Sensation & Perception Notes

Sensation

The stimulation of sensory receptors and transmission of sensory information to the central nervous system (CNS).

Perception

The psychological process by which we interpret sensory information.

Absolute threshold

The weakest amount of stimulus that can be sensed.

Difference threshold

The minimum amount of difference that can be distinguished between two stimuli, also known as just noticeable difference (jnd).

Signal detection theory

A theory that explains how we distinguish sensory stimuli, taking into account the setting, physical state, mood, and expectations.

Sensory adaptation

The process of becoming more sensitive to weak stimuli and less sensitive to unchanging stimuli.

Just noticeable difference (jnd)

The minimum difference in stimulus intensity that a person can detect 50% of the time.

Pupil

Opening in eye changes shape based on light & emotions

Lens

Adjusts to the distance of an object by changing its thickness; focuses on objects.

Retina

The part of the eye that takes focused light and images, acting like the film of a camera.

Photoreceptors

Neurons in the retina that carry visual information to the brain via the optic nerve.

Rods

Photoreceptors that allow us to see in black and white and are sensitive to light.

Cones

Photoreceptors responsible for color vision.

Optic nerve

Transmits neural impulses from the eye to the brain.

Blind spot

The area where the optic nerve leaves the eye, lacking photoreceptors.

Visual acuity

The sharpness of vision.

Afterimage

A visual sensation that occurs after the original stimulus.

Complimentary colors

Colors that are opposite each other on the color wheel, like red and green.

Color blindness

A condition caused by missing or defective cones in the eyes.

Cochlea

A snail-shaped structure that produces nerve impulses from sound vibrations.

Auditory nerve

A bundle of nerves carrying sound information from the cochlea to the brain.

Conductive deafness

Deafness caused by damage to the middle ear.

Sensorineural deafness

Deafness caused by damage to the inner ear or auditory nerve, affecting certain frequency sounds.

Olfactory nerve

Transmits odors to the limbic system of the brain, contributing to taste.

Taste

Four basic taste qualities: sweetness, sourness, saltiness, and bitterness, plus umami (savory meat flavor).

Flavor of food

A combination of odor, texture, temperature, and taste.

Skin senses

Includes touch, pain, and temperature, combining pressure, temperature, and pain sensations.

Gate theory

A theory stating that only a small amount of information can be processed by the nervous system at one time, potentially blocking some pain messages.

Gestalt

The experience that comes from organizing bits of information into meaningful wholes.

Proximity

Grouping items together based on their closeness.

Similarity

The tendency to think of similar objects as belonging to each other.

Continuity

The preference for smooth continuous patterns over disrupted ones.

Common fate

The perception that things moving together belong together.

Closure

The ability to perceive a complete image even when some sensory information is missing.

Figure-ground perception

The perception of figures against a background.

Stroboscopic Motion

The perception of movement from rapid progression of images.

Monocular cues

Depth perception that requires only one eye.

Binocular cues

Depth perception that involves the use of both eyes.

Retinal disparity

The difference between the images received from each eye, used to compute distance.

Convergence

A neuromuscular cue where the two eyes move inward for near objects.

Perceptual Constancies

The perception of objects as unchanging even when light and retinal images change.

Color constancy

Tendency to perceive objects as keeping their color regardless of changes in lighting.

Size constancy

Seeing objects as having a constant size despite variations in distance.

Shape constancy

Perceiving objects as having a constant shape, no matter the angle of view.

Brightness Constancy

Tendency to see an object as equally bright despite changes in lighting intensity.

Müller Lyer Illusion

The visual illusion where two lines of the same length appear different due to contextual effects.