AP Sensation 1.6.A & 1.6.B

Sensation

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

Sensory receptors

Sensory nerve endings that respond to stimuli.

Perception

The process by which the brain organizes and interprets sensory input.

Bottom-up processing

Information processing that begins with the sensory receptors and works up to the brain's integration of sensory information.

Top-down processing

Information processing guided by higher-level mental processes, such as when we construct perceptions drawing on our experience and expectations.

Absolute threshold

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

Signal detection theory

A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation.

Subliminal

Stimuli you cannot consciously detect 50% of the time.

Difference Thresholds

The minimum difference between two stimuli required for detection 50% of the time.

Sensory adaptation

Diminished sensitivity as a consequence of constant stimulation.

Sensory interaction

The sensory systems constantly work together in a process.

Synesthesia

An experience of sensation in which one system of sensation is experienced through another.

Cornea

The eye's clear, protective outer layer, covering the pupil and iris.

Pupil

The adjustable opening in the center of the eye through which light enters.

Iris

A ring of muscle tissue that forms the colored portion of the eye around the pupil and controls the size of the pupil opening.

Lens

The transparent structure behind the pupil that changes shape to help focus images on the retina.

Accommodation

The process by which the eye's lens changes shape to focus images of near or far objects on the retina.

Retina

A thin, photosensitive layer of nerve tissue that lines the back inside of the eye and converts incoming light into electrical signals sent to the brain.

Rods

Retinal receptor cells that lie in the periphery of the eye; detect shape and black, white, and gray, not color.

Trichromatic theory

Explains how cones detect color at the retina.

Opponent-process theory

Explains how the brain processes color signals afterward.

Optic nerve

The nerve that carries neural impulses from the eye to the brain.

Blindsight

A person responds to visual stimuli without consciously perceiving having seen it.

Binocular Fusion

Combining two images from each eye into one.

Retinal Disparity

The difference between the two retinal images helps us perceive depth.

Prosopagnosia

Inability to recognize familiar faces, despite otherwise normal vision.

Outer ear

Part of the ear that catches sound waves and funnels them towards the eardrum.

Eardrum

Membrane that vibrates when struck by sound waves.

Middle ear

Contains three tiny bones (hammer, anvil, stirrup) that transmit vibrations to the cochlea.

Cochlea

Snail-shaped tube in the inner ear where vibrations are converted into electrical signals.

Basilar membrane

Membrane in the cochlea that ripples and bends hair cells in response to vibrations.

Hair cells

Cells that trigger impulses in adjacent nerve cells when moved by vibrations.

Auditory nerve

Carries neural messages from the hair cells to the thalamus and auditory cortex.

Sound localization

Brain's ability to determine the location of a sound source based on timing and intensity differences.

Place theory

Theory that certain hair cells are activated by specific frequencies.

Frequency theory

Theory that neurons fire in unison with vibrations to match their frequency.

Volley theory

Theory that groups of auditory neurons fire in rapid succession to encode high-frequency sounds.

Conductive hearing loss

Hearing loss due to physical damage to parts of the middle or outer ear.

Sensorineural hearing loss

Hearing loss due to malfunctioning cochlear receptors or auditory nerves.

Olfactory stimuli

Substances that are processed and transduced by structures in the nose and brain.

Taste types

Includes sweet, sour, salty, bitter, umami, and oleogustus.

Taste buds

Clusters in the papillae that contain taste receptor cells detecting chemicals in saliva.

Gustatory cortex

Brain area where signals from taste receptor cells are processed and consciously experienced as taste.

Kinesthesis

Sense of one's body movement.

Mechanoreceptors

Cells that transduce pressure, vibration, and stretch into neural signals.

Semicircular canals

Three fluid-filled canals that inform the brain about balance and movement.

Proprioceptors

Include muscle spindles, Golgi tendon organs, and joint receptors that send feedback to the brain.