Unit 1B

Sensation

the process by which our sensory receptors receive stimuli from our environment

Transduction

process by which sensory stimuli are converted into neural signals

Absolute threshold 

minimum level of stimulus intensity needed for a stimulus to be detected

Sensory adaptation 

process by which our sensory receptors become less responsive to constant stimuli over time

Just noticeable difference 

the smallest amount by which two stimuli must differ for an individual to detect a difference between them

Weber’s law

the principle that states that the just-noticeable difference between two stimuli is a function of the magnitude of the original stimulus

Sensory interaction

the process by which our five senses work with and influence each other

Synesthesia

a phenomenon that causes sensory crossovers, such as tasting colors or feeling sounds

Iris

a muscle that controls how much light enters the eye

Cornea

a transparent outer covering of the eye

Lens

it focuses light on the retina

Pupil

a hole that allows light to enter the eye

Retina

it contains visual sensory receptors 

Fovea

it contains most of the eyes cones

Blind spot

where the optic nerve leaves they eye (no receptors)

Optic nerve

it takes messages to the brain

Rods

photoreceptors in the retina that see black and white; responsible for night vision

Ganglion cells

specialized neurons in the retina that collect visual information from bipolar cells and transmit it to the brain

Cones

responsible for color vision and sharp vision in bright light conditions

Accommodation

when the lens adjust its shape to bend and focus the light

Nearsightedness

nearby objects are seen more clearly than far objects

Farsightedness

faraway objects are seen more clearly than near objects

Visual transduction

the conversion of light energy into neural signals within the photoreceptor cells (rods and cones) of the retina

Photoreceptors

specialized cells in the retina that convert light energy into electrical signals, allowing us to see

Red wavelengths 

long wavelengths, 620-750 nm

Green wavelengths

medium wavelengths, 495-570 nm

Blue wavelengths

short wavelengths, 450-495 nm

Light and dark adaptation

when the eyes adjust from darkness to bright light or from bright light to darkness

Color vision

the ability to perceive and distinguish different colors

Trichromatic theory

a theory of color vision that suggests the human eye has three types of cones, each sensitive to different wavelengths of light (red, green, and blue)

Opponent process theory 

a theory where we see color through opposing pairs of colors; when one color in a pair is activated, the other is inhibited (red-green, black-white)

Afterimages 

a visual illusion where you continue to see an image after the original stimulus is removed

Dichromatism

partial color blindness in which the eye contains only two types of cone photopigment instead of the typical three

Monochromatism

a rare form of complete color blindness where a person sees only in shades of gray, black, and white

Prosopagnosia

face blindness

Blindsight

the phenomenon where a person can respond to visual stimuli they are not consciously aware of seeing

Wavelength

How fast the wave vibrates; determines the pitch of the sound

Amplitude

Height of the wave; tells loudness of the sound

Place theory

Theory that explains pitch perception as a result of different locations

Volley theory

Theory that explains pitch perception as a result of neurons firing at alternating rates

Frequency theory 

Theory that explains pitch perception as a result of hair cells vibrating at the same rate as a sound wave

Sound localization

the process by which we perceive and identify the specific location or direction of a sound source in our environment

Conduction deafness

type of hearing loss that causes damage to the outer or middle ear

Sensorineural deafness

Type of hearing loss from damage to hair cells or auditory nerve ; the inner ear or actual hearing nerve becomes damaged

Olfaction

Chemical sense that allows an organism to detect odors

Pheromones

Chemical signals that’s released outside the body and is used to influence the behavior of others

Gustation

Chemical sense that involves taste buds on the tongue

Supertaster

Has extremely sensitive taste buds, highly sensitive to bitter foods, women are more likely to have it

Medium taster

Has the average number of taste buds, taste bitter substance at an average level

Nontaster 

Unable to taste bitter compounds, 25% of the population 

Gate control theory

A theory that the spinal cord contains a neurological "gate" that blocks pain signals from reaching the brain or allows them to pass through, influencing the perception of pain

Phantom limb

The ability to feel sensations and pain in a limb that no longer exists

Vestibular sense

the body's system for balance, movement, and spatial orientation, located in the inner ear

Kinesthetic sense 

the body's ability to sense its own position, movement, and location of its parts without relying on vision