sensations

Absolute Threshold

The smallest level of stimulus that can be detected by the senses at least 50% of the time.

Just Noticeable Difference (JND)

The minimal change in a stimulus that can be detected.

Transduction

The process of converting sensory stimuli into neural signals that the brain can interpret.

Thalamus

A brain structure that acts as a relay center, sending sensory information (except smell) to appropriate areas of the brain.

Lens

A transparent structure that focuses light on the retina.

Accommodation

The process by which the lens changes shape to focus near or far objects.

Retina

The light-sensitive layer of cells at the back of the eye containing rods and cones.

Rods and Cones

Photoreceptor cells; rods detect black, white, and gray, while cones detect color and fine detail.

Blind Spot

The point where the optic nerve exits the eye, creating a spot with no photoreceptors.

Occipital Lobe (Visual Cortex)

The part of the brain responsible for processing visual information.

Opponent-Process Theory

A theory of color vision stating that color is processed in opposing pairs (red-green, blue-yellow, black-white).

Trichromatic Theory

A theory of color vision based on three types of cone cells sensitive to red, green, and blue light.

Light/Dark Adaptation

The ability of the eyes to adjust to changes in light levels.

Prosopagnosia

The inability to recognize faces.

Blindsight

A condition where individuals can respond to visual stimuli without consciously perceiving them.

Hair Cells

Sensory receptors in the cochlea that detect sound vibrations.

Ossicles

Tiny bones in the middle ear (malleus, incus, and stapes) that amplify sound.

Tympanic Membrane

The eardrum.

Temporal Lobes (Auditory Cortex)

The brain region responsible for processing auditory information.

Sound Waves

Variations in air pressure that travel as waves; characterized by wavelength and amplitude.

Sound Localization

The ability to determine the location of a sound in space.

Frequency Theory

Suggests that the frequency of auditory nerve impulses corresponds to the frequency of a tone.

Place Theory

Proposes that different areas of the cochlea are activated by different frequencies.

Conduction Deafness

Hearing loss caused by damage to the middle ear structures.

Sensorineural Deafness

Hearing loss caused by damage to the cochlea or auditory nerve.

Phantom Pain

The perception of pain in a limb or part of the body that has been amputated.

Vestibular Sense

The sense of balance and spatial orientation, controlled by semicircular canals in the inner ear.

Kinesthetic Sense

The awareness of the position and movement of body parts.

Cutaneous (Touch) Senses

Sensations of pressure, temperature, and pain perceived through the skin.

Gate-Control Theory

A theory explaining how the nervous system blocks or allows pain signals to pass to the brain.

Anosmia

The inability to perceive odors.

Pheromones

Chemicals secreted by organisms that can influence the behavior or physiology of others.

Taste Buds

Sensory organs that detect taste (sweet, sour, salty, bitter, umami).

Synesthesia

A condition in which stimulation of one sensory pathway leads to automatic, involuntary experiences in a second sensory pathway.