AP Psychology: Unit 4 (Sensation & Perception)

ch. 4 of Myers' Psychology for AP, pp. 115-169 + in-class notes

sensation

the process by which sensory receptors & the nervous system receives and represents stimuli

perception

the process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events

bottom-up processing

the analysis that begins with the sensory receptors and works up to the brain's integration of sensory information

top-down processing

the information processing guided by higher-level mental processes, as when we construct perceptions drawing on our experience and expectations

selective attention

focus on particular stimulus; the human mind typically takes in 11 million bits of information per second but only processes about 40

cocktail-party effect

the ability to focus on a single conversation in a noisy environment, while ignoring other stimuli

inattentional blindness

failing to see visible objects when attention is elsewhere; “out of sight, out of mind”

change blindness

failure to notice environmental changes

psychophysics

study of the properties of stimuli and our psychological responses

absolute threshold

minimum stimulation required to detect something 50% of the time; varies with age

signal detection theory

prediction of how & when we detect faint stimuli among background noise; connected to selective attention

subliminal stimulation

stimulation below the absolute threshold

priming

activation, often unconsciously, of associating and creating a predisposition to a response

difference threshold

minimum difference between two stimuli required for detection 50% of the time; explained through Weber’s law

Weber’s law

principle stating difference in stimuli must be proportional rather than by a constant value

sensory adaptation

diminishing sensitivity to constant stimulus; allows focus on important changes

transduction

conversion of one form of energy to another; specifically, the transformation of stimulus energies into neural impulses

wavelength

distance between the peak of one wave to another; determines colour and sound frequency

hue

colour of a wave determined by the wavelength

intensity

the energy in a wave, determines brightness; also called amplitude

pupil

adjustable opening for light in eye

iris

coloured muscle that controls the size of the pupil

lens

the transparent structure behind the pupil that aids in focus

accommodation

lens changing shape in order to account for changing focus

retina

light-sensitive surface in back of eye that has rods and cones to detect light

rods

detects greyscale light (blacks, whites, and greys); handles periphery and twilight conditions

cones

receptor near the centre of the retina that handles daytime vision, fine detail, and colour

optic nerve

carries neural impulses from retina to the occipital lobe for processing

blindspot

point where optic nerve leaves the eye; has no receptors; also called the “optic disk”

fovea

central point of focus in eye

acuity

sharpness of vision

nearsightedness

condition in which near objects are clearer

farsightedness

condition in which far objects are clearer

feature detectors

nerve cells that respond to specific features of the stimulus like shape, angle, and movement

parallel processing

division of the many aspects of vision into subdimensions for simpler processing simultaneously

trichromatic theory

idea that retina contains red, green, and blue receptors that receive the light reflected off of objects

opponent-process theory

idea that opposing retinal processes enable colour vision; red ←→ green, yellow ←→ blue, white ←→ black

audition

sense of hearing; extremely adaptive and sensitive to faint sounds

frequency

how many wavelengths pass through during a time period; determines colour of light and pitch of sound

pitch

the highness or lowness of a tone

middle ear

chamber between the eardrum and cochlea that concentrates sounds with three small bones (hammer, anvil, stirrup) to be transferred into the cochlea through the oval window

cochlea

coiled, fluid-filled tube through which sound waves create neural impulses

inner ear

contains cochlea, semicircular canals, and vestibular sacs

place theory

idea that pitch is linked with where the neural impulses are created in the cochlea

frequency theory

idea that the brain determines pitch based on the frequency of impulses up the nerve

conduction hearing loss

hearing loss caused by mechanical damage to the system that conducts sound into the cochlea

sensorineural hearing loss

hearing loss caused by damage to cochlea’s receptor cells or auditory nerves

cochlear implant

device that converts sound into electrical signals

kinesthesis

system for sensing position and movement of body parts

vestibular sense

sense of body movement, position, and balance; uses gyroscopes in the inner ear

nociceptors

detect harmful temperatures, pressure, or chemicals and translates it into pain

gate-control theory

idea that the spinal cord contains a “gate” that either blocks pain or lets it continue to the brain

sensory interaction

idea that two senses may influence each other

synesthesia

phenomenon where one sensation produces another

gestalt

an organised whole; demonstrates our tendency to integrate pieces of information into a sensible whole

figure-ground organisation

organisation of visual field into objects that stand out from the background

grouping

perceptual tendency to organise stimuli into coherent groups; we organise by proximity, similarity, continuity, connectedness, and closure

depth perception

our ability to see in three dimensions despite our retinas only receiving a two-dimensional image; allows us to judge distance; able to be done from a young age

visual cliff

lab device to test depth perception in infants and young animals

binocular cues

depth cues such as retinal disparity and convergence that depends on the usage of two eyes; used because our retinas receive two different images

retinal disparity

binocular cue for depth perception; computation of distance based on disparity between the images from the two retinas; greater disparity → close object

convergence

binocular cue for depth perception; extent to which the eyes converge inward when looking at an object; more inward → closer object

monocular cues

depth cues such as interposition and linear perspective available to either eye alone

interposition

monocular cue; if one object blocks the view of another, we perceive it as closer

relative motion

monocular cue; objects closer appear to move at a greater speed than faraway objects (i.e. looking out a car window at trees in comparison to the nearby road)

linear perspective

monocular cue; parallel lines appear to meet in the distance; sharper angle → greater distance

phi phenomenon

illusion of movement created by two or more adjacent lights that blink in quick succession

perceptual constancy

seeing the same object (consistent lightness, colour, shape, size) even as illumination and retinal images change

shape constancy

shape remains constant with changing angle of view

size constancy

same size across different distances

lightness constancy

object has constant lightness even in changing illumination

colour constancy

colour remaining constant despite a changing context

perceptual adaptation

adapting to a changed sensory experience; example would be adapting to a displaced or inverted visual field

perceptual set

predispositions to see one thing instead of another; created by top-down processing

extrasensory perception

claim that perception can occur without sensory input

parapsychology

study of paranormal phenomena, including extrasensory perception and psychkinesis