Unit 1: Sensation and Perception (Modules 1.6a - 1.6d)

Vocabulary practice flashcards covering basic sensation concepts, vision, audition, skin and chemical senses, body position, and sensory interaction.

Sensation

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

Perception

The process of organizing and interpreting sensory information, enabling us to recognize meaningful objects and events.

Bottom-Up Processing

Information processing that starts with the sensory input, where the brain attempts to understand and make sense of raw stimuli.

Top-Down Processing

Information processing guided by higher-level mental processes, experience, and expectations.

Transduction

The conversion of one form of energy into another, such as transforming stimulus energies into neural impulses that the brain can interpret via three basic steps: receive, transform, and deliver.

Psychophysics

The study of relationships between the physical characteristics of stimuli, such as their intensity, and our psychological experience of them.

Absolute Threshold

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

Difference Threshold (Just Noticeable Difference / JND)

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

Signal Detection Theory

A theory predicting how and when we detect the presence of a faint stimulus amid background stimulation, depending on signal strength and the observer's psychological state (experience, expectations, motivation, and alertness).

Weber's Law

The principle that to be perceived as different, two stimuli must differ by a constant minimum percentage rather than a constant amount (e.g., lights by $8\%$, weight by $2\%$, and tones by $0.3\%$).

Subliminal Stimuli

Stimuli that are below one's absolute threshold for conscious awareness, detected less than $50\%$ of the time.

Priming

The activation, often unconsciously, of certain associations, predisposing one's perception, memory, or response.

Sensory Adaptation

Diminished sensitivity to stimuli as a consequence of constant stimulation, allowing organisms to focus attention on informative changes in the environment.

Wavelength (Light)

The distance from the peak of one light wave to the peak of the next, which determines the hue or color perceived.

Amplitude (Light)

The height of a light wave, which determines the perceived brightness or intensity of the color.

Cornea

The clear, protective outer layer of the eye covering the pupil and iris through which light first enters.

Pupil

The small, adjustable opening in the center of the eye through which light passes.

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 by expanding and contracting.

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 its curvature and thickness to focus near or distant objects on the retina.

Myopia

Nearsightedness; a condition occurring when the lens focuses images on a point in front of the retina, resulting in distant objects appearing blurry while near objects remain clear.

Hyperopia

Farsightedness; a condition resulting from the lens focusing incoming light past the retina.

Retina

The light-sensitive inner surface along the back of the eye containing receptor rods and cones plus neural layers that initiate visual processing.

Rods

Retinal photoreceptors located in the outer periphery that detect black, white, and gray, enable peripheral and twilight vision, and share bipolar cell connections without direct pathways to the brain.

Cones

Retinal photoreceptors concentrated near the center of the retina that function in daylight or well-lit conditions, detect fine detail, produce color sensations, and often have a direct hotline to a single bipolar cell.

Fovea

The central focal point in the retina around which cones cluster, providing the area of greatest visual acuity or sharpness of focus.

Optic Nerve

The nerve comprised of ganglion cell axons that leaves through the back of the eye to carry neural impulses from the eye to the thalamus and visual cortex.

Blind Spot

The optic disk where the optic nerve exits the eye, leaving an area with no photoreceptor cells (rods or cones).

Young-Helmholtz Trichromatic Theory

The theory proposing that the retina contains three different types of color receptors (cones)—most sensitive to red, green, or blue—which produce the perception of any color when stimulated in combination.

Hering Opponent-Process Theory

The theory that cone photoreceptors are paired together (red-green, blue-yellow, white-black) such that activation of one color inhibits activation of the other.

Feature Detectors

Specialized nerve cells located in the visual cortex of the occipital lobe that respond specifically to edges, lines, angles, and movements.

Fusiform Face Area

A brain area located near the temporal lobe by the right ear that enables the perception and recognition of faces.

Parallel Processing

The brain's natural mode of information processing that analyzes multiple aspects of a scene—including motion, form, depth, and color—simultaneously.

Audition

The sense or act of hearing.

Pitch

A tone's experienced highness or lowness, determined by the sound wave's frequency or wavelength.

Auditory Canal

The channel in the outer ear that funnels sound waves from the pinna to the tympanic membrane.

Tympanic Membrane (Eardrum)

A thin layer of tissue separating the outer ear from the middle ear that vibrates in response to sound waves.

Ossicles

The three smallest bones in the human body (the malleus, incus, and stapes) located in the middle ear that amplify and transfer sound wave vibrations to the oval window.

Oval Window

The membrane-covered opening of the cochlea that vibrates when hit by the stapes, causing fluid inside the cochlea to move.

Cochlea

A coiled, bony, fluid-filled tube in the inner ear through which sound waves trigger nerve impulses.

Basilar Membrane

A membrane inside the cochlea lined with hair cells (cilia) that ripple in response to cochlear fluid motion, triggering neural transduction.

Sensorineural Hearing Loss

Hearing loss caused by damage to the cochlea's hair cell receptors or the auditory nerve (also called nerve deafness).

Conduction Hearing Loss

A less common form of hearing loss caused by mechanical damage to the eardrum or the middle ear bones that conduct sound waves to the cochlea.

Cochlear Implant

A medical device for converting sounds into electrical signals and stimulating the auditory nerve via electrodes threaded into the cochlea.

Place Theory

The theory (also known as place coding) that pitch perception is determined by recognizing the specific spot along the basilar membrane that generates a neural signal, best explaining high pitches.

Frequency Theory

The theory (also known as temporal coding) that the brain reads pitch by monitoring the rate of neural impulses traveling up the auditory nerve to match the sound wave's frequency, best explaining low pitches.

Volley Principle

The principle stating that neural cells can alternate firing in rapid succession to achieve a combined frequency above $1000$ waves per second.

Nociceptors

Sensory receptors found predominantly in the skin, muscles, and organs that detect hurtful temperatures, pressure, or chemicals to signal pain.

Gate-Control Theory

The theory that the spinal cord contains a neurological gate that blocks pain signals or allows them to pass to the brain, opened by small nerve fibers and closed by larger fibers or brain-to-spinal-cord signals.

Phantom-Limb Pain

The phenomenon wherein the brain misinterprets and amplifies spontaneous central nervous system activity, producing painful sensations in a nonexistent, amputated limb.

Gustation

The chemical sense of taste, detecting sweet, salty, sour, bitter, umami, and oleogustus molecules via taste receptor cells in taste bud pores.

Oleogustus

A basic taste sensation that indicates the presence of fats used for energy, insulation, and cell growth.

Olfaction

The chemical sense of smell, initiated when airborne odor molecules bind to receptor cells at the top of the nasal cavity.

Olfactory Bulb

The brain structure receiving neural signals directly from olfactory receptor cell axons before sending them onward to the temporal lobe's smell cortex and the limbic system.

Kinesthetic Sense (Kinesthesia)

The system for sensing the position and movement of individual body parts using proprioceptors located in muscles, tendons, and joints.

Vestibular Sense

The sensory system monitoring head position, movement, and balance via fluid-filled semicircular canals and calcium crystal-filled vestibular sacs in the inner ear.

Sensory Interaction

The principle that one sense may influence another, such as when the smell of food dramatically influences its perceived taste.

McGurk Effect

A perceptual phenomenon where visual cues of a speaker forming one syllable blend with conflicting auditory cues of another syllable, causing the brain to perceive a third, distinct sound.

Embodied Cognition

The influence of bodily sensations, gestures, and other physical states on cognitive preferences and judgments.

Synesthesia

A rare neurological condition in which brain circuits for two or more senses become joined, causing stimulation of one sense to involuntarily trigger an experience in another.