Chapter 3, Cognitive Psychology

cornea

• transparent tissue in front of eye

• role in focusing incoming light

lens

• transparent tissue near front of eye

• role in forming sharp image on retina with cornea, muscles control curvature of lens

retina

• lines back of eye

• light-sensitive tissue

photoreceptors

• cells on retina

• sensitive to light and send signal to adjacent cells when stimulated by light

rods

• photoreceptors

• sensitive to low light levels, unable to discriminate hues & poor acuity

cones

• photoreceptors concentrated in retina’s fovea, less in visual periphery

• discriminate hues & high acuity

• short: detect blue

• medium: detect green

• long: detect red

acuity

• ability to see fine detail

fovea

• centre of retina, eye’s best region of acuity

• looking at object → object lines up to this region

bipolar cells

• neuron in eye

• receive input from photoreceptors → ganglion cells

ganglion cells

• neuron in eye

• receive input from bipolar cells → axons form optic nerve, sends output to lateral geniculate nucleus (LGN)

optic nerve

• bundle of nerve fibres from axons of ganglion cells

• transmits info from eye to brain

lateral geniculate nucleus (LGN)

• within thalamus

• first point for visual info from eye to the brain

single-cell recording

• technique for recording moment-by-moment activation level of individual neuron

lateral inhibition

• pattern in which stimulated cells inhibit activity of adjacent cells

• creates edge enhancement within optic nerve

edge enhancement

• process made by lateral inhibition

• neurons in visual system exaggerate responses to edges of surfaces

receptive field

• portion of visual field that visual system cell responds to

• appropriately shaped stimulus in appropriate position changes cell’s firing rate

centre-surround cells

• neuron in visual system with “donut-shaped” receptive field

• stimulation in centre of receptive field has one effect, simulation in surrounding ring has opposite effect

area v1

• site on occipital lobe where axons from LGN reach cortex

• location where visual info first reaches brain

parallel processing

• brain’s ability to simultaneously analyse & process multiple distinct incoming sensory info

serial processing

• step-by-step, sequential processing of info

• cognitive tasks handled one at a time, previous one must be completed before next begins

ventral pathway

• system of visual circuits/pathways from visual cortex to temporal lobe

• involved in object recognition

dorsal pathway

• system of visual circuits/pathways from visual cortex to parietal lobe

• involved in spatial localization of objects & coordination of movement

binding problem

• problem of reuniting various elements of a scene, given that they are initially processed by different brain systems

neural synchrony

• pattern of neural firing in which one area fires at the same time as another area

• brain uses pattern as indication that both firing are in response to same stimulus

conjunction errors

• perceptual error in which present features are correctly perceived, but not how the features are joined

• e.g., red circle & green square → green circle, red square

Necker cube

• classic reversible/ambiguous figure

• 2D drawing that can be perceived as cube from above or cube from below

reversible/ambiguous figure

• drawings that can be perceived in more than one way

• e.g., vase/profiles, duck/rabbit, Necker cube

figure/ground organization

• processing step in which perceiver determines aspects of stimulus belonging to central object (figure) and which belonging to background (ground)

Gestalt principles

• rules that control how visual input is organized, grouping some elements together, but others independently

visual perception pathway

• light → lens/cornea → retina (fovea) → photoreceptors → bipolar cells → ganglion cells → optic nerve → LGN → area v1 (occipital cortex)

  • → dorsal/where pathway → parietal cortex

  • → ventral/what pathway → inferotemporal cortex

feature integration theory

• proposes that brain processes basic visual features (colour, shape, orientation) in parallel, but needs focused attention to bind features into coherent objects

similarity

• tendency to group objects that share visual characteristics, even if spatially independent

proximity

• tendency to perceived elements close together as related group, and items spaced apart as distinct

continuity

• tendency to perceive continuous patterns/lines instead of disjointed elements, causing eyes to follow visual paths to create coherent whole

closure

• tendency to perceive incomplete shapes/patterns as whole by filling in gaps, creating a unified object instead of fragmented parts

simplicity

• tendency to perceive complex images in the simplest/most stable form to reduce cognitive load

perceptual constancies

• ability to perceive constant properties of objects despite changes in sensory info & viewing circumstances

• size, shape, brightness

visual features

• elements of visual pattern that form overall pattern together

• e.g., lines, curves, diagonals, etc.

unconscious interference

• hypothesized steps followed to use one aspect of visual scene to judge another aspect

perceptual illusions

• systematic errors in perception in which brain misinterprets sensory information, causing conscious experience to differ from reality

distance cues

• visual info enabling brain to perceive depth and spatial relationships

binocular disparity

• distance cues based on differences between 2 eyes’ views

• difference becomes less pronounced farther away

monocular distance cues

• features of visual stimulus indicating distance when viewed with one eye

convergence

• inward turning of eyes when viewing close objects

• greater muscle tension = closer object

lateralized/contralateral processing

• principle in which visual info from one side of visual field is processed by opposite brain hemisphere

• eye on one side of the body acts as a baseline for monitoring the opposite side

• fundamental to how brain processes visual data

• optic chiasm: site where retinal nerve fibres cross over.

pictorial cues

• patterns that can be represented on flat surface to make the sense of a 3D object/scene

interposition

• monocular depth/distance cue

• one object partially blocking another indicates the blocking object is closer and the blocked object is farther away

linear perspective

• monocular depth/distance cue

• parallel lines converge as they become farther away

texture gradient

• monocular depth/distance cue

• perceived density/size/detail of surface textures change as distance increases

motion parallax

• monocular depth/distance cue

• when moving, closer objects move across visual field faster than distant objects

optic flow

• pattern of apparent motion of objects/surfaces/edges in visual field caused by motion between observer and scene

audition

sensory process of perceiving sound (hearing)

vision

ability to see

tactile/touch

ability to perceive through physically contacting something

olfaction

ability to smell

gustation

ability to taste