Exam 1 Study Guide: Perception Part I & II (Vision & Attention)

Key vocabulary terms and concise definitions covering sensation, perception, top-down/bottom-up processing, Gestalt principles, theories of recognition, depth cues, color vision, attention, and related cognitive phenomena from Perception Part I and II.

sensation

is the process of detecting information from the environment through our senses (like eyes, ears, skin) and sending it to the brain.

Ex. When you touch a hot cup, the skin on your hand senses the heat and sends this information to your brain. That feeling of heat is the sensation.

perception

The interpretation of sensory information to form meaningful ideas about objects and events.

bottom-up processing

Processing that starts with sensory input and builds up to higher-level understanding without relying on prior knowledge.

Ex. You see a new fruit you’ve never seen before.
Your eyes notice its color, shape, and texture (raw information).
Your brain uses these details to figure out what kind of fruit it is.

top-down processing

Processing guided by expectations, prior knowledge, and context to interpret sensory information.

Ex. You see a blurry picture of an apple.
Because you know what apples look like, your brain guesses, “That’s an apple,” even if the picture isn’t clear.

Gestalt approach to perception

A view that the whole of perception is more than the sum of its parts; organization into meaningful wholes.

Figure-ground

Perceiving one part of the visual field as the figure and the rest as the background.

Proximity (Gestalt principle)

Elements that are close to each other tend to be grouped together.

Similarity (Gestalt principle)

Items that are alike tend to be grouped together.

Continuity / Good continuation (Gestalt principle)

to group together objects together that form a continuous straight or curved line

Closure (Gestalt principle)

The mind’s tendency to fill in missing parts of a figure to perceive a complete object.

template matching

A bottom-up theory where a current stimulus is compared to stored templates to recognize it.

• templates are exact

• more specific

two pros of template matching

Simple to implement; fast recognition for familiar templates.

problems with template matching

Not robust to large variations; requires many templates to store.

feature analysis

breaking up objects into their parts and recognition of the parts allows us to be able to tell what the object is

prototype matching

Your brain recognizes objects by comparing the object to the “average” version already in your mind.

• you store an average representation not exact match

• more general

prototype vs. template comparison

Templates require exact matches; prototypes generalize to variations by comparing to an average example.

recognition by components (RBC)

Biederman’s theory that objects are recognized by 3D geons and their arrangements.

geons

Geometric primitives proposed in RBC theory used to describe object shapes.

Biederman’s RBC theory

We recognize objects by identifying geons and their spatial relations.

evidence for RBC

Recognition by components accounts for object recognition across viewpoints when geons are identified.

perceptual learning

Perception changes with practice; over time, we can learn to perceive such aspects

Ex. Hearing Chicken sexing for the first time is weird and you do not know what it is but then you learn it is organizing chickens by gender and it isn’t weird anymore → your perception changed

change blindness

Failing to notice large changes in a visual scene when the change coincides with a visual disruption.

perceptual learning

Long-lasting improvement in perception as a result of experience.

word superiority effect

Letters are identified more accurately when they occur within a word than in isolation.

monocular depth cues

Depth cues available with one eye: occlusion, relative size, linear perspective, texture gradient, shading.

occlusion

When one object partially blocks another, the blocked object is perceived as further away.

relative size

Smaller objects are perceived as farther away than larger ones of the same size.

linear perspective

Parallel lines appear to converge with distance, signaling depth.

texture gradient

Texture elements become densely packed with distance, signaling depth.

shading

Variation in lighting to indicate depth and form.

binocular depth cues

Depth cues that require both eyes: retinal disparity and convergence.

retinal disparity

Different images on each retina provide information about depth; greater disparity signals closer objects.

convergence (binocular cue)

The inward turning of the eyes when focusing on a near object, indicating distance.

depth perception

The ability to perceive the distance and three-dimensional relations of objects.

trichromatic theory

Color vision arises from three cone types (sensitive to long/red, medium/green, short/blue wavelengths).

color deficiency

Impaired ability to distinguish certain colors due to cone deficits or malfunctions.

color afterimages

Color aftereffects where the complementary color appears after looking at a color for some time.

opponent-process color pairs

Color channels where colors are paired as opposites (red-green, blue-yellow, black-white) and inhibit each other.

selective attention

Focusing processing on a subset of available stimuli while ignoring others.

dichotic listening task

An experimental task presenting different messages to each ear to study attention.

cocktail party effect

The ability to focus on a single conversation in a noisy environment.

Broadbent’s Early-Selection theory

Attention filters information early, allowing only selected input to be processed for meaning.

Treisman’s Filter Attenuation Theory

Unattended information is not blocked but attenuated, allowing for some processing of non-targets.

Deutsch & Deutsch Late Selection theory

All input is processed to a point, with selection occurring at a late stage before response.

Kahneman’s model of attention and effort

Attention is a limited pool of resources; allocation depends on task demands and arousal.

dispositions and intentions (resource allocation)

Goals and intentions influence how resources are distributed during tasks.

Neisser’s schema theory

Perception is guided by existing schemas; top-down expectations shape perception.

Multiple Resource View

There are separate pools of cognitive resources for different tasks; performance depends on resource sharing.

Brooks (1968) study

Evidence for separate cognitive resources for verbal and motor tasks; dissociation found between modalities.

bottleneck effect

A processing bottleneck where only a limited amount of information can be processed at a time, often at the response stage.

Psychological Refractory Period (PRP) effect

Delay in responding to a second task because the first task is still being processed.

Automaticity

Fast, efficient performance with little conscious control due to practice; can become automatic.

Stroop effect

Interference when the meaning of a color word conflicts with the ink color (e.g., the word RED printed in blue ink).

Schneider & Shiffrin study

Demonstrated differences between consistent vs varied mapping; consistent mapping supports automatic processing; varied mapping requires controlled processing.

consistent mapping

Stimulus-response mappings remain fixed across trials, aiding automaticity.

varied mapping

Stimulus-response mappings change across trials, reducing automaticity and increasing control demands.

Logan’s Instance Theory of Automaticity

Improvement in speed and accuracy comes from retrieving specific practiced instances from memory.

Absolute Identification

A CogLab task where a person identifies which stimulus is present among many possible stimuli; performance changes with the number of categories.

Muller-Lyer Illusion

A visual illusion in which a line’s perceived length is altered by the orientation of arrowheads at its ends.

Blind Spot

Region of the retina where the optic nerve exits; lacks photoreceptors, creating a blind spot in vision.

Brain Asymmetry

Hemispheric differences in function and processing.

Visual Search

Task of locating a target among distractors; feature searches (pop-out) vs. conjunction searches (serial).

Feature search

A search for a target defined by a single, distinct feature that pops out from distractors.

Conjunction search

A search for a target defined by a combination of features requiring attentive, serial processing.

Change Detection

Ability to detect changes in a scene; performance declines with limited attention, leading to change blindness.

Simon Effect

Response compatibility effect where responses are faster when stimulus and response locations correspond.

Simon task

A task used to study the interaction between stimulus location and response selection.

Why is visual perception hard?

it is difficult because of there can be multiple different perceptions… ambiguity

Common Fate

is a principle of perceptual organization suggesting that elements moving in the same direction are perceived as a group.