Ap Psyc Unit 4 Sensation

Sensation

The process by which sensory receptors and the nervous system detect and represent stimulus energy

Psychophysics

The study of how physical stimuli relate to our psychological experiences of them.

Transduction

The conversion of stimulus energy into neural impulses that the brain can process.

Absolute threshold

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

Difference threshold (JND)

The minimum difference between two stimuli that can be detected 50% of the time

Signal detection theory

The theory that detecting a faint stimulus depends on the signal, background noise, and factors like expectations, experience, and fatigue.

Subliminal stimuli

Stimuli presented below the level needed for conscious awareness.

Weber’s law

The principle that the minimum noticeable difference between stimuli is a constant proportion of the original stimulus.

Sensory adaptation

A decrease in sensitivity after constant exposure to an unchanging stimulus.

Light

Electromagnetic energy that can be detected by the eyes.

Wavelengths

The distances between corresponding points on consecutive waves, with visible wavelengths determining color.

Frequency

The number of complete waves passing a point per second.

Amplitude

The height or intensity of a wave, related to brightness in light and loudness in sound.

Hue

The color we perceive, determined by the wavelength of light.

Pupil

The opening in the center of the iris that allows light into the eye.

Iris

The colored muscle surrounding the pupil that controls its size.

Cornea

The clear outer covering of the eye that helps focus incoming light.

Lens

The flexible structure behind the pupil that focuses light onto the retina.

Accommodation

The process by which the lens changes shape to focus on nearby or distant objects.

Retina

The light-sensitive layer at the back of the eye containing rods, cones, and other neurons.

Rods

Retinal receptors that work best in dim light and detect black, white, and gray.

Cones

Retinal receptors concentrated near the center of the retina that detect color and fine detail in bright light.

Fovea

The central area of the retina where cones are concentrated and vision is sharpest.

Optic nerve

The nerve that carries visual information from the retina to the brain.

Blind spot

The point where the optic nerve leaves the retina, creating an area without visual receptors.

Ganglion cells

Retinal cells that receive processed visual information and transmit it toward the brain.

Bipolar cells

Retinal cells that relay information from rods and cones to ganglion cells.

Feature detectors

Neurons that respond to specific visual features such as lines, edges, angles, and movement.

Dark adaptation

The process by which the eyes become more sensitive after entering darkness.

Light adaptation

The process by which the eyes adjust to bright light and become less sensitive.

Trichromatic theory

The theory that color vision depends on three types of cones sensitive to different ranges of wavelengths.

Trichromats

People with three functioning types of color-sensitive cones.

Opponent-process theory

The theory that color vision uses opposing processes such as red-green, blue-yellow, and black-white.

Afterimage

A visual image that remains after looking away from the original stimulus, often showing an opposing color.

Colorblindness

A reduced ability to distinguish certain colors because of missing or malfunctioning cone systems.

Dichromats

People who have only two functioning types of color-sensitive cones.

Monochromats

People with no functioning cones or only one functioning cone type, resulting in little or no color discrimination.

Audition

The sense of hearing.

Sound waves

Vibrations that travel through a medium, such as air, and can be detected by the ears.

Pitch

The perceived highness or lowness of a sound, mainly determined by frequency.

Decibel (dB)

A unit used to measure sound intensity.

Timbre

The quality of a sound that makes it distinguishable from another sound with the same pitch and loudness.

Overtones

Additional frequencies above a sound’s fundamental frequency that help determine its tone quality.

Middle ear

The chamber containing three tiny bones that transmit and amplify vibrations toward the cochlea.

Ossicles

The three middle-ear bones—the hammer, anvil, and stirrup—that amplify sound vibrations.

Oval window

The membrane that receives vibrations from the stirrup and transfers them into the cochlea.

Cochlea

The coiled, fluid-filled inner-ear structure that converts sound vibrations into neural signals.

Basilar membrane

The membrane inside the cochlea that vibrates at different locations in response to different sound frequencies.

Organ of Corti

The structure inside the cochlea containing hair cells that convert vibrations into neural signals.

Auditory nerve

The nerve that carries sound information from the cochlea to the brain.

Round window

A flexible membrane in the cochlea that allows fluid movement as sound vibrations travel through it.

Place theory

The theory that pitch depends on where the basilar membrane is stimulated.

Frequency theory

The theory that pitch is detected through the rate at which auditory nerve impulses match a sound’s frequency.

Volley principle

The theory that groups of neurons take turns firing to represent frequencies too high for one neuron to match alone.

Gate-control theory

The theory that the spinal cord can block or allow pain signals to reach the brain.

Taste buds

Sensory structures containing receptor cells that detect different tastes.

Papillae

Small bumps on the tongue that contain or support many taste buds.

Olfactory epithelium

Tissue inside the nasal cavity containing receptors that detect odors.

Olfactory bulb

A brain structure that receives and processes information from smell receptors.

Vomeronasal organ (VNO)

A sensory structure involved in detecting chemical signals in many animals.

Pheromones

Chemicals released by animals that can influence the behavior or physiology of others of the same species.

Kinesthesis (kinesthetic sense)

The sense of the position and movement of individual body parts.

Golgi tendon organs

Sensory receptors that detect tension in muscles and tendons.

Stretch receptors

Receptors that detect stretching in body tissues and help provide information about body position.

Vestibular sense

The sense of balance and body movement provided by structures in the inner ear.

Semicircular canals

Inner-ear structures that detect rotational movements of the head.

Vestibular sacs

Inner-ear structures that detect head position relative to gravity and linear acceleration.

Sensory interaction

The principle that one sense can influence another, such as smell affecting taste.

Synesthesia

A condition in which stimulation of one sensory system triggers an experience in another, such as hearing sounds and perceiving colors.