Psych 450, Exam 1 study guide

Opponent-Process Theory of Color Vision

Based on phenomenological observation data (participant report of perception) Proposed by Hering (1800s) Color vision is caused by opposing responses generated by blue and yellow, and by green and red. Three mechanisms - red/green, blue/yellow, and white/black The pairs respond in an opposing fashion, such as positively to red and negatively to green These responses were believed to be the result of chemical reactions in the retina.

Gestalt features

Brain uses heuristics to group information. Ambiguous information typically perceived with one interpretation. Features bias this interpretation. Gestalt principles describe these rules.

Hyperopia

Farsightedness, a common condition in which light entering the eye is focused behind the retina and accommodation is required in order to see objects clearly.

Resolution acuity

Finest high contrast detail we can visually resolve.

Lobes of the cortex

Frontal, temporal (sides, what), Parietal (Upper rear, where and how), occipital (bottom rear), Insula(buried in lateral fissure), cerebellum.

Behavior of patient D.F.

Damage to ventral pathway due to gas leak. Not able to match orientation of card with slot But was able to match orientation if she was placing card in a slot. Other patients show opposite effects. Evidence shows double dissociation between ventral and dorsal pathways.

the current consensus on the theories of color vision

Discovery of opponent neurons provided physiological evidence for opponent-process theory, to complement the physiological evidence for trichromatic theory. (both theories were correct)

Visual transduction

(conversion of light energy to chemical and ultimately electrical signals for processing) occurs when the retinal absorbs one photon of light.

Efferent nueron

(motor neurons) generate responses in the muscles and glands.

Afferent nerves

(sensory neurons) transduce signals: e.g. vision, hearing, touch.

Considering Weber's work with just noticeable differences, if a person was just able to notice the difference in weight between a 500 gram weight and a weight 10 grams higher, we could reasonably expect the lowest difference this person could detect between a 1000 gram weight and another weight would involve a weight ____ grams heavier.

20

Demetri is a participant in an auditory detection study using the method of constant stimuli. He never detects the 10 unit tone. He detects the 20 unit tone 25% of the trials. He detects the 30 unit tone 50% of the trials. He detects the 40 unit tone 80% of the trials. He detects the 50 unit tone 95% of the trials. His threshold for hearing tones would be taken as the

30 unit tone

An electrode is placed in an orientation column that responds best to orientations of 45 degrees. The adjacent column of cells will probably best respond to orientations of

40 degrees

Color perception is related to the wavelength of light

400 to 450nm appears violet 450 to 490nm appears blue 500 to 575nm appears green 575 to 590nm appears yellow 590 to 620nm appears orange 620 to 700nm appears red

The nanometer range of the visual spectrum

400 to 700 nanometers

Visible light is between _____ and ____ nm within the electromagnetic spectrum.

400; 700

Hyper column

A 1 millimeter block of striate cortex containing two sets of columns, each covering every possible orientation (0-180°) , with one set preferring input from the left eye and one set preferring input from the right eye.

Off bipolar cell

A bipolar cell that responds to a decrease in light captured by the cones.

On bipolar cells

A bipolar cell that response to an increase in light captured by the cones.

Aging-related macular related degeneration(AMD)

A disease associated wiotj aging that affects the macula. AMD gradually destroys sharp central vision, making it difficult to read, drive, and recognize faces there are two form of AMD, wet and dry.

Opsin

A large protein molecule that separates from retinal and must recombine before cell can fire to light again.

Method of adjustment

A method of limits in which the subject controls the change in the stimulus.

Internuerons

A neuron located entirely within the central nervous system. They transmit and process signals: inhibit or facilitate other nerves to fire.

Cones

A photo-receptor specialized for daylight vision, fine visual acuity, and color. Mostly in fovea. Need more light to respond than cones.

Retinitis Pigmentosa

A progressive degeneration of the retina that affects night vision and peripheral vision. RP commonly runs in families and can be caused by defects in a number of different genes that have recently been identified.

Signal Detection Theory

A psycho-physical theory that quantifies the response of an observer to the presentation of a signal in the presence of noise. measures obtained from a series of presentations are sensitivity (d') and criterion of the observer.

Method of constant stimuli

A psychophysical method and which many stimuli, ranging from rarely to almost always perceivable ( or rarely to almost always perceivably different from a reference stimulus), are presented one at a time. Participants respond to each presentation yes/ no, or same/different, and so on.

Magnitude estimation

A psychophysical method in which the participants assigned as values according perceived magnitudes of the stimuli.

Method of limits

A psychophysical method in which the particular dimension of a stimulus, or the difference between two stimuli, it's buried incremental e until the participant responds differently.

Symmetry

A symmetrical region is more likely to be figure.

Column

A vertical arrangement of neurons.

Astigmatism

A visual defect caused by the unequal curving of one or more of the refractive surfaces of the eye usually the cornea.

Pragnanz / good figure / simplicity

Every stimulus is seen as simply as possible (Olympic rings).

Simple feature detector cell

Excitatory and inhibitory areas arranged side by side. Response best to bars of a particular orientation.

Dr. Lanzilotti wants to create a stimulus that will produce an afterimage of a red heart shape against a white background. He should make the heart ______ and the background _______.

green; black

Blue and yellow paints mixed together yield _____; blue and yellow lights mixed together yield ______.

green; white.

Cerebral achromatopsia is when a person

has normal cone functioning, but can not experience color due to a brain injury.

A unilateral dichromat

has trichromatic vision in one eye and dichromatic vision in the other eye.

The edge between a dark shadow and an illuminated checkerboard is a(n)

illumination edge.

Convergence (e.g. the input of multiple rods ultimately impacting a single ganglion cell) results in _________ sensitivity and _______ acuity.

increased; decreased

Relatability

is the degree to which two line segments appear to be a part of the same contour.

Activity in the PPA

is the same for pictures of furnished and empty rooms.

cerebral achromatopsia

loss of ability to see colour due to damage to the brain.

The first step in the procedure for ____________ is to present to the participant a standard stimulus and assign a numerical value to that stimulus.

magnitude estimation

Anomalous trichromat

needs three wavelengths, like in normal vision, but mixes them in different proportions than normal trichromats - impaired ability to discriminate between wavelengths that are close together.

superordinate levels

of specificity (e.g. animal) take longer to process.

Subordinate levels

of specificity (e.g. sparrow, cardinal). Name of object in entry-level category.

A neuron with an excitatory center, inhibitory surround receptive field will respond most when we stimulate

only the center.

The principle of similarity can account for grouping of stimuli that are similar in

orientation, shape, and size.

Color constancy

perception of colors as relatively constant in spite of changing light sources. Affected by light source, adaptation occurs.

Light when traveling can be described in terms of wavelength, or, particularly when absorbed, as consisting of small packets of energy called

photons

the path from the retina to the brain

photoreceptors, bipolar cels, retinal ganglion cells, optic disc, optic nerve, optic chiasm, optic tract, lateral geniculate, optic radiations, occipital cortex.

The EBA is activated by

pictures of body parts.

Reflectance curves

plots of percentage of light reflected for specific wavelengths for surfaces that appear white, gray, and black, and for blue, green, and yellow pigments and a red tomato.

Lorelei s mother is 60 years old. Because of the condition called ______, the closest distance at which she can focus an object is probably about ____ cm.

presbyopia; 100

Dorsal stream

processes where (and how) information. Fast but colorblind. Shows function for both location and for action.

The major dependent variable used in the visual search method is

reaction time

The basic colors in the color circle are

red, green, blue and yellow.

Basic colors of the color circle

red, yellow, green, and blue

The reflectance curve for a white piece of paper would

reflect long, medium and short wavelengths equally.

If you look at a folded index card though a pinhole, you see the border formed by the crease as a(n) ________ because the card looks _______.

reflectance edge; flat

_______ reacts to light to start the process of transduction.

retinal

The ________ can be described as the electronic map of the retina on the cortex.

retinotopic map

The basic function/response of on/off receptive fields,

see slide 16

Rods

senses green and blue, short and medium, A photoreceptor specialized for night vision. Achromatic. More sensitive to light than cones and have greater convergence which results in summation of the inputs of many.

The theory that accounts for response criterion in a detection experiment is

signal detection theory.

Information in shadows

system must determine that edge of a shadow is an illumination edge. If it looks like a tree, it's probably cast by a tree, assuming there is a tree around.

A non-accidental T-junction typically indicates:

that you are seeing more than one object in that area, with one in front of the other.

The difficulty of reading under dim light conditions can be explained by

the fact that rod functioning predominates during dark adaptation, therefore poor acuity.

Penumbra

the fuzzy outline at the edge of a shadow, signals an illumination edge.

The cortical magnification factor occurs in humans because

the small area of the fovea accounts for a large area on the cortex.

Metamers

the stimuli in a metamerism (single wavelength light vs. combination of 3 different wavelengths of light). Look alike because they both elicit the same response pattern in the three cone receptors.

When using the method of constant stimuli, the absolute threshold is determined by calculating

the stimulus intensity detected 50% of the time.

Common fate

things moving in same direction are grouped together.

The process of transforming energy in the environment into electrical energy in the neurons is called

transduction

Unilateral dichromat

trichromatic vision in one eye and dichromatic in other

The ability to readily recognize differently angled views of an object as the same object is an example of:

viewpoint invariance.

Metamerism

when two physically different stimuli are perceived identically

The blind spot, or optic disc, is located

where the optic nerve leaves the eye.

Edge enhancement

white central Kanizsa figure tends to appear brighter than background.

If a kitten is raised in an environment of just horizontal lines, the kitten

would have cortical cells that respond to horizontal lines, but few/none to vertical lines.

Sunlight

Has approximately equal amounts of energy at all visible wavelengths (white light).

standard light-bulb

Has more energy in the long-wavelengths (why it looks slightly yellow).

Benefits of color vision

Helps us classify and identify objects, facilitates perceptual organization of elements into objects, and may provide an evolutionary advantage in foraging for food.

Surroundedness

If one region is entirely surrounded by another, it is likely that the surrounded region is the figure.

Hard problem of consciousness

Involves determining how physiological processes, such as ions blowing across the nerve membrane, cause us to have experiences.

Presbyopia

Literally "old sight". The loss of near vision because of insufficient accommodation.

Chemical cascade

Means that a single reaction leads to increasing numbers of chemical reactions. Enzymes facilitate chemical reactions. This is how isomerizing one pigment leads to the activation of a rod receptor.

Tritanopia

Missing the short wavelength pigment Not linked to X-chromosome Individuals see short wavelengths as blue Neutral point occurs at 570nm Above neutral point, they see red

Additive color mixture

Mixing lights of different wavelengths. Superimposing blue and yellow lights leads to white.

Subtractive colour mixture

Mixing paints with different pigments Additional pigments reflect fewer wavelengths Each component paint still absorbs the same wavelengths as before, so the only wavelengths reflected from the combination are those reflected by BOTH paints.

Myopia

Nearsightedness, a common condition in which light entering the eye is focused in front of the retina and distant objects cannot be seen sharply.

Easy problem of consciousness

Neural correlates of consciousness(NCC)- how physiological responses correlate with experience. Involves looking for connections between physiological responding and experiences such as receiving someone's face or a color.

Orientation columns

Neurons within columns for maximally to the same orientation of similar. Adjacent columns change preference in an orderly fashion. 1 millimeter across the cortex represent entire range of orientation.

Response Bias

Occurs in a study when a participant provides a response that does not reflect their true thoughts, feelings, or behavior. These inaccurate or inadequate responses can negatively impact study results. One type of response bias is the social desirability effect, in which people tend to respond in ways that makes them look good. Participants may be reluctant to admit information that is embarrassing or illegal.

Sparse coding

Only a relatively small number of neurons are necessary. This theory can be viewed as a midpoint between specificity and distributed coding.

ganglion cells

Original cell that receives visual information from photoreceptors via to intermediate neuron types ( bipolar cells and amacrine cells) and transmits information to the brain and midbrain.

Bipolar cells

Original cell that synapses with either rods are cones but not both and with horizontal cells, and then passes the signal on to ganglion cells.

Specificity coding

Pacific neurons responding to specific stimuli. Leads to the grandmother cell hypothesis.

Which of the following is a finding that demonstrates the phenomenon of memory color?

Participants perceive a 620-nm pattern as being redder if that pattern has the shape of a stop sign rather than a mushroom shape.

Distributed coding

Pattern of firing across meaning you're on codes specific objects. Large number of similar can be coded by a few neurons.

How does receptor spacing influence contrast acuity?

Peripheral cones that are less densely packed than foveal cones. Rods are actually physically more tightly packed than cones, but many rods converge to one ganglion cell, eliminating the possibility of acuity gains. thus, peripheral visual acuity lower than verbal acuity.

Good continuation

Points that, when connected, result in straight or smooth curves belong together. Lines are seen as following the smoothest path. Also works with surfaces: Objects partially covered by other objects are seen as continuing behind the covering object.

The Olympic symbol is an example of the Gestalt principle of

Pragnanz/good figure/simplicity.

Global superiority effect

Properties of a whole/larger object take precedence over smaller parts on the object.

Trichromatic Theory of Colour Vision

Proposed by Young and Helmholtz (1800s) Three different receptor mechanisms are responsible for color vision. Based initially on the results of a psychophysical procedure called color matching.

three types of dichromatism

Protanopia, Deuteranopia, Tritanopia

Location columns

Receptive fields at the same location on the retina are within a column.

The perceived colors on the low and high end of the human visual range

Red on the low end, and violet on the high end.

Complex cortical

Responds best to movement of a correctly oriented bar across the receptive field. Many cells respond best to a particular direction of movement.

Parahippocampal Place Area (PPA)

Responds to Scenery, locations.

End - stopped cortical

Response to corners, angles, are bars anything to get earthlink moving in a particular direction.

Extrastriate Body Area (EBA)

Rresponds to bodies, body parts.

3 types of cones

Short (blue), 420nm Medium (green), 534nm Long (red) 564nm Most mammals only have two. colorblind lack at least one type of cone.

Similarity

Similar things are grouped together.

Wavelength sensitivity

Since rods aree insensitive to higher wavelengths(red), we can use red leghtr for additional ilumination at night without affecting our night vision (we stay dark adapted).

Ungerleider and Mishkin experiment

Slide 8. Object discrimination problem. Monkey is shown an object then presented with two choice task. Goal is to select the object representative of the shape the monkey was shown at the start of the trial. Reward given for detecting the target object. Landmark discrimination problem- Monkey is trained to pick the food well next to a cylinder Two food wells, one with food, one empty. The one closest to an object is always the one with the food reward.

When looking at a scene, the different sections of the scene are processed by many different location columns. Through the use of all of the location columns, the entire scene can be perceived. This effect is referred to as

Specificity coding

Sensation

The ability to detect the pressure of a finger and, perhaps, to turn that detection into a private experience.

Cortical magnification

The amount of cortical area( usually specified in millimeters) devoted to a specific region (1 degree) in the visual field. The cortical representation of the phobia is greatly magnified compared to the cortical representation of peripheral vision. Fovea: .01% of retinal area, 8-10% of cortical maps area.

Macula

The central part of the retina that has a high concentration of cones.

Weber's fraction

The constant of proportionality in Weber's law. If an individual was just able to tell difference between 40 and 41 gram object, they would also be just able to discriminate 400 from 410 gram. Wt=1:40, Length=1:100

Near point

The distance at which the natural lens can no longer a test for a closer object.

Farpoint

The distance when light becomes focused.

Memory color

The effect on perception of prior knowledge of the typical colors of objects. The colors of very familiar objects (e.g. stop signs) are judged as richer and more saturated than are the colors of unfamiliar objects reflecting the same wavelengths.

Entry-level category

The label that comes most quickly to mind when naming an object (i.e. "Bird" or "Dog").

absolute threshold

The minimum amount of stimulation necessary for a person to detect a stimulus 50% of the time.

End stopping

The process by which a cell in the cortex first increases its firing rate as the bar length increases to fill up its receptive field, and then decreases its firing rate as the bar is lengthened further

Accommodation

The process by which the eye changes its focus ( in which the lenses gets fatter as gaze is directed toward nearer objects).

Size

The smaller region is more likely to be figure. Car is smaller than road. Plane is smaller than sky.

Just notable difference (JND)

The smallest detectable difference between two stimuli, or the minimum change in a stimulus that enables it to be correctly judged as different from a reference stimulus.

Saturation

The strength of the hue. Adding white to a color results in less saturated color.

Protanopia

They are missing the long-wavelength pigment See short-wavelengths as blue As wavelength increases, blue becomes less saturated until hitting neutral point Neutral point occurs at 492nm - perceived as gray Above neutral point, they see yellow, which becomes less intense at longer wavelengths

Deuteranopia

They are missing the medium wavelength pigment Perceptually very similar to protanopia Individuals see short-wavelengths as blue Neutral point occurs at 498nm Above neutral point, they see yellow

Proximity/Nearness

Things that are near to each other are grouped together.

Perception

Thought of as the act of giving meaning to those detected sensations.

Reflect

To redirect to something that strikes a surface - especially light, sound, or heat - usually back toward its point of origin.

Problems with specificity coding

Too many different simulation to assign specific neurons. Most neurons respond to a number of different stimuli.

viewpoint invariance

We can tell that the three chair images in the top left image are all different angles of the same chair.

non accidental features

We use visual cues (i.e. T-junction, Y-junction and Arrow junction) to indicate that an object is blocking the view of another object.

Refraction

When light travels from a slow medium to a faster medium or from a fast medium to a slower medium rays that are not perpendicular to the surface will bend. The amount of bending is based on the speed difference.

Optic chiasm

Where inner visual fields cross to other hemisphere.

Retinal

a light sensitive molecule that changes its shape, called isomerization.

Response criterion

a persons individual response bias.

After training participants on the recognition of Greeble stimuli, Gauthier et al. found that the neuron in the FFA responded

about as well to Greebles as to human faces.

Y and arrow junctions

almost always indicate object corners (no occlusion)

T-junctions

almost always occur when one object is occluding another.

Prosopagnosia

an inability to recognize familiar faces.

The flow of information in the LGN is best described as:

bi-directional, with signals coming from the retina and the cortex to the LGN.

Rods and cones synapse with ______ cells, which then synapse with ____ cells.

bipolar; ganglion

A participant is viewing a black and white (full contrast) grating stimulus with a cycle subtending two arcminutes of visual angle. If the photoreceptors in line with this grating have receptive fields of slightly under 1 arcminute (e.g., the centers of the receptors are just under 1 arcminute apart), the stimulus will likely be perceived as ________. If the photoreceptors have receptive fields of 1.5 arcminutes, the stimulus will likely be perceived as ________. (Note: the period of a visual waveform is also known as its cycle).

black and white bars: a solid gray patch

Nora adapts to a yellow stimulus for about 60 seconds. If she looks at a white surface and blinks, the afterimage she sees will appear to be

blue.

If you cover the penumbra with a black marker, the perception of the border

changes from an illumination edge to a reflectance edge.

To double the perceived brightness of a light, you need to multiply the physical intensity of the light by about 9. This is an example of response

compression

Uniform connectedness

connected region of visual properties are perceived as single unit.

The difference between the method of limits and the method of adjustment is that, in the method of adjustment, stimulus intensity is changed in a _______ manner.

continuous

Illusory contours

contours that appear real but have no real physical edge

The structure of the eye that provides about 80% of the eye s focusing power is the

cornea

When visual pigments become bleached they are

detached from the opsin.

In Ungerleider and Mishkin s (1982) research, monkeys who had had their temporal lobes removed had difficulty

discriminating between objects.

A researcher finds that damage to Area A of the brain results in the loss of Function A but not Function B. In another individual, damage to Area B results in the loss of Function B but not Function A. These results are best described as a/an

double dissociation.

Which of the following is NOT a type of column in the striate cortex?

double dissociative

Finding the neural correlates of consciousness is related to the

easy problem of consciousness.

Illumination edges

edges where lighting of two surfaces changes (diff. lighting, shadow)

Reflectance edges

edges where the amount of light reflected changes between two surfaces (different material)

Common region

elements in the same region tend to be grouped together.

When shown a picture of a sparrow, Kathy most quickly comes up with the term "bird", slightly later coming up with the term "sparrow". For Kathy, the term "bird" here serves as a/an:

entry-level category.

Response __________ occurs in a magnitude estimation experiment when doubling the stimulus intensity MORE than doubles the subjective magnitude of the stimulus.

expansion

pigment bleaching

After absorbing a photon the rhodopsin molecule begins to break down into retinal and ospin.

Grating stimuli

Alternating light and dark bars that are used to measure contrast acuity.

Cataract

An opacity of the crystalline lens.

How is light conceptualized?

As a wave when it travels and a particle stream of photons when absorbed.

Response expansion

As intensity increases, the perceived magnitude increases more quickly than the intensity.

Response compression

As intensity increases, the perceived magnitude increases more slowly than the intensity.