AP Psych - Sensation and Perception

Absolute Threshold

The minimum amount of stimulus needed for the body's sensory receptors to detect; activates sensory neurons.

Accommodation (Perceptual)

Process in which the sensory system adjusts focus to perceive stimuli more clearly.

Binocular Cues

Depth cues that require both eyes to perceive distance and three-dimensional space.

Blind Spot

Area on the retina where the optic nerve exits; no photoreceptors, so no vision there.

Bottom-Up Processing

Perception that starts with sensory input and builds up to a full understanding; no prior knowledge used.

Cochlea

Spiral cavity in the inner ear that converts sound vibrations into nerve impulses.

Conduction Deafness

Hearing loss caused by blockage or damage to the outer or middle ear that prevents sound from reaching the inner ear.

Cones

Photoreceptor cells in the retina that detect color and fine detail; about 6 million in each eye.

Convergence

Binocular cue; eyes move inward (cross) when focusing on a close object.

Cornea

Transparent dome-shaped front layer of the eye that covers the iris and pupil.

Dark Adaptation

The eyes’ increased sensitivity to light in low-light conditions; takes 20–30 minutes for full adjustment.

Difference Threshold

The smallest change between two stimuli that can be detected (e.g., noticing music volume increasing).

Feature Detector

Specialized neurons in the visual cortex that identify specific features like lines, angles, or motion.

Fovea

The central area of the retina with the sharpest vision; highest concentration of cones.

Frequency Theory

Theory that pitch perception depends on the frequency at which the basilar membrane vibrates.

Gate Control Theory

Explains how pain signals are regulated in the spinal cord; “gates” can block or allow pain signals to the brain.

Habituation

The brain stops paying attention to constant stimuli; thalamus filters them out, but neurons still respond.

Hue

A color or shade determined by the wavelength of light.

Inattentional Blindness

Failure to notice something visible because attention is focused elsewhere.

Iris

Colored ring-shaped membrane behind the cornea; controls the size of the pupil to regulate light intake.

Lens

Transparent structure behind the iris that focuses light onto the retina.

Monocular Cues

Depth cues available to each eye alone, such as relative size, texture gradient, and linear perspective.

Relative Clarity

Hazy objects appear farther away.

Relative Size

Smaller retinal image = object perceived as farther away.

Texture Gradient

Textures become finer as distance increases.

Linear Perspective

Parallel lines appear to converge in the distance.

Interposition

One object blocking another appears closer.

Olfaction

The sense of smell.

Opponent Process Theory

Theory that color vision is based on three opposing pairs

Optic Nerve

Bundle of fibers carrying visual information from the retina to the occipital lobe; crosses visual fields.

Perception

Mental process of organizing sensory information into meaningful patterns.

Perceptual Constancy

Tendency to perceive objects as having constant size, shape, and color despite changes in the stimulus.

Pheromones

Chemical signals secreted by one individual and received by another of the same species.

Phantom Limb Sensation

Feeling sensations in an amputated limb due to the brain’s representation of the body.

Pitch

Perceived highness or lowness of sound; depends on wave frequency, measured in Hertz (Hz).

Place Theory

Theory that pitch depends on the location of vibration along the basilar membrane in the cochlea.

Pupil

Adjustable opening in the center of the iris that allows light to enter the eye.

Retina

Light-sensitive layer at the back of the eye; converts light into neural signals.

Retinal Disparity

Slight difference between the images seen by each eye; a binocular cue for depth.

Rods

Photoreceptors sensitive to light levels (not color); enable vision in dim light and peripheral vision.

Schema

Framework of knowledge or expectations that organizes and interprets information.

Sensorineural Deafness

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

Sensation

The process of detecting physical energy (stimulus) from the environment through sensory organs.

Sensory Adaptation

Diminished sensitivity to constant stimulation; sensory neurons stop firing after a while.

Shape Constancy

Perceiving an object’s shape as stable even when the angle of view changes.

Signal Detection Theory

Explains how we distinguish important stimuli (signals) from background noise.

Size Constancy

Perceiving an object as the same size even when its retinal image changes due to distance.

Subliminal Perception

Processing sensory information below the level of conscious awareness; can subtly influence thoughts or behavior.

Taste Buds

Sensory receptors for taste (sweet, sour, salty, bitter, umami, oleogustus).

Top-Down Processing

Perception that uses prior knowledge, context, and expectations to interpret sensory information.

Transduction

Conversion of sensory information into neural signals for the brain to process.

Trichromatic Theory

Theory that three types of cones (red, green, blue) combine to produce all colors.

Vestibular Sense

Sense of balance and body position; located in the inner ear’s semicircular canals.

Weber’s Law

Principle that the difference threshold is a constant proportion of the original stimulus.