MCAT Psych/Soc Processing the Environment and Sensory Perception

Comprehensive vocabulary flashcards covering sensory perception, anatomy of the eye and ear, states of consciousness, drug dependence, memory, cognition, emotion, and stress management.

Retinal disparity

A binocular depth cue based on the fact that since human eyes are approximately $2.5\,inches$ apart, they receive slightly different views of objects.

Convergence

A binocular depth cue based on the degree to which the eyeballs turn inward to focus on an object; muscles are relaxed for far objects and contracted for close objects.

Relative height

A monocular cue where objects that are higher in the field of view are perceived to be farther away.

Motion parallax

Also known as 'relative motion', this monocular cue describes how objects farther away appear to move slower while closer objects appear to move faster.

Size Constancy

The perception that an object remains the same size even if the image it casts on the retina becomes larger or smaller as it moves closer or further away.

Sensory Adaptation

A process where sensory receptors lose sensitivity to constant stimuli over time, such as the inner ear muscle contracting to dampen vibrations from loud noises.

Just noticeable difference (JND)

The minimum threshold at which an individual can detect a change in a sensation $50\%$ of the time.

Weber’s Law

A principle stating that the ratio of the increment threshold to the background intensity is constant, expressed as $\frac{\Delta I}{I} = k$.

Absolute threshold of sensation

The minimum intensity of a stimulus required to detect it $50\%$ of the time, influenced by factors like expectations, experience, and alertness.

Endolymph

The fluid contained within the semicircular canals that shifts during rotation, allowing the vestibular system to detect head movement and strength of rotation.

Otolithic organs

Structures in the inner ear, including the utricle and saccule, that use $CaCO_3$ crystals on hair cells to detect linear acceleration and head positioning.

Signal Detection Theory

A model of decision making under uncertainty that discerns between important stimuli and 'noise', resulting in outcomes like hits, misses, false alarms, and correct rejections.

d' (Discriminability)

A variable in signal detection theory representing the distance between the means of signal and noise distributions; a smaller value indicates higher task difficulty.

Bottom-up processing

Data-driven processing that begins with the stimulus and uses inductive reasoning to influence perception without preconceived cognitive constructs.

Law of Pragnanz

A Gestalt principle stating that reality is reduced to the simplest form possible by the brain, such as perceiving the Olympic rings as five circles.

Conjunctiva

A thin layer of epithelial cells lining the inside of the eyelids that protects and moisturizes the cornea.

Fovea

A special part of the macula in the retina that is completely covered in cones and lacks rods, allowing for high-resolution vision.

Choroid

A network of blood vessels behind the retina, pigmented black in humans, which serves to nourish the retina.

Phototransduction cascade

The set of molecular events in a rod that causes it to turn off when hit by light, involving rhodopsin, transducin, and phosphodiesterase (PDE).

Trichromatic theory of vision

The theory that the eye contains three types of cones sensitive to specific colors: red ($60\%$), green ($30\%$), and blue ($10\%$).

Parvocellular pathway

A visual pathway specialized for detecting form and high spatial resolution in stationary objects, providing information about color and boundaries.

Magnocellular pathway

A visual pathway specialized for detecting motion with high temporal resolution, but which lacks color and high spatial resolution.

Organ of Corti

A membrane in the cochlea comprised of the basilar and tectorial membranes that converts fluid movement into electrical impulses via hair cells.

Basilar tuning

The mechanism where different frequencies stimulate different parts of the basilar membrane; base hair cells respond to high frequencies and apex hair cells to low frequencies.

TrypV1 receptor

A protein receptor in the cell membrane sensitive to both temperature and pain, also activated by molecules like capsaicin.

Gate control theory of pain

A psychological theory stating that non-painful input can suppress pain sensation by closing 'gates' in the central nervous system, often summarized as 'fast blocks slow'.

Glomerulus

A specific location in the olfactory bulb where all olfactory sensory cells sensitive to a particular molecule synapse.

Pheromones

Chemical signals produced by one member of a species that induce an innate response in a conspecific, often used for mating or territory marking.

Labelled lines theory of gustation

States that each of the five receptor cell types in a taste bud has a dedicated axon that sends separate taste information to specific parts of the gustatory cortex.

Beta waves

Brain waves oscillating at $12-30\,Hz$ associated with alertness and concentration.

Sleep spindles

Bursts of rapid brain activity occurring in N2 sleep that may help inhibit certain perceptions to maintain a tranquil sleep state.

Manifest content

According to Freud, the literal meaning or events that happen within a dream, such as being chased by a monster.

Activation Synthesis Hypothesis

The theory that dreams result from the frontal cortex trying to interpret and synthesize random electrical impulses produced by the brainstem during REM sleep.

Benzodiazepines

A class of depressants that enhance the brain's response to GABA by opening GABA-activated chloride channels, used to treat insomnia and anxiety.

Opiates

Natural substances like morphine and codeine that act on endorphin receptors to reduce pain (analgesia) and induce euphoria.

Ventral tegmental area (VTA)

The region of the midbrain that releases dopamine as part of the reward pathway in response to happiness or rewarding experiences.

Anhedonia

A major symptom of depression characterized by the inability to feel pleasure.

Inattentional blindness

The inability to recognize an unexpected object or stimulus in plain sight when attention is directed elsewhere.

Dual coding hypothesis

The theory that it is easier to remember information associated with both words and images than either alone.

Explicit Memory

A category of long-term memory consisting of facts (semantic) and events (episodic) that can be consciously described.

Long-term potentiation (LTP)

The process by which connection strengths between neurons increase with repeated stimulation, serving as a mechanism for learning and memory.

Korsakoff’s Syndrome

A non-progressive form of dementia caused by a deficiency in vitamin B1 (thiamine), often associated with chronic alcoholism and characterized by severe memory loss.

Object permanence

An awareness developed in Piaget's sensorimotor stage ($0-2\,years$) that objects continue to exist even when they cannot be seen.

Cognitive dissonance

The discomfort felt when holding conflicting cognitions, often resolved by changing behavior or modifying, trivializing, or denying thoughts.

Language acquisition device (LAD)

A theoretical brain mechanism proposed by Chomsky that is pre-programmed with a universal grammar and active during the critical period for language learning.

Broca’s aphasia

A communication disorder resulting from damage to the frontal lobe, characterized by broken or halting speech while comprehension remains intact.

Sapir-Whorfian hypothesis

Also known as strong linguistic determinism, this theory asserts that language and linguistic structure completely determine an individual's cognition and perception.

Phoneme

The smallest unit of sound in a language; for example, the English language contains approximately $40$ individual sounds.

James-Lange theory

The theory of emotion stating that physiological responses occur first and the experience of emotion results from interpreting those physical changes.

General Adaptation Syndrome (GAS)

Hans Selye's model of the stress response consisting of three phases: alarm, resistance, and exhaustion.