PYSCH 110 Ch. 4

Sensation

the activation of the sense organs by a source of physical energy

Perception

the sorting out, interpretation, analysis, and integration of stimuli by the sense organs and brain

Stimulus

energy that produces a response in a sense organ

Absolute threshold

the lowest intensity of a stimulus that an organism can detect

Difference threshold

the smallest level of added or reduced stimulation required to sense that a change in stimulation has occurred

Cornea

the transparent protective window at the front of the eye

Iris

the colored part of the eye

Pupil

the dark hole in the center of the iris

Retina

part of the eye that converts the electromagnetic energy of light to electrical impulses

Rods

thin, cylindrical cells that are highly sensitive to light (black and white perception) and good at detecting light

Cones

cone-shaped cells that are responsible for sharp focus and color perception, particularly in bright light

Peripheral vision

seeing objects that are outside the main center of focus

Optic nerve

a bundle of ganglion axons that carry visual information to the brain

Feature detectors

specialized neurons that are activated only by visual stimuli having specific features, such as a particular shape or pattern

Trichromatic theory of color of vision

there are 3 kinds of cones in the retina, each of which responds primarily to a specific range of wavelengths

Sound localization

the process by which we identify the direction from which a sound is coming

Sound

the movement of air molecules brought about by a source of vibration

Eardrum

the part of the ear that vibrates when sound waves hit it

Inner ear

changes the sound vibrations into a form transmittable to the brain

Cochlea

a coiled tube in the ear filled with fluid that vibrates in response to sound

Basilar membrane

a vibrating structure through the center of the cochlea, containing sense receptors for sound

Hair cells

tiny cells covering the basilar membrane that, when bent by vibrations entering the cochlea, transmit neural messages to the brain

Hyperacusis

a rare disorder where a person is acutely sensitive to sounds that others find tolerable

Place theory of hearing

different areas of basilar membrane respond to different frequencies

Frequency theory of hearing

the entire basilar membrane acts like a microphone, vibrating as a whole in response to a sound

Vestibular system

responds to the pull of gravity and allows us to maintain our balance

Semicircular canals

3 tube like structures of the inner ear containing fluid that sloshes when the head moves, signaling rotational or angular movement to the brain

Gate-control theory of pain

particular nerve receptors in the spinal cord that lead to specific areas of the brain related to pain

Closure

we usually group elements to form enclosed or complete figures rather than open ones

Proximity

we perceive elements that are closer together as grouped together

Similarity

elements that are similar in appearance

Simplicity

when we observe a pattern, we perceive it in the most basic straightforward manner that we can

Top-down processing

perception is guided by higher level knowledge, experience, expectations, and motivations

Bottom-up processing

perception that consists of recognizing and processing information from individual components of a stimuli and moving to the perception of the whole

Depth perception

the ability to view the world in 3 dimensions and to perceive distance

Perceptual constancy

our understanding that physical objects are unvarying and consistent even though sensory input about them may vary

Apparent movement

the perception that a stationary object is moving

Visual illusions

physical stimuli that consistently produce errors in perception

Subliminal perception

the perception of messages about which we have no awareness

Extrasensory perception

perception that does not involve our known senses