AP Psychology Sensation and Perception

Sensation

The process by which our sensory receptors and nervous system detect external or internal stimuli (like light

Transduction

The conversion of physical or chemical stimuli (light

Absolute threshold

The minimum level of a stimulus needed to detect it 50% of the time

Just-noticeable difference (JND)

The smallest detectable difference between two stimuli

Sensory adaptation

Diminished sensitivity to a constant stimulus over time

Weber's law

Principle stating that the detectable difference between stimuli is a constant proportion of the original stimulus

Sensory interaction

When one sense influences another

Synesthesia

A condition in which stimulation of one sense triggers an automatic

Retina

Light-sensitive inner surface at the back of the eye containing rods and cones; converts light into neural signals

Blind spot

Area on the retina where the optic nerve exits the eye; no photoreceptors are present

Optic nerve

The nerve that carries visual information from the retina to the brain

Lens

Transparent structure behind the pupil that changes shape to focus light onto the retina; thicker for near objects

Accommodation

Process by which the lens changes shape to focus near or far objects onto the retina for clear vision

Nearsightedness (Myopia)

Condition where close objects are seen clearly but distant objects are blurry due to an elongated eyeball or excessive lens curvature

Farsightedness (Hyperopia)

Condition where distant objects are seen clearly but near objects are blurry due to a shortened eyeball or insufficient lens curvature

Photoreceptors

Specialized cells in the retina (rods and cones) that respond to light and convert it into neural signals

Rods

Retinal receptors sensitive to low light levels and peripheral vision; detect black

Cones (blue

green

Trichromatic theory

Theory that the retina contains three types of cones sensitive to red

Opponent-process theory

Theory that colors are processed in opposing pairs (red/green

Afterimages

Visual impressions that remain after a stimulus is removed

Ganglion cells

Neurons in the retina that receive input from bipolar cells and transmit signals to the optic nerve for visual processing

Dichromatism

Type of colorblindness where one of the three cone types is missing or nonfunctional

Monochromatism

Rare type of colorblindness in which only one cone type functions

Prosopagnosia

Disorder that prevents recognition of faces

Blindsight

Condition where a person can respond to visual stimuli without consciously perceiving them

Wavelength

Distance between successive peaks of a wave; determines color in vision and pitch in hearing

Pitch

Tone's perceived highness or lowness

Amplitude

Height of a wave; in sound

Loudness

Perception of a sound's intensity

Pitch perception

How we interpret frequency as high or low sounds; theories include place

Place theory

Theory that links pitch perception to the specific location on the cochlea's basilar membrane that is stimulated

Volley theory

Theory that groups of auditory neurons fire in rapid succession to produce a combined frequency matching the sound wave

Frequency theory

Theory that the rate of nerve impulses traveling up the auditory nerve matches the frequency of a tone

Sound localization

Ability to determine the origin of a sound based on differences in timing and intensity at each ear

Conduction deafness

Hearing loss caused by damage to the mechanical system (eardrum or ossicles) that conducts sound to the cochlea

Sensorineural deafness

Hearing loss caused by damage to the cochlea’s receptor cells or auditory nerve

Olfactory system

The sensory system for smell

Thalamus

Brain structure that acts as a sensory relay station for most senses (except smell)

Pheromones

Chemical signals released by animals (including humans) that influence behavior or physiology of others

Gustation

The sense of taste; involves detecting sweet

Taste receptors

Cells located in taste buds on the tongue that detect specific flavors

Supertasters

Individuals with heightened sensitivity to certain tastes

Medium tasters

Individuals with moderate sensitivity to taste stimuli; average number of taste buds

Nontasters

Individuals with low sensitivity to taste stimuli; fewer taste buds

Warm/cold receptors

Sensory receptors in the skin that detect changes in temperature

Gate control theory

Theory proposing that the spinal cord contains a “gate” that can block or allow pain signals to travel to the brain; explains why rubbing a sore area reduces pain

Phantom limb

Sensation that an amputated or missing limb is still attached and moving

Vestibular sense

Sense of body movement

Semicircular canals

Three fluid-filled structures in the inner ear that help maintain balance by detecting rotational movements of the head

Kinesthesis

Sense of the position and movement of individual body parts

Bottom-up processing

Sensory analysis that begins with the incoming stimuli and works up to the brain's interpretation

Top-down processing

Information processing guided by higher-level mental processes

Schema

Mental framework that organizes and interprets information

Perceptual set

A mental predisposition to perceive one thing and not another; influenced by expectations or context

Gestalt psychology

School of thought emphasizing our tendency to integrate pieces of information into meaningful wholes

Closure

Gestalt principle stating that we fill in gaps to perceive complete objects

Figure and ground

Gestalt principle of organizing visual fields into objects (figures) that stand out from their background (ground)

Proximity

Gestalt principle that objects close together are perceived as a group

Similarity

Gestalt principle that objects that are similar in shape

Attention

Focusing awareness on a narrowed range of stimuli

Selective attention

Focusing conscious awareness on a particular stimulus while ignoring others

Cocktail party effect

Ability to focus on one stimulus (like your name) in a noisy environment while filtering out background stimuli

Inattentional blindness

Failing to see visible objects when attention is directed elsewhere

Change blindness

Failing to notice changes in the environment

Binocular depth cues

Depth cues that require both eyes

Retinal disparity

Binocular cue for depth perception; the brain compares images from each eye to judge distance

Convergence

Binocular cue where eyes turn inward to focus on near objects; more inward = closer perception

Monocular depth cues

Depth cues available to one eye alone

Relative clarity

Monocular cue: hazy or unclear objects are perceived as farther away

Relative size

Monocular cue: if two objects are similar

Texture gradient

Monocular cue: gradual change from coarse to fine texture signals increasing distance

Linear perspective

Monocular cue: parallel lines appear to converge as they recede into the distance

Interposition

Monocular cue: objects that overlap others are perceived as closer

Apparent movement

Perceiving motion in a stationary object