Perception Mega Guide
What is the maximum number of signals produced by a Neuron in one second?
1,000
A patient presents to a neurologist complaining that she has lost vision on the left side. An ophthalmologist has examined her eyes and they are normal. Most likely this patient has...
A post-chiasmal lesion
What is the Power law?
A proportional change of two variables when one is altered
As defined by Fechner, the boundary between a stimulus that can be perceived and one that cannot be perceived is the...
Absolute Threshold
Hyperopia and myopia are problems of...
Accommodation
What is the bending of the lens in order to focus on near and far objects called?
Accommodation
What are the signals that Neurons send and receive?
Action Potentials
Our perception is...
Adaptive
What phenomenon of color vision was trichromatic theory meant to explain?
Additive Color Mixing
Base unit for electric current
Ampere (amp)
What is the distance between the Peak and Trough
Amplitude
Breaking the image of the visual field up into features such as boundaries, colors, shapes, and motion, is the process of visual...
Analysis
In dark adapted low light, how many photons are required to sense light?
As few as 5 photons
What do illusions reveal about vision?
Assumptions our brain makes about reality
Two units of the SI system
Base and Derived
How do we get other units of measurements?
Based on the relationship between the base units
How is light focused onto the Retina?
Bending of the lens behind the Pupil
In signal detection theory, β is a measure of...
Bias
What two factors play roles in a detection experiment?
Bias and Sensitivity
Rods & Cones activate the...
Bipolar Cells
What do rods and cones communicate with?
Bipolar Cells
Patient DB reports that he cannot see anything in his right visual field following a stroke. Nevertheless, he can point to objects in his right visual field, and discriminate the direction of moving objects in this field. His condition is known as...
Blindsight
What is Fourier analysis?
Breakdown of a complex wave into its simple components.
Base unit for luminosity
Candela (cd)
What is the Optic Nerve?
Carries impulses from the Axons of Ganglion Cells to the brain
What is the Soma?
Cell body of a Neuron
What is texture gradients?
Closer objects are seen in more detail than more distant objects
The principle that features that move together are more likely to belong to the same object is called...
Common Fate
What type of photoreceptor cell mediates color vision?
Cones
The percept that the two circles belong to the same object is supported by the Gestalt principle(s) of
Connectedness, Similarity, and Symmetry
A Veteran's Administration neurologist is attempting to characterize loss of sensation in a soldier's leg due to nerve damage sustained in combat. The neurologist administers a number of electric shocks to the leg, at predetermined levels of voltage (always a low amperage) and asks the soldier to indicate whether a shock was detected. The soldier detects half of the shocks presented at 21 volts, and so the neurologist assigns 21 volts as the detection threshold for shock in the leg. The neurologist is using the method of...
Constant Stimuli
An ophthalmologist is testing the acuity of a patient with potential glaucoma. The ophthalmologist shows a series of letter E figures at different angles, the patient's task is to indicate which direction the E is facing. On consecutive trials, the brightness of the letter relative to the background is decreased, so that the letter figure is closer and closer in luminance to the background. The ophthalmologist is testing...
Contrast Acuity
The smallest difference between bright and dark regions of an image that allows them to be seen is a measure of
Contrast Acuity
What happens when an observer correctly reports not detecting a stimuli?
Correct Rejection
The fovea is represented by a majority of the V1 because of what phenomenon?
Cortical Magnification
Which statistic describes sensitivity with no bias?
D-prime
What is an off-center, on-surround receptive field?
Decreased firing rate if center of field is stimulated, Increased firing rate if surrounding area is stimulated.
What make up a Neuron?
Dendrites, Soma, and Axons
What are Binocular cues?
Depth cues that depend on the use of two eyes
What is convergence?
Depth perception based on how much eyes are turned inward
Are monocular cues of depth?
Depth perception that can be done with one eye
A visual psychophysicist is measuring distance perception using a virtual reality headset. In the virtual environment, observers are shown a ball and told that the distance is 10 meters. They are then shown balls at comparison distances, and instructed to label each comparison distance as a ratio of 10 meters (i.e., twice as far, half as far, and so on). The psychophysicist is using...
Direct Magnitude Estimation
A neuroscientist finds a neuron that signals about 200 other neurons. This neuron has...
Divergent Connectivity
What is Disparity?
Each eye is slightly off center but together they allow to see straight (3D vision)
Light is...
Electromagnetic Radiation
What we perceive as visible light is...
Electromagnetic Radiation
The human eye transduces...
Electromagnetic radiation from visible wavelengths.
In a signal detection experiment, if a signal is not presented but the observer reports detecting a signal, that is classified as a(n)...
False Alarm
What happens when an observer incorrectly reports detecting a stimuli?
False Alarm
What is Hyperopia? (When eyeball is too short)
Farsightedness (trouble seeing nearby objects)
What form of object recognition is seen as the better explanation?
Feature analysis
The JND served as the unit of...
Fechner's Scale
Which one represents a higher value of d'?
Figure B
Which one represents greater sensitivity?
Figure B
What are the periods when the eye collects information?
Fixations
Lumens are a measure of...
Flux
What is work?
Force applied over a distance (Joules) Work = Force / Distance
What is a 2AFC task?
Forced Choice between yes and no
Cones are found mainly in the...
Fovea
The center of the retina, where we have the greatest acuity, is the...
Fovea
Bipolar cells activate the...
Ganglion Cells
What are the features called in a Feature analysis?
Geons
Inverse problems...
Have more than one solution
Photopic Vision has...
High Acuity
Scotopic vision has...
High Sensitivity
Why do we have greater sensitivity in our peripheral vision?
High packing density of rods with a converging connections to bipolar cells
What happens when an observer correctly reports detecting a stimuli?
Hit
What are the 3 components to color vision?
Hue, Brightness, and Saturation
A group of cells that together can respond to any angle, from either eye, for a given region of the visual field is a(n)...
Hypercolumn
What is Interposition?
If one object partially blocks our view of another, we perceive it as closer
The amount of light that falls on an object is...
Illuminance
What is an on-center, off-surround receptive field?
Increased firing rate if center of field is stimulated, Decreased firing rate if surrounding area is stimulated
A human factors engineer is trying to figure out why pilots of a certain model of airplane keep missing the warning light that indicates that the fuel mixture is too rich. This causes excessive wear on the engines. The engineer notes that the light is 0.25 degrees of visual angle, and when it comes on, it stays on for 500 ms (1/2 of a second) with a luminance of 5 cd/m2. To increase the probability that a pilot will detect the warning light, the engineer could suggest...
Increasing the size, duration, and luminance of the light.
Cones require how much light to be activated?
Intense light
The smallest difference between two stimuli that can be detected is the...
JND
A psychophysicist is comparing musicians to non-musicians. The psychophysicist presents pairs of pitches with different frequencies, and has observers report whether the two pitches are different or the same. The smallest difference in frequency that is reported as different is recorded. The psychophysicist is measuring...
JND's
Base unit for thermal energy
Kelvin (k)
Base unit for mass
Kilogram (kg)
Where does the Optic Chiasm lead?
LGN (Lateral Geniculate Nucleus) located within the Thalamus
What makes an observer more conservative?
Less false alarms with more misses
What is the average number of signals produced by a Neuron in one second?
Less than 200
What is Presbyopia? (Less flexible lens)
Loss of accommodation
The amount of light reflected off an object is...
Luminance
What methods did S.S. Stevens use to measure intensity perception?
Magnitude Estimation
The two main visual pathways for further visual processing in the cortex are the...
Magnocellular & Parvocellular
From V1, information about motion and location is fed along which pathway?
Magnocellular (M-Cells)
What is an ROC curve?
Measurement of sensitivity and the probability of hits and false alarms
Base unit for length
Meter (m)
What is a JND?
Minimum change in stimulation required to detect a difference.
In a signal detection experiment, if a signal is presented but the observer does not detect it, that is classified as a(n)...
Miss
What happens when an observer incorrectly reports not detecting a stimuli?
Miss
Base unit for substance
Mole (mol)
What makes an observer more Liberal?
More hits with more false alarms
What is Myopia? (When eyeball is too long?
Nearsightedness (trouble seeing far objects)
What are the cells in our brain that support perception?
Neurons
What are the chemicals that signal across Synapses?
Neurotransmitters
Is there such thing as an Absolute Threshold?
No, all thresholds are subjective
Do we see things as they exist in nature?
No, perception adapts with our subjective experience
What are the 5 influences on sensitivity?
Number of Photoreceptors available, Wavelength, Size of stimulated area, Area of retina, and Duration
What is the Frequency of a wave?
Number of waves per second
What is Aerial perspective?
Objects that are very far away appear fainter, bluer, and less distinct
What is the method of adjustment?
Observer controls stimuli intensity until they find the threshold themselves.
What is Magnitude Estimation?
Observers are meant to guess the intensity level of a stimuli in relation to others,
This neuron responds to light from both eyes, but most strongly from light stimulating the left eye, so this neuron has left...
Ocular Dominance
A cell is measured in visual cortex and it is found that the cell increases its firing rate at one point in the visual field, while decreasing its firing rate for areas around that point in the visual field. What kind of receptive field does this Neuron have?
On-Center, Off-Surround
What is a Divergent connection between Neurons?
One Neuron communicates with many Neurons
What is one-to-one connectivity of Neurons?
One Neuron connects to another Neuron directly
What is the pupil?
Opening in the iris where light enters the eyeball
What is the other main theory for color vision?
Opponent-process Theory
Ganglion cell axons form the...
Optic Nerve
What is the reflex that causes us to quickly look at movement caught in our visual field?
Optokinetic reflex (OKR)
What does "Perceiving the present" mean?
Our brain predicts the present due to a couple millisecond delay
What are the two kinds of Ganglion Cells?
P-Cells (Excited by cones) and M-Cells (Excited by rods)
What is Linear perspective?
Parallel lines appear to converge in the distance
From V1, information about object identity is fed along which pathway?
Parvocellular (P-Cells)
What is the highest point of a wave?
Peak
Rods are found mainly in the...
Periphery
The smallest possible amount of light is a...
Photon
What quantum energies make up light?
Photons
In situations of relatively high intensity illumination (i.e., outdoors on a sunny day), we use...
Photopic vision
The cones are mainly involved in...
Photopic vision
What is the method of constant stimuli?
Present stimuli above and below threshold across many trials until observer is able to detect 50% of the time.
The study of the relationship between the physical properties of stimuli and subjective experience of those stimuli is...
Psychophysics
What are these?
ROC Curves
What does a Dendrite do?
Receives signals
For the neuron she has identified as responding to the visual field 20 degrees above the meridian, that location is the neuron's...
Receptive Field
The part of the visual field that causes a change in the firing rate of a neuron is that neuron's...
Receptive Field
The portion of the visual field that causes a neuron to change its firing rate is that neuron's...
Receptive Field
The type of acuity typically measured during a standard eye exam with a chart of letters is...
Recognition Acuity
What is the method of limits?
Reduce and Increase a stimulus between detectable and undetectable, average values to find threshold.
What is the Fovea?
Region of the retina with a high density of cones
What is the Receptive field?
Region on the retina in which stimuli will activate a neuron
Transduction of light is carried out in the...
Retina
A group of visual cells arranged so that nearby cells response to nearby parts of the visual field is called a(n)...
Retinotopy
Information from adjacent points in the visual field is represented by adjacent points on the retina, and this architecture is maintained by LGN and V1. This architecture is known as a...
Retinotopy
Are rods or cones more sensitive to light?
Rods
Scotopic vision is mediated by receptor calls called...
Rods
Light is transduced by...
Rods & Cones
Transduction of light is carried out by...
Rods & Cones
How many types of color-sensitive photoreceptor are there?
S-Cones, meant for short wavelengths and are most sensitive to blue M-Cones, meant for medium length wavelengths and are most sensitive to green L-Cones, meant for long wavelengths and are most sensitive to red
What are the sudden movements of the eye called?
Saccades
The rods are mainly involved in...
Scotopic vision
Base unit for time
Second (s)
What does an Axon do?
Sends signals
In signal detection theory, d' is a measure of...
Sensitivity
The next three questions refer to the following scenario. A neuroscientist is measuring action potentials in neurons in visual are V2 of macaques (a type of monkey). She finds that at 20 degrees of angle above the horizontal meridian (the middle line of the visual field), one of the neurons she is measuring responds to a bar of light. If V2 is organized as a retinotopy like V1 or LGN, how might she find a cell that responds to light 21 degrees above the horizontal meridian (i.e., just above the spot she tested)?
She could test the neurons right next to the one she has identified, as they are most likely to respond to nearby parts of the visual field.
The principle that visual locations that have the same color or shape probably belong to the same object is called...
Similarity
This image might be perceived as a pair of glasses, with an odd black square. The black square seems out of place because of the Gestalt principle(s) of...
Similarity
What is the Optic Chiasm?
Site where the right and left optic nerves cross.
Amanda watches an airplane take off from the airport. As the plane flies away, she perceives its size to remain the same even though the retinal image of the airplane is shrinking because of...
Size Constancy
What is vernier acuity?
Smallest displacement of a line that can be detected
What is dynamic acuity?
Smallest moving target that can be detected
What is recognition acuity?
Smallest size of a familiar object that can be recognized.
What is resolution acuity?
Smallest spacing between components of a figure that can be detected
What is detection acuity?
Smallest stimulus that can be detected
A neurologist tests a patient with complaints of dizziness by having the patient follow a pen with his eyes as the doctor moves the pen back and forth. The patient's eyes jerk from one point to another along the pen's path. This patient is having difficulty with...
Smooth Pursuit
What are the slow movements of the eye to track a moving object?
Smooth pursuit
Is JND subjective or constant?
Subjective
What are the gaps between Neurons?
Synapses
Filmore recently had eye surgery and has to wear a patch over one eye for about a month. During that time, Filmore will still be able to use which of the following depth cues?
Texture Gradient
The greater acuity of foveal vision is due to...
The 1-1 connection between cones and bipolar cells
What is in the center of the Retina?
The Fovea
An audiologist (hearing specialist) measures threshold for sound in a child by gradually increasing the volume of a 440 Hz tone, instructing the child to raise her hand when she hears the tone. The audiologist then tells the child to raise her hand again when the sound goes away, and gradually lowers the volume until the child indicates that she no longer hears it. The audiologist repeats this procedure several times, and averages the intensity values (volumes) at which the child raised her hand to estimate her threshold. The audiologist is using...
The Method of Limits
How does the Iris control the size of the pupil?
The Sphincter tightens and the Dilator relaxes
What is energy?
The ability to do work
What is refraction?
The change in speed light receives when travelling between mediums.
What is Color Constancy?
The color of an object remains the same regardless of the illuminance
The greater sensitivity of peripheral vision is due to...
The convergent connectivity between rods and bipolar cells
What is accommodation (in relation to depth cues)?
The degree of focus required to focus on an object based on distance
What is the Muller-Lyre illusion?
The fins provide subtle depth cues making one seem longer than the other
Cells in V1 are stimulated by what?
The input from both eyes
What is Thermal Energy?
The kinetic energy of molecules (Kelvin)
As we get older, we can expect to experience presbyopia, which means that...
The lens will become less flexible, so the near point gets further away.
What is the retina?
The light-sensitive inner surface of the eye
If an image is stabilized on the retina, the retinal neurons stop responding to the image because neurons respond primarily to change. The reason that our visual world does not disappear when we fixate on an object is that...
The microsaccade eye movement system generates imperceptible saccades that change the retinal image, even when we fixate.
What is Perceptual constancy?
The percept of an object stays constant regardless of our sensations
What is the Critical Flicker Frequency (CFF)?
The point where two separate flashes of light cannot be separated from one.
Psychophysics is the study of...
The relationship between physical properties and subjective experiences.
In signal detection theory, the detection of faint signals is determined by...
The sensitivity and bias of the observer
What is Shape constancy?
The shape of an object remains the same regardless of how we perceive it
The motion of molecules is...
Thermal Energy
Why cant we have both Sensitivity and Acuity throughout our visual field?
They are trade offs, acuity requires high brightness and sensitivity lacks detail.
What is stereopsis?
Three-dimensional visual perception
What is the Period of a wave?
Time to complete one cycle. (Crest to Crest / Trough to Trough)
What is Radiation?
Transfer of energy by electromagnetic waves
What is Convection?
Transfer of energy through liquid or gas
What is Conduction?
Transfer of energy through touch
What theory of color vision does this number provide support for?
Trichromatic Theory
What is the lowest point of a wave?
Trough
What is the Ponzo illusion?
Two converging lines make the line above look as if its farther away due to linear perspective.
What is the eye movement called when they converge to focus on a nearby object?
Vergence system
Rods require how much light to be activated?
Very little
What is the reflex that allows us to focus on a stationary target while we are in motion?
Vestibulo-Ocular reflex
What is Scotopic vision?
Vision that works best in dim light or at night
What is Photopic vision?
Vision that works best in high light levels
The first cortical region to receive visual input in the brain is the...
Visual Area V1 (AKA: Striate Cortex & Primary Visual Cortex)
Where are signals in the LGN sent to?
Visual area V1
What physical property of light is most related to perception of hue?
Wavelength
What is Shading?
We assume the brightest light source is coming from above
What is Template matching?
We recognize objects based on previously encounters
What is Feature analysis?
We recognize objects based on the features and components of that object
What is Biederman Theory?
We recognize objects based on their components
The JND increases with increasing intensity of the standard stimulus according to...
Weber's Law
What is Whytt's reflex?
When bright light is shown to the eye, the Sphincter rapidly tightens
What is relative size?
When objects are equal size, the closer one will take up more of your visual field
What is Weber's Law?
When the intensity of a stimulus increases, the JND will increase too.
What is motion parallax?
When your head moves, objects closer shift faster than objects far away
In Fechner's classic psychophysical theory, the detection of faint signals is determined by...
Whether the signal is above or below an absolute threshold of perception.
In the procedure of direct magnitude estimation, observers are asked to...
compare two stimuli and report a number comparing their relative intensities.
