Perception

Perception

The process of collecting, organizing, and interpreting sensory information from a stimulus for us to experience.

Attention

The process of selecting which incoming information to further process.

Localization

Navigating and grasping objects in a cluttered environment.

Recognition

Determining the identity of objects in the scene.

Abstraction

Extracting critical features of a recognized subject.

Perceptual Constancy

Perceiving objects as unchanged despite variations in sensory input.

Selective Attention

Focusing attention on specific stimuli while ignoring others.

Inattention Blindness

Failure to notice the existence of unexpected items.

Change Blindness

Failure to notice significant changes in the visual environment.

Gestalt Psychology

The perception of figures and forms as whole patterns that are more than the sum of individual sensations.

Depth Cues

Visual cues used to perceive distance and depth.

Monocular Cues

Depth cues that can be perceived with just one eye.

Feature Integration Theory

Information from the visual world is encoded along separate dimensions and then integrated into a coherent perception.

Geons

Geometric forms used to describe the shapes of objects.

Top-down Processing

Perception driven by knowledge, experience, attention, and expectations.

Bottom-up Processing

the mind works from a stimulus and information is processed upward to picture out what the object is

Ambiguous Stimulus

A stimulus that can be perceived in more than one way.

Agnosia

A breakdown or disorder in recognition.

Abstraction

Representing an object with essential information rather than an exact representation.

Perceptual Constancy

Perceiving objects as they are despite variations in physical information.

Color Constancy

Perceiving the true color of an object despite changes in illumination.

Brightness Constancy

Perceiving the lightness of an object despite changes in light intensity.

Shape Constancy

Perceiving the shape of an object as constant despite changes in the retinal image.

Size Constancy

Perceiving the size of an object as constant despite changes in distance.

Illusions

Perceptual experiences that differ from physical reality.

Eye Fixations

Visual scanning takes the form of brief periods during which the eyes are relatively stationary

Saccades

Quick jumps of eye movements

Weapon Focus

victims of armed crimes are often able to very accurately describe what the weapon looked like, but seem to know relatively little about other aspects of the scene

Auditory Attention

attention is multimodal, it can move withing a modality or between modalities, thus attention can also be auditory

Shadowing

we are consciously unaware of, and remember little, if anything, about nonattended information

Figure and Ground

we usually see the figure as a solid stand out and the rest is a less distinct background or ground

Grouping of Objects

we only notice one organization or objects grouped together at a time

Gestalt Psychology Laws of Perception

proximity, similarity, good continuation, closure, and common fate

Proximity

objects near each other tend to be seen as a unit

Similarity

objects similar to each other tend to be seen as part of the same pattern

Good Continuation

objects arranged in either a straight line or a smooth curve tend to be seen as a unit

Closure

even when a figure has a gap, we tend to perceive it as a closed, complete figure

Common fate

when objects move in the same direction, we tend to see them as a unit

Functions of Perception

attention, localization, recognition, abstraction, and perceptual constancy

Relative Size

if an image contains an array of similar objects that differ in size, we interpret the smaller objects as being farther away

Interposition

if one object is position so that is obstructs the view of another, we perceive the overlapping object as nearer

Relative Height

among similar objects those that appear higher are perceived as being farther away

Perspective

when parallel lines in a scene appear to converge in the image, they are perceived as vanishing in the distance

Shading and Shadows

whenever a surface in a scene is blocked from receiving direct light, a shadow is cast

Motion

nearby objects seem to move quickly in the opposite direction while more distant objects move more slowly

Monocular Uses

relative size, interposition, relative height, perspective, shading and shadows, and motion

Stroboscopic Motion

produced most simply by flashing a light in darkness and then, a few milliseconds later, flashing another light near the location of the first light

Real Motion

movement of an object through specific cells in the visual cortex

Selective Adaptation

a loss in sensitivity to motion that occurs when we view motion

Recognition

the perceptual system needs to determine not only where relevant objects are in the scene, but also what they are

Primitive Features

information from the environment that we assemble them properly to be able to recognize

Global-to-local Processing

understanding what the scene is - followed by local processing - using knowledge about the scene to assist in identifying individual objects

Binding Problem

how activity in different parts of the brain, corresponding to different primitives such as color and shape, are combined into a coherent perception of an object

Illusory Conjunction

the error of mixing up features

Stages of FIT

preattentive stage & attentive stage

Preattentive Stage

primitive features such as shape and color are perceived

Attentive Stage

focused attention is used to properly ‘glue’ the features together

Visual Search Task

a standard experimental procedure for distinguishing primitive features from ‘glued-together’ features in which the observer’s task is to determine whether some target object is present in a cluttered display

Dynamic Control Theory

the system rearranges itself for different tasks - as opposed to the being many subsystems for each possible task

Determining What an Object is

the object’s shape plays an important role in determining an object

Feature Detectors in the Cortex

simple cells, complex cells, and hypercomplex cells

Simple Cells

respond when the eye is exposed to a line stimulus

Complex Cells

also respond to a bar or edge in a particular orientation, but it does not require that the stimulus be at a particular place withing its recepetive field

Hypercomplex Cells

require not only that the stimulus be in a particular orientation, but also that it be of a particular length

Temporal Context

the initial perception perseverates, depending on what you see first in an ambiguous stimuli

McGurk Effect

the conflict of auditory and visual information, leading to an illusory result

Inversion Effect

finding that faces but not objects are extremely hard to recognize when they are presented upside-down

Prosopagnosia

a syndrome that can arise following brain injury, in which a person is completely unable to identify faces but retains the ability to recognize objects

Associative Agnosia

a syndrome in which patients with damage to temporal lobe regions of the cortex have difficulty recognizing objects only when they are presented visually

Pure Alexia

loss of the ability to recognize words

Color Metamers

different physical stimuli that lead to the exact same color perception

Available Wavelengths

the perceived color of an object based on the wavelengths of the light that is reflected off the object reaching your eyes

Source Wavelengths

wavelengths provided by the source

Reflective Characteristic

the object itself reflects some wavelengths more than others

Retinal Image Size

the closer object projects onto a large number of photoreceptors, which cover a larger portion of the retina

Emmert’s Experiment

the perceived size of an object increases with both the retinal size of the object and the perceived distance of the object

The Moon Illusion

when the moon is near the horizon, it looks as much as 50 percent larger than when it is high in the sky, even though in fact, the moon’s retinal image is a tiny bit larger when it is directly overhead, because it is a little bit closer when directly overhead than when on the horizon

The Ames Room

a room wherein the observer looks through a peephole, and although the room looks like a normal rectangular room to an observer seeing it though the peephole, it is actually shaped so that its left corner is almost twice as far away as its right corner

Binocular Cues

is limited to objects that are relatively close, requiring the use of both eyes

Binocular Disparity

is used to refer to the difference in the views seen by each eye