic color. -for example, cranberry juice selectively transmits long-wavelength light and appears red, whereas limeade selectively transmits medium-wavelength light and appears green.
achromatic colors
When light reflection is similar across the full spectrum—that is, contains no hue—as in white, black, and all the grays between these two extremes -colors that contain no hues -white, gray, black
contextual modulation
When the neural response to a stimulus is influenced by the context within which the stimulus occurs. This term has been used to refer to the situation in which a neuron's response is influenced by stimulation of an area outside its receptive field. -Figure 5.43c shows that we can increase the neuron's response to the bar by arranging a few of the lines that are outside the receptive field so that they are lined up with the line that is in the receptive field. When good continuation and similarity cause our receptive-field line to become perceptually grouped with these other lines, the neuron's response increases. This neuron is therefore affected by Gestalt organization even though this organization involves areas outside its receptive field.
border ownership
When two areas share a border, as occurs in figure-ground displays, the border is usually perceived as belonging to the figure.
visual pigments
light-sensitive chemicals that react to light and trigger electrical signals. These signals flow through the network of neurons that make up the retina
attentional blink
a brief period after perceiving a stimulus, during which it is difficult to attend to another stimulus -When presented with a sequence of visual stimuli in rapid succession at the same spatial location on a screen, a participant will often fail to detect a second salient target occurring in succession if it is presented between 150-450 ms after the first one.
White's illusion
a brightness illusion where certain stripes of a black and white grating is partially replaced by a gray rectangle. Both of the gray bars of A and B are the same color and opacity. The brightness of the gray pieces appear to shift toward the brightness of the top and bottom bordering stripes. -lt is clear that area B receives more lateral inhibition, because more of its border is surrounded by white. Because area B receives more lateral inhibition than area A, an explanation based on lateral inhibition would predict that area B should appear darker. But this isn't the case, so lateral inhibition can't explain this illusion.
Balint's syndrome
a condition in which a person lacks the ability focus on individual objects -an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole (simultanagnosia), difficulty in fixating the eyes (oculomotor apraxia), and inability to move the hand to a specific object by using vision (optic ataxia)
detached retina
a condition in which the pigment cannot regenerate. -When part of the retina becomes detached, it has become separated from a layer that it rests on, called the pigment epithelium, which contains enzymes that are necessary for pigment regeneration
optic ataxia
a condition involving lack of coordination between visual inputs and hand movements, resulting in inability to reach and grab objects
presbyopia
a condition where with age, the eye exhibits a progressively diminished ability to focus on near objects; caused by loss of elasticity of the lens
macular degeneration
a condition, most common in older people, that destroys the macula, the center of the cone-rich fovea and a small area that surrounds it. This creates a "blind spot" in central vision, so when a person looks at something, he loses sight of it.
electromagnetic spectrum
a continuum of electromagnetic energy that is produced by electrical charges and is radiated as waves
region of interest approach
a procedure used in brain imaging in which subjects are pretested on the stimuli to be studied. this enables researchers to establish the precise location in the brain that they will be studying for each individual person -One of the challenges of brain imaging research is that although maps have been published indicating the location of different areas of the brain, there is a great deal of variation from person to person in the exact location of a particular area. -For example, in the study we are going to describe, Grill- Spector located the FFA in each observer by presenting pictures of faces and nonfaces and noting the area that was preferentially activated by faces. Locating this ROI before doing the experiment enabled researchers to focus on the exact area of the brain that, for each individual person, was specialized to process information about faces.
visual pigment bleaching
a process by which the retina becomes lighter in color. -When light hits the light-sensitive retinal part of the visual pigment molecule, it is isomerized and triggers the transduction process. It then separates from the opsin part of the molecule. This separation causes the retina to become lighter in color.
visual pigment regeneration
a process in which the retinal and opsin become rejoined. -as some molecules are absorbing light, isomerizing, and splitting apart, molecules that have been split apart are undergoing this process. As retinal combines with opsin in the dark, the pigment regains its darker red color.
dark adaptation
a process that causes the eye to increase its sensitivity in the dark. -i.e. pirates with eye patches; keeping an eye in the dark triggers this process -How to Measure: The first step in measuring it is to light adapt the observer by exposure to light. While the adapt- ing light is on, the observer indicates his or her sensitiv- ity by adjusting the intensity of a test light so it can just barely be seen. This is called the light-adapted sensitivity, because it is measured while the eyes are adapted to the light. Once the light-adapted sensitivity is determined, the adapting light is extinguished, so the observer is in the dark. The course of dark adaptation is usually mea- sured by having the observer turn a knob to adjust the intensity of the test light so it can just barely be seen. Because the observer is becoming more sensitive to the light, he or she must continually decrease the light's in- tensity to keep it just barely visible. The result, shown as the red curve in Figure 3.19, is a dark adaptation curve.
perceptual organization
a process that involves the grouping of elements in an image to create larger objects.
discriminability
a property of geons in which each geon can be discriminated from other geons because each geon has a unique set of NAPs
gestalt psychology
a psychological approach that emphasizes that we often perceive the whole rather than the sum of the parts
method of limits
a psychophysical method for measuring threshold in which the experimenter presents stimuli in alternating ascending and descending order
method of adjustment
a psychophysical method in which the experimenter or the observer adjusts the stimulus intensity in a continuous manner until the observer detects the stimulus
monochromatism
a rare form of color blindness that is usually hereditary -usually have no functioning cones; therefore, their vision has the characteristics of rod vision in both dim and bright lights. -see everything in shades of lightness (white, gray, and black) and can therefore be called color-blind (as opposed to dichromats, who see some chromatic colors and therefore should be called color deficient). -have poor visual acuity and are so sensitive to bright lights that they often must protect their eyes with dark glasses during the day. The rod system is not designed to function in bright light and so becomes overloaded in strong illumination, creating a perception of glare.
ventral simultagnosia
a rare neurological disorder characterized by the inability of an individual to perceive more than a single object at a time
receptive field
a region of space in a sensory neuron in which the presence of a stimulus will alter the firing of that neuron. -if many sensory receptors all form synapses with a single cell further up, they collectively form the ______ of that cell. -For example, the ____ of a ganglion cell in the retina of the eye is composed of input from all of the photoreceptors which synapse with it, and a group of ganglion cells in turn forms the ____ for a cell in the brain.
receptive field
a region of space in which the presence of a stimulus will alter the firing of that neuron -if many sensory receptors all form synapses with a single cell further up, they collectively form the ______ of that cell
conjunction search
a visual search task in which a person is asked to search for a combination of two or more features in the same stimulus -search is serial, so more distractors, longer reaction time -Two factors impact search: 1. Target-distractor similarity 2. Distractor-distractor similarity (homogeneity)
magnitude estimation
a scaling technique to measure above-threshold perceptions -measures the relationship between perceived magnitude and stimulus intensity (p. 16) -The experimenter first presents a "standard" stimulus to the observer (let's say a light of moderate intensity) and assigns it a value of, say, 10; he or she then presents lights of different intensities, and the observer is asked to assign a number to each of these lights that is proportional to the brightness of the standard stimulus. If the light appears twice as bright as the standard, it gets a rating of 20; half as bright, a 5; and so on. Thus, each light intensity has a brightness assigned to it by the observer. There are also ___ procedures in which no "standard" is used. But the basic principle is the same: The observer assigns numbers to stimuli that are proportional to perceived magnitude.
perceptual process
a sequence of processes that work together to determine our experience of and reaction to stimuli in the environment 1. stimulus: what is out there in the environment 2. electricity: electrical signals that are created by the receptors and transmitted to the brain. 3. experience and action: our goal—to perceive, recognize, and react to the stimuli. 4. knowledge: knowledge we bring to the perceptual situation.
autism
a serious developmental disorder in which one of the major symptoms is the withdrawal of contact from other people. People with ____ typically do not make eye contact with others and have difficulty telling what emotions others are experiencing in social situations.
Eriksen's Flanker Test
a set of response inhibition tests used in cognitive psychology to assess the ability to suppress responses that are inappropriate in a particular context. In the tests, a directional response (generally left or right) is made to a central target stimulus. The target is surrounded by non-target stimuli which correspond either to the same directional response as the target (congruent flankers) or to the opposite response (incongruent flankers). It is found that response times are slower for incongruent stimuli than for congruent stimuli. -In the original test described by Eriksen and Eriksen in 1974,[1] letter stimuli were used. Subjects were instructed to make a directional responses to certain letters, for example a right response to the letters H and K, and a left response to S and C. Each stimulus consisted of a set of seven letters, with the target in the central position. Examples of congruent stimuli would be HHHKHHH and CCCSCCC, where both the target and the flankers correspond to the same response. Examples of incongruent flanker stimuli HHHSHHH and CCCHCCC , where the central target letter and the flankers correspond to opposite responses.
occlusion
a signal, or cue, that one object is in front of another. -does not provide information about an object's absolute distance; it only indicates relative distance.
inhibition of return
a slowing of reaction time associated with going back to a previously attended location -a reduced perceptual priority for information in a region that has recently enjoyed a higher priority -an orientation mechanism that briefly enhances the speed and accuracy with which an object is detected after the object is attended, but then impairs detection speed and accuracy
Bayesian inference
a statistical technique that takes probabilities into account to quantify idea of perception as inference -i.e. a mathematical representation of the following: we can ask whether a given object in a kitchen is a loaf of bread or a mailbox. Since it is more likely that a loaf of bread will be in a kitchen, the perceptual system concludes that bread is present
feature search
a visual search task in which a person is asked to search for a single feature
Posner cueing task
a task that assesses an individual's ability to perform an attentional shift. -Two major cue types are used to analyze attention based on the type of visual input. An endogenous cue is presented in the center of the screen, usually at the same location as the center of focus. It is an arrow or other directional cue pointing to the left or right box on the screen. This cue relies on input from the central visual field. An exogenous cue is presented outside of the center of focus, usually highlighting the left or right box presented on the screen. This cue relies on visual input from the peripheral visual field. -invalid cue=unexpected -valid cue=expected -FINDINGS: -shows that visual attention improves perceptual processing in the attended spatial location (with respect to the unattended location) Even without overtly shifting gaze. -Attentional shift to a target area occurs prior to any eye movement -Spatial attention is not completely reliant on conscious visual input
subtraction technique
a technique in which brain activity is measured in two conditions: (1) an initial condition, before the stimulus of interest is presented; and (2) a test condition, in which the stimulus of interest is presented. For example, if we were interested in determining which areas of the brain are activated by manipulating an object with the hand, the initial condition would be when the person is holding the object in his or her hand and the test condition would be when the person is manipulating the object. Subtracting the activity record in the initial condition from the activity in the test condition indicates the brain activation connected with manipulating the object
trichromatic theory of color vision
a theory based on the finding that people with normal color vision need at least three wavelengths to match any wavelength in the test field -the central idea of the theory is that color vision depends on three receptor mechanisms, each with different spectral sensitivities -light of a particular wavelength stimulates the three receptor mechanisms to different degrees, and the pattern of activity in the three mechanisms results in the perception of a color. Each wavelength is therefore represented in the nervous system by its own pattern of activity in the three receptor mechanisms. -Differences in the structure of the long opsin part of the pigments are responsible for the three different absorption spectra - our perception of colors is determined by the pattern of activity in different kinds of receptors (p.207) -They found pigments that responded maximally to: Short wavelengths (419nm) Medium wavelengths (551nm) Long wavelengths (558nm)
signal detection theory
a theory predicting how and when we detect the presence of a faint stimulus ("signal") amid background stimulation ("noise"). Assumes there is no single absolute threshold and detection depends partly on a person's experience, expectations, motivation, and level of fatigue.
cue theory
a theory regarding depth perception that claims that we learn the connection between a cue and depth through our previous experience with the environment.
Facial perception
a type of perception that doesn't require focused attention (as seen in experiment on page 137)
visual search
a type of perceptual task requiring attention that typically involves an active scan of the visual environment for a particular object or feature (the target) among other objects or features (the distractors)
visual object agnosia
a variety of agnosia in which people can reach and grasp objects but cannot identify the objects
scene
a view of a real-world environment that contains (1) background elements and (2) multiple objects that are organized in a meaningful way relative to each other and the background
accidental viewpoint
a view point relative to an object that results in a perception of an accidental (or rarely encountered) property of the object (e.g. a flat quarter produces a straight line)
how pathway
action pathway; some researchers refer to the dorsal pathway as ____ rather than where pathway because it determines how a person carries out an action.
apparent movement
an illusion in which there is actually no movement in the display, just two stationary stimuli flashing on and off. -When two stimuli that are in slightly different positions are flashed one after another with the correct timing, movement is perceived between the two stimuli.
afterimage
an image (usually a negative image) that persists after stimulation has ceased -Opponent cells excited by a particular colour become fatigued after constant firing (responding to stimulus) -When the stimulus (colour) is removed, fatigued cells fall below baseline firing (have a bit of a rest) -The opponent cells that were inhibited by the colour stimulus still fire at baseline level. However because the excited cells are still firing below baseline, the opponent colour is the one we see. -This occurs until fatigued cells recover.
horopter
an imaginary surface that passes through the point of fixation (the object one which the person is focusing and therefore the image that falls on the foveas) and indicates the location of objects that fall on corresponding points on the two retinas. (p.236)
associative agnosia
an impairment in recognition or assigning meaning to a stimulus that is accurately perceived and not associated with a generalized deficit in intelligence, memory, language or attention -people with this can correctly perceive objects presented visually, successfully perform basic tasks like drawing, but cannot assign meaning to visual stimuli. -Can be caused by left occipital and temporal lobe lesion.
spectral sensitivity
an observer's sensitivity to light at each wavelength across the visible spectrum -the rods are more sensitive to short- wavelength light than are the cones
hollow face illusion
an optical illusion in which the perception of a concave mask of a face appears as a normal convex face. -illusion of a protruding convex face, participants directed rapid flicking movements of their hand to the correct position of targets affixed to the surface of the hollow mask. In other words, the visuomotor system can use bottom-up sensory inputs (e.g., vergence) to guide behavior to veridical locations of targets in the real world, even when perceived positions are influenced by top-down processing. -action vs. perception
physiological approach to perception
approach to perception that involves measuring the relationship between stimuli and physiological processes and between physiological processes and perception
primary visual receiving area
area in occipital lobe to which the neural signals travel after the lateral geniculate nucleus
on-center bipolar cells
bipolar cells that have G-protein coupled receptors, and respond to glutamate from the photoreceptors (released when the light is off) by hyperpolarizing. -When there is no glutamate (when the light is on), they depolarize, and generate EPSP to send glutamate to the ganglion cells (this is the direct pathway). -They also receive glutamate from horizontal cells that release glutamate because they are hyperpolarized by surrounding photoreceptors (this is the indirect pathway).
off-center bipolar cells
bipolar cells that have glutamate-gated cation (+ ion) channels that cause a depolarizing (off) response (ESPS, not action potentials) from the influx of Na+
4 basic colors
blue, green, yellow, and red
regularities in the environment
characteristics of the environment that occur frequently
stimulus salience
characteristics of the environment that stand out because of physical properties such as color, brightness, contrast, or orientation
hue
chromatic color; the quality of a color as determined by its dominant wavelength -chromatic colors -the dimension of color that is determined by the wavelength of light; what we know as the color names red, yellow, green, and blue
saturation
chromatic purity: freedom from dilution with white and hence vividness of hue (i.e. pink is a desaturated form of red)
iris
circular muscle that adjusts size of pupil
Cerebral achromatopsia
color blindness due to damage to the cortex -can still have excellent visual acuity and could still see form and movement -This absence of color perception, while other visual functions remained relatively normal, supports the idea that an area specialized for color perception (a color center) must be damaged. But this isn't correct
inferior temporal lobe
lesions here impair learning of discrimination of rewarded objects by shape, color, texture
transduction
conversion of one form of energy into another. In sensation, the transforming of stimulus energies into neural impulses. -the outer segment of the rod is the key part for this process because it is here that the light acts to create electricity. -is triggered when the light-sensitive retinal absorbs one photon of light.
posterior parietal lobe
lesions here impair learning selection of rewarded positions by proximity to landmark
top-down processing
deductive reasoning; approach in which an overview of the system is formulated, specifying but not detailing any first-level subsystems. Each subsystem is then refined in yet greater detail, sometimes in many additional subsystem levels, until the entire specification is reduced to base elements.
deuteranopia
dichromacy characterized by a lowered sensitivity to green light resulting in an inability to distinguish green and purplish-red -perceives blue at short wavelengths, sees yellow at long wavelengths, and has a neutral point at about 498 nm
protanopia
dichromacy characterized by lowered sensitivity to long wavelengths of light resulting in an inability to distinguish red and purplish blue -perceive short wavelength light as blue, and as wavelength is increased, the blue becomes less and less saturated until, at 492 nm, he perceives gray
prosopagnosia
difficulty recognizing the faces of familiar people caused by damage to the temporal lobe -they can easily identify people as soon as they hear them speak
binocular depth cells
disparity-selective cells; Neurons that are tuned to respond to specific amounts of disparity (p. 242) - are responsible for stereopsis
where pathway
dorsal pathway; action pathway; pathway leading from the striate cortex to the parietal lobe -(1) the pathways are not totally separated, but have connections between them; and (2) signals flow not only "up" the pathway toward the parietal and temporal lobes, but "back" as well. -dorsal stream involves a physical interaction with the object
memory color
effect on perception of prior knowledge of the typical colors of objects -Research has shown that because people know the colors of familiar objects, like a red stop sign, or a green tree, they judge these familiar objects as having richer, more saturated colors than unfamiliar objects that reflect the same wavelengths
color-matching experiments
experiment in which observers adjusted the amounts of three different wavelengths of light mixed together in a "comparison field" until the color of this mixture matched the color of a single wavelength in a "test field." (Any three wavelengths can be used, as long as any of them can't be matched by mixing the other two.) The key findings of these color-matching experiments were as follows: 1. By correctly adjusting the proportions of three wavelengths in the comparison field, it was possible to match any wavelength in the test field. 2. People with normal color vision cannot match all wavelengths in the spectrum with only two wavelengths. For example, if they were given only the 420- nm and 640-nm lights to mix, they would be unable to match certain colors. People who are color deficient, and therefore can't perceive all colors in the spectrum, can match the colors of all wavelengths in the spectrum by mixing only two other wavelengths. (p. 207)
saccades
eye movements
frontal eyes
eyes located in front of the head, so the visual fields of the two eyes overlap (humans, monkeys); can use disparity to perceive depth
inattentional blindness
failure to perceive a stimulus that isn't attended, even if it is in full view. (gorilla video) -This typically happens because humans are overloaded with stimuli, and it is impossible to pay attention to all stimuli in one's environment. This is due to the fact that they are unaware of the unattended stimuli.
hyperopia
farsightedness; the inability to see nearby objects clearly -In the eye of someone with farsightedness, the focus point for parallel rays of light is located behind the retina, usually because the eyeball is too short. By accommodating to bring the focus point back to the retina, people with hyperopia are able to see distant objects clearly. -Nearby objects are more difficult for a person with ____ to deal with because a great deal of accommodation is required to return the focus point to the retina. The constant need to accommodate when looking at nearby objects (as in reading or doing close-up work) results in eyestrain and, in older people, headaches.
K cells
ganglion cells that give input to the LGN koniocellular layers (comprise 5% of ganglion cells) -small receptive fields, slow response rate; input from S cones -respond to blue-yellow color
M cells
ganglion cells that give input to the LGN magnocellular layers (comprise 5% of ganglion cells) -large receptive fields, fast response rate, input from rods -respond to movement, subtle contrast
P cells
ganglion cells that give input to the LGN parvocellular layers (comprise 90% of ganglion cells) -small receptive fields, slow response rate, input from L & M cones -respond to red-green color, higher contrast
gist of a scene
general description of the type of scene
cerebral achromatopsia
inability to discriminate among different hues; caused by damage to area V8 of the visual association cortex
bottom-up processing
inductive reasoning; a type of information processing based on incoming data from the environment to form a perception. Information enters the eyes in one direction (input), and is then turned into an image by the brain that can be interpreted and recognized as a perception (output).
top down processing
knowledge-based processing; processing that is based on knowledge -i.e. For Ellen, this knowledge includes what she knows about moths.
law of good continuation
law that states that points that, when connected, result in straight or smoothly curving lines are seen as belonging together, and the lines tend to be seen in such a way as to follow the smoothest path.
law of similarity
law that states that similar things appear to be grouped together
law of common fate
law that states that things that are moving in the same direction appear to be grouped together.
law of proximity
law that states that things that are near each other appear to be grouped together.
law of familiarity
law that states that things that form patterns that are familiar or meaningful are likely to become grouped together
opsin
long strand of retinal protein formed by the action of light on rhodopsin
microwaves
longer wavelengths that penetrate objects rather than reflecting off of them
retinal
molecules contained within visual pigment molecules (p.47) - is crucial for transduction, because it is the part of the visual pigment that is sensitive to light. -made up of 5 types of neurons
interposition
monocular visual cue in which two objects are in the same line of vision and one patially conceals the other, indicating that the first object concealed is further away
persistence of vision
natural phenomenon in which our eyes retain images for a split second longer than they actually appear, making a series of quick flashes appear as one continuous picture
myopia
nearsightedness; an inability to see distant objects clearly -the eye bring parallel rays of light into focus at a point in front of the retina so that the image reaching the retina is blurred. This problem can be caused by either of two factors: (1) refractive ______, in which the cornea and/or the lens bends the light too much, or (2) axial _____, in which the eyeball is too long. Either way, images of faraway objects are not focused sharply, so objects look blurred.
cone
one of the two types of photoreceptors in the retina of the eye which are responsible for color vision as well as eye color sensitivity -respond most strongly to one of three wavelengths of light -we use _____ to see details because they less convergence than rods and therefore better visual acuity (hence a ___-rich fovea)
light adapted sensitivity
one's sensitivity to light indicated by adjusting the intensity of a test light so it can just barely be seen
recognition
our ability to place an object in a category, such as "moth," that gives it meaning
selective reflection
property of reflecting some wavelengths more than others, which is a characteristic of chromatic colors -i.e. Object (tomato-red) reflect only parts of the spectrum, Achromatic objects (no hues), Liquids (selective transmission)
analytic perception
perception of the parts of the shape and, in light of them, perceive the whole shape.
holistic perception
perception of the shape as a single holistic shape before perceiving its parts
rod
photoreceptor cell in the retina of the eye that can function in dimmer light -responsible for color vision as well as eye color sensitivity -registers only shades of grey -_____ vision is more sensitive because it takes less light to generate a response from an individual ___ receptor than from an individual cone receptor. Also, ____ have greater convergence than cones. (p. 58-59) (Many rods summate their responses by feeding into the same ganglion cell, but only one or a few cones send their responses to a single ganglion cell.)
fixations
places where the eye pauses to take in information about specific parts of the scene -people usually fixate their eyes on the object that they are about to attend to, not the object they are currently attending to.
reflectance curves
plots of the percentage of light reflected versus wavelength
principle of uniform connectedness
principle that states a connected region of visual properties, such as lightness, color, texture, or motion, is perceived as a single unit.
principle of common region
principle that states that elements that are within the same region of space appear to be grouped together.
principle of synchrony
principle that states that visual events that occur at the same time are perceived as belonging together.
chromatic adaptation
prolonged exposure to chromatic color - If you close one eye and fixate the other eye on a red surface, adaptation to the red light selectively bleaches your long-wavelength cone pigment, which decreases your sensitivity to red light and causes you to see the reds and oranges viewed with your left (adapted) eye as less saturated and bright than those viewed with the right eye.
non-accidental properties
properties of edges in the retinal image that correspond to the properties of edges in the three-dimensional environment. (i.e. the vast majority of your views of circular objects result in a curved image on the retina, thus the property of curvature is a ____), -properties of a 2D image that in general will not change as your perspective changes
tritanopia
rare form of dichromacy characterized by a lowered sensitivity to blue light resulting in an inability to distinguish blue and yellow -blue at short wavelengths, red at long wavelengths, and a neutral point at 570 nm
heuristics
rules of thumb that provide a best-guess solution to a problem. -The reason for rejecting the term laws is that the rules of perceptual organization and segregation proposed by the Gestalt psychologists don't make strong enough predictions to qualify as laws.
attached shadow
shadow that is on the object itself. it cannot be seen independent of the object -gives information on form
visual acuity
sharpness of vision -normal vision is 20/20 -20/40: You see at 20 ft what others normally see at 40 ft
retina
sheet of tissue at back of eye containing cells that convert light to neural impulses
ultraviolet rays
shorter wavelengths that are usually absorbed by the ozone layer---few reach Earth
metamerism
situation in which two physically different stimuli (contain different wavelengths) are perceptually identical (they look the same) (p. 208)
sonar
sound navigation and ranging - a depth source which works by sending out pulses of sound and using information contained in the echoes of this sound to determine the location of objects
pictorial cues
sources of depth information that can be depicted in a picture
action
stage in the perceptual process that includes motor activities such as moving the head or eyes and locomoting through the environ- ment.
random-dot stereogram
stimulus that contain no pictoral cues affecting the observers depth perception. this is achieved by constructing two identical patterns are generated on a computer, and then shifting a square shaped pattern of the pattern one unit to the right in order to create disparity.
Posner's flashlight
term coined by Posner -Visual attention acts like a mental light beam--improves processing where it is located
contrast sensitivity
the ability to detect differences in light and dark areas in a visual pattern
absorption
the absorbance of light/radiation that passes through a material
visual angle
the angle of an object relative to the observer's eyes -depends both on the size of the stimulus and on its distance from the observer, so when the person moves closer, the visual angle becomes larger. -A small object that is near and a larger object that is far can have the same visual angle.
integrative agnosia
the disability to recognize objects due to the inability to group and integrate the component parts of the object into a coherent whole
wavelength
the distance between the peaks of the electromagnetic waves -describes the energy in the electromagnetic spectrum
visible light
the energy within the electromagnetic spectrum that humans can perceive
reflection
the bouncing back of a ray of light, sound, or heat when the ray hits a surface that it does not go through
refraction
the change in direction of a wave due to a change in its optical medium. -light passing through a glass of water will cause the wave to bend
reflection
the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated. -i.e. when light hits certain surfaces, it will bounce off the surface and hit another surface
semantic regularities
the characteristics associated with the functions carried out in different types of scenes. -For example, food preparation, cooking, and perhaps eating occur in a kitchen; waiting around, buying tickets, checking luggage, and going through security checkpoints happens in airports
Newton's idea of color
the colors that we see in response to different wavelengths are not contained in the rays of light themselves. Instead, these colors are created by our perceptual system.
binocular rivalry
the competition between the two eyes for control of visual perception, which is evident when completely different stimuli are presented to the two eyes
inferotemporal cortex
the cortex of the inferior temporal lobe, in which is located an area of secondary visual cortex that is involved in object recognition -many neurons here that responded best to face
optic nerve
the cranial nerve that serves the retina; conducts signals that flow through the retina to it toward the brain
hue
the degree to which a stimulus can be described as similar to or different from stimuli that are described as red, green, blue, and yellow -one of the main properties of a color -wavelength
ablation
the destruction or removal of tissue in the nervous system.
relative disparity
the difference between two objects' absolute disparities -remains the same no matter where an observer looks
contrast threshold
the difference in intensity at which the bars can just barely be seen.
binocular disparity
the difference in the images in the left and right eyes.
theory of natural selection
the idea that genetically based characteristics that enhance an animal's ability to survive, and therefore reproduce, will be passed on to future generations. Thus, a person whose visual system contains neurons that fire to important things in the environment (such as faces) will be more likely to survive and pass on his or her characteristics than will a person whose visual system does not contain these specialized neurons. Through this evolutionary process, the visual system may have been shaped to contain neurons that respond to faces and other important perceptual information.
selective rearing
the idea that if an animal is reared in an environment that contains only certain types of stimuli, then neurons that respond to these stimuli will become more prevalent. -this effect occurs over a longer timescale and is strongest in young animals, whose visual systems are still developing.
color constancy
the idea that we perceive the colors of objects as being relatively constant even under changing illumination
representation
the image on the receptors of the retina that represent the actual image in the environment
stereopsis
the impression of depth that results from information provided by binocular disparity. (random-dot stereogram)
visual form agnosia
the inability to recognize objects by sight -this disease demonstrates that it is possible to perceive without recognizing; perception and recognition are therefore separate stages
response criterion
the internal rule a person uses to decide whether or not to report a stimulus
convergence
the inward movement of the eyes that occurs when we look at nearby objects
hypercolumns
the larger unit based on the combination of all three types of columns -each one contains a single location column (since it responds to stimuli presented to a particular place on the retina), left and right ocular dominance columns, and a complete set of orientation columns that cover all possible stimulus orientations from 0 to 180 degrees.
emmetropia
the normal refractive condition of the eye in which there is clear focus of light on the retina
partial color constancy
the perception of the object is shifted after adaptation, but not as much as when there was no adaptation. -This means that the eye can adjust its sensitivity to different wavelengths to keep color perception approximately constant as illumination changes.
lightness
the perception of the shade of achromatic color (white, gray, and black)
atmospheric perspective
the perception that objects that appear less sharp and have a slight blue tint are farther away. -The farther away an object is, the more air and particles (dust, water droplets, airborne pollution) we have to look through, making objects that are farther away look less sharp and bluer than close objects.
perspective convergence
the perception that parallel lines in the distance converge as distance increases
perceptual segregation
the perceptual separation of one object from another (as Roger did when he perceived each of the buildings in Figure 5.1 as separate from one another)
neural convergence
the phenomenon of multiple sensory receptors giving information to a smaller number of neural cells
rod-cone break
the place where the rods begin to determine the dark adaptation curve
noncorresponding points
the places on each retina that don't correspond to another point
corresponding retinal points
the places on each retina that would overlap if one retina could be slid on top of the other
blind spot
the point on the retina where the optic nerve leaves the eye and therefore where there are no receptors -it is located off to the side of your visual field, where objects are not sharp in focus, which is why we aren't always aware of our ____. -another reason we dont see the ____ is that some mechanism in the brain "fills in" the place where the image disappears. The brain doesn't fill in the area served by the ____ with "nothing"; rather, it creates a perception that matches the surrounding pattern. (demonstrations on page 52)
Weber's law
the principle that, to be perceived as different, two stimuli must differ by a constant minimum percentage (rather than a constant amount) -The minimal detected addition, is dependent on the base intensity! -The difference threshold is rising as the "base" comparison intensity is rising. -DL/S = K -K is a constant called Weber's fraction -DL is difference threshold -S is standard intensity
binding
the process by which features—such as color, form, motion, and location—are combined to create our perception of a coherent object. -this is why attention is required for enhanced perception
transmission
the process by which the electrical signals in the eye activate other neurons, which in turn activate more neurons. Eventually these signals travel out of the eye and are transmitted to the brain. This step is crucial because if signals don't reach the brain, there is no perception.
absorption
the taking in of light by an object
divided attention
the task of actively paying attention to more than one task at a time
shape constancy
the tendency to perceive the shape of a rigid object as constant despite differences in the viewing angle (and consequent differences in the shape of the pattern projected on the retina of the eye)
reaction time
the time between presentation of the stimulus and the observer's response to the stimulus
transduction
the transformation of one form of energy into another form of energy -i.e. the process by which energy from the environment is transformed into electrical signals in the nervous system
cornea
the transparent front covering of the eye that covers the iris, pupil, and anterior chamber
psychophysics
the use of quantitative methods to measure relationships between stimuli (physics) and perception (psycho).
scotopic vision
the vision of the eye under low light conditions -primarily rods -no color perception
photopic vision
the vision of the eye under well-lit conditions -primarily cones -can perceive color
neutral point
the wavelength at which the protanope perceives gray -At wavelengths above the ____, the protanope perceives yellow, which becomes increasingly saturated as wavelength is increased, until at the long-wavelength end of the spectrum the protanope perceives a saturated yellow.
feature integration theory
theory that claims that the visual system perceives and attends to a stimulus in two distinct stages. 1. The preattentive stage involves rapidly processing features such as color, organization, and location. 2. The focused attention stage involves the use of attention to combine the separate features to perceive a whole object.
perceptual load theory
theory that holds that observers can efficiently filter out task-irrelevant distractors when performing under high levels of perceptual load (e.g., large display size), but fail to do so under low levels of perceptual load -When the task demands a high load of attention (using all of our resources), there is no free attention to waste -BUT - when we have free resources, the excess attention "spills" over to process distractors, or other task that is not in our focus. -tasks involving high perceptual load that engage full capacity will simply leave no capacity for irrelevant distractor perception (leading to an early-selection result). In contrast, in tasks of low perceptual load, spare capacity remaining beyond the task-relevant processing spills over involuntarily to irrelevant distractor processing (leading to late-selection results).
recognition by component theory
theory that proposes that our recognition of objects is based on features called geons, a term that stands for "geometric ions," because just as ions are basic units of molecules, these geons are basic units of objects -also states that we can recognize objects based on a relatively small number of geons
opponent-process theory of color vision
theory that states that color vision is caused by opposing responses generated by blue and yellow and by red and green. -based on Hering's observation that people who are color-blind to red are also color-blind to green, and that people who can't see blue also can't see yellow, led to the conclusion that red and green are paired and that blue and yellow are paired. (based on afterimages after staring at an image for about 30 seconds and then looking away) -Hering proposed three mechanisms, each of which responds in opposite ways to different intensities or wavelengths of light. The Black (-) White (+) mechanism responds positively to white light and negatively to the absence of light. Red (+) Green (-) responds positively to red and negatively to green, and Blue (-) Yellow (+) responds negatively to blue and positively to yellow.
conflicting cues theory
theory that states that our perception of line length depends on two cues: (1) the actual length of the vertical lines, and (2) the overall length of the figure. -these two conflicting cues are integrated to form a compromise perception of length.
theory of unconscious inference
theory that states that some of our perceptions are the result of unconscious assumptions we make about the environment.
synchrony hypothesis
theory that states that when neurons in different parts of the cortex are firing to the same object, the pattern of nerve impulses in these neurons will be synchronized with each other.
illusory conjunction
under some conditions, features associated with one object can become incorrectly associated with another object.
ratio principle
when the illumination is the same over the whole object, then lightness is determined by the ratio of reflectance of the object to the reflectance of surrounding objects. -as long as this ratio remains the same, the perceived lightness will remain the same
