Sensation and Perception: An Overview of Senses

Sensation

Detecting physical energy (stimuli) from the environment and turning it into neural signals.

Psychophysics

Study of how physical energy relates to our psychological experience.

Absolute Threshold

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

Signal Detection Theory

Detecting a signal depends on experience, expectation, motivation, and fatigue.

Difference Threshold (JND)

Smallest change in stimulus you can detect 50% of the time.

Weber's Law

To perceive a difference, stimuli must differ by a constant proportion (not amount).

Sensory Adaptation

Reduced sensitivity after constant exposure to a stimulus.

Transduction

Converting physical energy (like light or sound) into neural signals.

Wavelength

Distance between peaks of a wave; determines color.

Hue

The color we see (determined by wavelength).

Intensity

Brightness (determined by wave amplitude).

Pupil

Small opening that lets light in.

Iris

Colored muscle that controls the size of the pupil.

Lens

Focuses light onto the retina.

Accommodation

Lens changes shape to focus near or far objects.

Retina

Light-sensitive layer at the back of the eye where transduction happens.

Acuity

Sharpness or clarity of vision.

Nearsightedness

Can see near, not far (image focuses in front of retina).

Farsightedness

Can see far, not near (image focuses behind retina).

Rods

Detect black, white, gray; good for night vision and peripheral vision.

Cones

Detect color and fine detail; work best in bright light.

Optic Nerve

Sends visual information from the eye to the brain.

Blind Spot

Where the optic nerve leaves the eye—no receptor cells there.

Ganglion Cells

Neurons that collect info from rods/cones and form the optic nerve.

Feature Detector

Brain cells that respond to specific visual features (lines, angles, movement).

Young-Helmholtz Trichromatic Theory

We see color through red, green, and blue cones.

Opponent-Process Theory

Color is seen through opposing pairs (red-green, blue-yellow, black-white).

Color Constancy

Perceiving familiar objects as the same color despite lighting changes.

Audition

The sense of hearing.

Frequency

Number of wavelengths per second; determines pitch.

Pitch

How high or low a sound is.

Decibels

Measurement of sound intensity (volume).

Place Theory

Different sound pitches stimulate different places on the cochlea.

Frequency Theory

Pitch is determined by how fast hair cells fire.

Volley Principle

Hair cells alternate firing to detect high frequencies.

Sense of Touch

Skin senses: pressure, warmth, cold, and pain.

Gate Control Theory

The spinal cord has a "gate" that can block pain signals or let them through.

Five Basic Tastes

Sweet, sour, salty, bitter, umami (savory).

Taste Buds

Sense organs on the tongue that contain taste receptor cells.

Taste Receptor Cells

Detect chemical molecules from food.

Sensory Interaction

One sense influences another (e.g., smell affects taste).

Olfaction

Sense of smell.

Olfactory Receptor Cells

Detect airborne chemicals in the nose.

Olfactory Bulb

Brain structure that processes smell.

Olfactory Nerve

Carries smell info from the nose to the brain.

Kinesthesis

Sensing body part position and movement.

Vestibular Sense

Sensing balance and body position through the inner ear.

Semicircular Canals

Inner ear structures that help maintain balance.

Vestibular Sacs

Fluid-filled sacs that help detect gravity and motion.

Conduction Deafness

Hearing loss due to damage in outer/middle ear (mechanical problem).

Sensorineural Deafness

Hearing loss from damage to inner ear or auditory nerve (nerve problem).

Dichromatism

Color blindness with only two functioning color receptors.

Monochromatism

Total color blindness (only one or no functioning cone types).

Synesthesia

A condition where one sense triggers another (e.g., seeing colors when hearing music).