psych

Sensation

The process by which sensory receptors and the nervous system receive and represent stimulus energies from the environment.

Perception

The process of organizing and interpreting sensory information to recognize meaningful objects and events.

Absolute Threshold

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

Just-Noticeable Difference (JND)

The smallest change in a stimulus that can be detected 50% of the time.

Weber’s Law

To perceive a difference between two stimuli, they must differ by a constant minimum percentage, not a fixed amount.

Transduction

The conversion of sensory energy (like light or sound) into neural impulses.

Sensory Adaptation

Diminished sensitivity as a result of constant stimulation.

Sensory Interaction

The principle that one sense may influence another.

Synesthesia

A condition in which one kind of sensory input involuntarily triggers another.

Lens

Focuses light onto the retina.

Retina

Light-sensitive layer at the back of the eye; contains rods and cones.

Fovea

Central point of sharpest vision.

Optic Nerve

Carries visual info from eye to brain.

Blind Spot

Area where optic nerve leaves the eye — no receptor cells.

Rods

Detect black, white, and gray; work best in dim light.

Cones

Detect color; function in daylight.

Trichromatic Theory

Three cone types (red, green, blue) combine to produce color vision.

Opponent-Process Theory

Color perception is based on opposite color pairs (red–green, blue–yellow).

Afterimages

Visual image that remains after a stimulus is removed.

Accommodation

Process by which the lens changes shape to focus near or far objects.

Nearsightedness (Myopia)

Distant objects blurry (eyeball too long).

Farsightedness (Hyperopia)

Close objects blurry (eyeball too short).

Prosopagnosia

Inability to recognize faces (“face blindness”).

Dichromatism

Color blindness for one pair of colors (red-green confusion).

Monochromatism

Total color blindness; only sees black, white, gray.

Blindsight

Ability to respond to visual info without consciously seeing it.

Amplitude

Determines loudness (height of waves).

Wavelength

Determines pitch (distance between peaks).

Frequency Theory

Whole basilar membrane vibrates with the sound’s frequency—explains low pitches.

Place Theory

Different pitches activate different places on the cochlea’s basilar membrane—explains high pitches.

Volley Theory

Groups of neurons fire alternately for mid-range pitches.

Sound Localization

Determining direction of sound using differences between ears.

Sensorineural Deafness

Damage to inner ear (cochlea/hair cells).

Conduction Deafness

Damage to outer/middle ear prevents sound from reaching inner ear.

Gustation (Taste)

Sense of sweet, sour, salty, bitter, umami.

Olfaction (Smell)

Sense of smell.

Pheromones

Chemical signals that affect behavior.

Kinesthetic Sense

Awareness of body position and movement.

Vestibular Sense

Balance and spatial orientation; relies on semicircular canals in inner ear.

Phantom Limb

Sensation from a missing body part.

Supertaster

Person with extra taste buds—more sensitive to flavors.

Gate Control Theory

Spinal 'gate' controls pain messages; rubbing can reduce pain signals.

Gestalt Principles

Principles of perception that demonstrate how we group and interpret visual information.

Bottom-Up Processing

Sensory input builds perception from raw data.

Top-Down Processing

Prior knowledge and expectations shape perception.

Selective Attention

Focusing on one thing while ignoring others.

Cocktail Party Effect

Ability to detect your name in a noisy room.

Inattentional Blindness

Failing to notice something visible when focused elsewhere.

Change Blindness

Failing to notice changes in the environment.

Perceptual Set

Mental predisposition to perceive something a certain way.

Schema

Mental framework that organizes information.

Phi Phenomenon

Illusion of movement created by flashing lights.

Stroboscopic Movement

Perceived motion from rapid still images.

Autokinetic Effect

Stationary point of light appears to move in darkness.

Perceptual Constancies

Objects perceived as unchanging despite changes in lighting, angle, or distance.

Depth Cues

Visual information that helps perceive distance.

Monocular Depth Cues

Depth cues that require one eye.

Binocular Depth Cues

Depth cues that involve two eyes.