Sensation and Perception Exam 2: Vision, Color, Depth, Motion & Eye Movements Study Guide

What is the primary function of the dorsal stream in visual processing?

Action-decision and making.

What does the ventral stream allow us to do?

Identify an object or being.

What is the role of the inferotemporal cortex (IT) in monkeys?

It is involved in object recognition.

What visual area is responsible for color management?

V4.

What is the primary visual cortex (V1) responsible for?

The first processing of visual information in the occipital lobe.

What is the significance of 'grandmother cells' in neuroscience?

They are hypothetical neurons that respond to specific entities regardless of appearance.

Define illusory contours.

Perceived edges or contours that do not have a physical change in the image.

What does the Gestalt principle of Good Continuation state?

Two elements will group together when they lie on the same contour.

What is the effect of surroundedness on figure-ground assignment?

The surrounding region is likely to be perceived as ground.

What are non-accidental features in object recognition?

Features that do not depend on the exact viewpoint of the observer.

What is the Pandemonium model in object recognition?

A model claiming that objects are recognized by pooling features noticed by 'feature demons'.

What are Biederman's geons?

Simple 3D shapes that serve as the basic building blocks for identifying objects.

What is the role of the lateral occipital complex (LOC) in humans?

It helps manage motion detection and body shape detection.

What is the importance of position invariance in visual neurons?

It allows a cell to respond to stimuli regardless of their position in the visual field.

What does the term 'accidental viewpoint' refer to?

A viewing position that produces regularity in the image not present in the world.

What is the main challenge in object recognition?

Recognizing objects regardless of changes in their appearance.

What is the definition of color in the context of perception?

A psychophysical phenomenon that depends on relationships between various physical features.

What are the three steps to color perception?

Light detection, wavelength/spectrum discrimination, and appearance.

What is the electromagnetic spectrum range visible to humans?

400-700 nm.

What is an illuminant in color perception?

The light source that illuminates an object.

What does the term 'spectral' refer to?

It refers to the wavelength of light.

What is the function of V2 in visual processing?

Depth perception, object texture, and shapes.

How does the visual processing hierarchy function?

It breaks down a scene into various features and compiles them at different visual areas.

What is the main focus of mid-level vision?

Finding edges and grouping basic features into contours, surfaces, and shapes.

What is the significance of symmetry in figure-ground assignment?

A symmetrical region is more likely perceived as a figure.

What does the principle of common fate state?

Elements moving in the same direction at the same speed are grouped together.

What portion of the electromagnetic spectrum can humans see?

400-700 nm

What does 'spectral' refer to?

It refers to the wavelength of light.

What is an illuminant?

The light source.

Define power spectrum.

Description of the amount of energy/power at each wavelength.

What is the Principle of Univariance?

The response of any single photoreceptor is consistent with an infinite amount of different wavelength-intensity combinations.

What happens to color vision under scotopic conditions?

Only rods are active, leading to colorblindness in dim light.

What is the Trichromatic Solution?

Any perceivable color can be reproduced using only 3 colors of light to stimulate each of the 3 cone types.

What are color metamers?

Two different colors that appear the same under one light but differently under another.

Who discovered that white light can be broken into distinct colors?

Isaac Newton.

What did Helmholtz and Young contribute to color perception?

They independently discovered the trichromatic nature of color perception.

What is additive color mixing?

A mixture of lights with different spectra.

Define color space.

A 3-dimensional space that describes all colors, separating into intensity and chromatic components.

What is the Opponent Color Theory?

Claims that perception of light is based on the output of 3 channels, each based on opponency between 2 colors.

What are opponent channels?

L - M (red-green), S - (L+M) (blue-yellow), L+M (white-black).

What causes negative color afterimages?

Neural adaptation of color-opponent cells.

What is a unique hue?

Any of four colors that can only be described with a single color term: red, yellow, green, blue.

What is color constancy?

The tendency of a surface to appear the same color under a wide range of illuminants.

What is color blindness?

The result of missing or anomalous M or L cones leading to anomalous color vision.

What is anomalous trichromancy?

One cone has abnormal pigment with absorption shifted closer to one another.

What is dichromancy?

Missing one type of cone pigment: Protanopia (L cone), Deuteranopia (M cone), Tritanopia (S cone).

What is monochromancy?

Only one pigment/cone type (usually S cone) or missing all cones.

What is depth perception?

The ability to figure out how far away an object is in the world.

What is binocular summation?

Improved vision via probability summation from both eyes.

What is stereopsis?

Depth perception that results from binocular disparity.

What is the moon illusion?

The perceived size of the moon appears larger when it is near the horizon compared to when it is overhead.

What is vergence angle?

The angle between the eyes that can be used to deduce depth at the point of focus.

What are monocular cues?

Depth cues that can be perceived with one eye, providing multiple depth cues in most environments.

What is occlusion in depth perception?

When one object obstructs the view of another object, indicating which is closer.

What is the difference between non-metrical and metrical depth cues?

Non-metrical cues provide order information only, while metrical cues provide quantifiable measures of depth.

What does relative size cue indicate?

Objects of the same size appear smaller when they are further away.

What is aerial perspective?

The effect of atmospheric haze making distant objects appear blurrier and bluer.

What is linear perspective?

The visual phenomenon where parallel lines appear to converge at a vanishing point in the distance.

What is motion parallax?

A depth cue where nearby objects move quicker than distant objects as the observer moves.

What is optic flow?

The changing angular position of points in a perspective image as we move through the world.

What is accommodation in depth perception?

The process of the lens contracting or flattening to focus on objects at different distances.

What is binocular disparity?

The difference in images projected to each eye, which helps in depth perception.

What is the horopter?

The location of objects whose images lie on corresponding points in the two retinas.

What is Panum's fusional area?

The region in front of and behind the horopter where binocular single vision is possible.

What is a stereoscope?

A device that presents one image to one eye and another image to the other eye to create depth perception.

What is a random dot stereogram?

A stereogram made of randomly placed dots, where stimuli visible stereoscopically are cyclopean stimuli.

What is binocular rivalry?

The phenomenon where different images are shown to each eye, often resulting in the suppression of one image.

What is the motion aftereffect (MAE)?

The illusion of motion of a stationary object after prolonged exposure to a moving object.

What is apparent motion?

A motion percept that results from the rapid display of stationary images in different directions.

What is strabismus?

Misalignment of the two eyes, leading to depth perception issues.

What is esotropia?

A condition where one eye deviates inwards.

What is exotropia?

A condition where one eye deviates outwards.

What role does the brain play in combining information from both eyes?

The brain integrates the different images from each eye to create a single percept of depth.

What is the significance of disparity-tuned neurons in V1?

These neurons respond to the disparity between images from the two eyes, contributing to depth perception.

What is the relationship between motion perception and object position tracking?

Motion perception is crucial for tracking the position of objects as they move through space.

What is the role of accommodation blur in depth perception?

Blur from focusing on objects at different depths provides cues about their relative distance.

What is the effect of adding a shadow to an object?

It gives the object depth, enhancing the perception of three-dimensionality.

What is the Reichardt Detector used for?

It is a model for building motion-sensitive cells that respond to motion in a particular direction and at a specific velocity.

What is the correspondence problem in motion perception?

It is the challenge of determining the correspondence between features in successive frames over time.

What does the aperture problem refer to?

It refers to the ambiguity in determining the direction of motion when viewed through a small aperture.

What was the main finding of the Moving Rhombus experiment (2002)?

Perception of travel is influenced by occluders, contrast, and edge angles.

What is first-order motion?

Motion defined by changes in luminance.

What is second-order motion?

Motion defined by changes in contrast or texture, not by luminance.

What role does Area MT/V5 play in motion perception?

It encodes global pattern motion.

What is the function of the lateral intraparietal area (LIP)?

It is involved in the control of eye movements.

What are fixational eye movements?

Involuntary eye movements that occur when trying to maintain fixation on an object.

What are microsaccades?

Fast, jerky eye movements that help prevent Troxler fading.

What is the vestibulo-ocular reflex (VOR)?

A reflex that maintains vergence and line of sight during head movements.

What is vergence in eye movements?

Eye movements that keep both eyes pointing at the same object, converging for closer objects and diverging for farther ones.

What are saccades?

Jerky eye movements that rapidly change fixation from one object to another.

What is saccadic suppression?

The reduction of visual sensitivity during saccadic eye movements to eliminate motion smear.

What is dynamic remapping in the context of eye movements?

The remapping of receptive fields in anticipation of a saccade before it is executed.

What is the significance of the Newsome/Pare (1988) study on monkeys?

It demonstrated that lesions in the MT area significantly impaired motion perception in monkeys.

What is the role of the frontal eye fields (FEF)?

It is involved in the voluntary control of eye movements.

What is the purpose of optokinetic nystagmus (OKN)?

It is triggered by tracking a moving field and helps stabilize vision.

How do Reichardt-style motion detectors function?

They respond to motion by comparing signals from two adjacent receptors with a slight delay.

What is a luminance-defined object?

An object that is delineated by differences in reflected light.

What is a texture-defined object?

An object that is defined by changes in contrast or texture, not by luminance.

What are the three pairs of muscles that control eye movements?

Superior/Inferior Rectus, Lateral/Medial Rectus, and Superior/Inferior Oblique.

What is the function of the superior and inferior rectus muscles?

They control the vertical orientation of the eye.