sensation and perception ap psych

Sensation

sensory receptors and nervous system receive and represent stimuli from our environment

Absolute Threshold

The minimum stimulation needed to detect a stimulus 50% of the time.

Just-Noticeable Difference (Difference Threshold)

The smallest change in a stimulus that can be detected.

Weber's Law

The principle that the JND is a constant proportion of the original stimulus.

Sensory Adaptation

Reduced sensitivity to unchanging stimuli over time.

Sensory Interaction

The principle that one sense may influence another.

Synesthesia

A condition where stimulation of one sense leads to involuntary experiences in another.

Wavelengths

The distance between peaks of a wave; determines color or pitch.

Retina

Light-sensitive layer at the back of the eye where images are projected.

Blind Spot

The point where the optic nerve leaves the eye; no receptors there.

Visual Nerve (optic nerve)

Transmits visual information from the retina to the brain.

Lens

Focuses light onto the retina by changing shape.

Accommodation

The lens changing shape to focus on near or far objects.

Nearsightedness

A condition where close objects are seen clearly but distant ones are blurry.

Farsightedness

A condition where distant objects are seen clearly but close ones are blurry.

Fovea

The central point of focus on the retina; contains most cones.

Photoreceptors

Specialized cells (rods and cones) that detect light.

Transduction

The process of converting sensory input into neural signals.

Rods

Photoreceptors that detect light and dark; work well in dim light.

Cones

Photoreceptors that detect color and detail; work best in bright light.

Trichromatic Theory

The idea that color vision is based on three color receptors (red

Opponent-Process Theory

Color perception depends on opposing retinal processes (red-green

Afterimages

Visual sensations that remain after the stimulus is removed.

Ganglion Cells

Neurons that form the optic nerve and carry visual information.

Dichromatism

Color blindness where one cone type is missing.

Monochromatism

Complete color blindness; seeing only shades of gray.

Prosopagnosia

Inability to recognize faces.

Blindsight

The ability to respond to visual stimuli without conscious awareness.

Pitch

The highness or lowness of a sound

Amplitude

The height of a sound wave; determines loudness.

Olfactory System (Olfaction)

The sensory system responsible for smell.

Thalamus

The brain’s sensory relay station (except for smell).

Pheromones

Chemical signals that affect behavior or physiology of others.

Gustation

The sense of taste.

Taste Receptors

Sensory cells that detect sweet

Umami

The savory taste sensation

Supertasters

People with extra taste buds; very sensitive to taste.

Medium Tasters

People with average taste sensitivity.

Nontasters

People with fewer taste buds; low taste sensitivity.

Gate Control Theory

The idea that pain signals can be blocked or allowed through spinal “gates.”

Phantom Limb Sensation

The perception of sensations in an amputated limb.

Vestibular Sense

The sense of balance and body position.

Semicircular Canals

Structures in the inner ear that detect rotational movement.

Kinesthesis

The sense of body part movement and position.

Perception

The process of organizing and interpreting sensory information.

Bottom-Up Processing

Perception based on sensory input building upward to the brain.

Top-Down Processing

Perception guided by experience and expectations.

Selective Attention

Focusing on one stimulus while ignoring others.

Cocktail Party Effect

Ability to focus on one voice and still notice your name elsewhere.

Inattentional Blindness

Failing to see visible objects when attention is elsewhere.

Change Blindness

Failing to notice changes in the environment.

Gestalt Psychology

The study of how we perceive whole patterns

Figure and Ground

The organization of the visual field into objects (figure) and background (ground).

Similarity

Grouping similar items together in perception.

Binocular Cues

Depth cues that require both eyes.

Convergence

Inward eye movement when focusing on close objects.

Retinal Disparity

Difference between images from each eye; gives depth perception.

Monocular Cues

Depth cues available to each eye separately.

Relative Clarity

Clearer objects appear closer; hazy ones farther away.

Relative Size

Smaller objects appear farther away if similar in size.

Texture Gradient

Objects with less detail appear farther away.

Linear Perspective

Parallel lines appear to converge with distance.

Interposition

Closer objects block the view of those farther away.

Perceptual Constancies

Perceiving objects as stable despite changes in lighting or angle.

Apparent Motion

Perceiving movement when none exists.