Unit 1: Biological Bases for Behavior: Topic 6: Sensation

Sensation

the bottom-up process by which your sensory receptors and nervous system receive and detect raw physical or chemical energy from the environment (such as light waves, sound waves, or odor molecules) and convert it into neural signal

Transduction

the process where sensory receptors convert physical or chemical energy from the environment into neural impulses (electrical/action potentials) that the brain can understand and process

Absolute Threshold

the minimum intensity of a physical stimulus that a person can detect 50% of the time.

Just-noticeable difference

also called the difference threshold or difference limen, is the minimum difference in stimulation required for a person to detect that a change has occurred 50% of the time

Sensory Adaptation

the diminished sensitivity to a constant, unchanging stimulus after continued exposure

Weber’s law

the just-noticeable difference (JND) between two stimuli is a constant proportion of the original stimulus intensity.

Synesthesia

a neurological condition where the stimulation of one sensory or cognitive pathway automatically and involuntarily triggers an experience in a second, unrelated sense

Retina

the light-sensitive inner surface at the back of the eyeball that contains photoreceptor cells (rods and cones) and layers of neurons which perform visual transduction—turning light energy into neural signals

Blind spot

the point on the retina where the optic nerve leaves the eye. Because this area contains no photoreceptor cells (no rods or cones), it cannot process light, creating a small gap in the visual field.

Visual/optic nerve

the bundle of nerve fibers that carries neural impulses from the eye's retina to the brain for processing

Lens

the transparent, flexible structure behind the pupil that changes shape to focus incoming light rays onto the retina.

Accomodation

Jean Piaget's theory of cognitive development links mental growth directly to biological maturation and sensory interaction with the environment, dividing development into four stages: sensorimotor (birth–2 years), preoperational (2–7 years), concrete operational (7–11 years), and formal operational (11+ years)

Nearsightedness

a vision condition where you see nearby objects clearly, but distant objects appear blurry

Farsightedness

is a visual condition in AP Psychology where distant objects are seen clearly, but close-up objects appear blurry

Rods

photoreceptor cells in the retina that detect black, white, and gray, and are essential for night and peripheral vision.

Cones

photoreceptor cells in the retina that detect color and fine detail in well-lit conditions

Trichromatic theory

that the human retina contains three types of cone photoreceptors that are each sensitive to different wavelengths of light: short (blue), medium (green), and long (red)

Opponent-process theory

• Color perception is controlled by three opposing pairs of receptor/ganglion cells. When one color in a pair is stimulated, its opposing partner is inhibited.

• The Three Opposing Pairs:

  • Red vs. Green

  • Blue vs. Yellow

  • Black vs. White

Afterimages

a visual sensation that continues to appear in your vision even after the original stimulus has been removed

Dichromatism

a type of color vision deficiency in AP Psychology where a person possesses only two out of the three types of functioning cone photoreceptors in the retina (one cone type is missing or faulty).

Monochromatism

is a rare form of color vision deficiency (color blindness) in AP Psychology where a person can only perceive the world in shades of black, white, and gray (or a single color tone) because they possess only one type of functioning cone photoreceptor or no functioning cones at all.

Prosopagnosia

is a neurological disorder where a person cannot recognize familiar faces—including friends, family, or even themselves—despite having normal vision and memory. In AP Psychology, it is studied as a type of agnosia caused by damage or abnormal development in the brain's visual processing pathway.

Blindsight

a neurological condition where a person with damage to the primary visual cortex in the occipital lobe reports being completely blind, yet can still unconsciously detect, locate, or respond to visual stimuli.

Pitch

our brain's interpretation of a sound wave's frequency (measured in Hertz, or cycles per second)

Loudness

your psychological perception of the intensity or strength of a sound (ranging from soft to loud)

Place theory

that pitch perception depends on where the basilar membrane inside the cochlea is stimulated by sound waves

Volley theory

concept that explains how we perceive mid-range pitches by having groups of auditory nerve fibers fire neural impulses in rapid, alternating succession

Frequency theory

states that we perceive pitch based on the rate at which nerve impulses travel up the auditory nerve.

Sound localization

the auditory system's ability to identify where a sound is coming from in your environment

Conduction impairment

is hearing loss caused by damage to the mechanical system that conducts sound waves to the cochlea

Sensorineural impairment

is hearing impairment caused by damage to the hair cells (cilia) in the cochlea or to the auditory nerve.

Olfactory system

responsible for the sense of smell (olfaction) and is unique among the senses because its neural pathway bypasses the thalamus

Pheromones

chemical substances released into the environment by an animal that trigger a behavioral or physiological response in other members of the same species.

Gustation

is the chemical sense of taste. In AP Psychology, it is studied under Sensation and Perception alongside its sister chemical sense, olfaction (smell). Sweet, Salty, Sour, Bitter, Umami, and Oleogustus

Supertasters

individuals whose sense of taste and oral sensation are significantly more intense than the average person's, an anatomical trait first coined in the 1990s by experimental psychologist Linda Bartoshuk.

Medium

a person who has an average number of taste receptors on their tongue and experiences a balanced, moderate level of taste sensitivity

Nontasters

a person who has fewer taste receptors (taste buds) on their tongue, making them less sensitive to certain tastes—especially bitterness—so foods taste milder or blander to them.

Sensory interaction

the principle that one sense can influence, affect, or combine with another sense to create our overall perception of the environment. Instead of operating in complete isolation, our different sensory systems work together cooperatively.

Gate control theory

the spinal cord contains a neurological "gate" that either blocks pain signals or lets them pass on to the brain.

Phantom limb

the vivid perception and sensation that an amputated or missing body part is still present,

Vestibular sense

is your body's sense of balance, spatial orientation, and gravitational pull. In AP Psychology, it is the sensory system that lets you know if you are upright, tilting, spinning, or accelerating The semicircular canals are three fluid-filled, interconnected loops located in the inner ear (next to the cochlea). Each canal is oriented in a different perpendicular plane to detect rotational (angular) head movement. When you turn or tilt your head, the fluid (endolymph) inside the canals moves and lags behind your physical motion. This moving fluid bends tiny sensory hair cells (located in a swollen area called the ampulla). Bending these hair cells triggers a neural impulse sent via the vestibular nerve to the brain (specifically the cerebellum).

Kinesthesis

the body's system for sensing the position, tension, and movement of individual body parts.