MCAT P/S: Foundational Concept 6: Perception, Cognition, Consciousness, Emotion

Sensation

The process by which sensory receptors and nervous system receive stimulus energies from the environment

Perception

The process of organizing and interpreting sensory information to recognize meaningful objects/events

Absolute threshold

The minimum stimulus intensity required to detect a stimulus 50% of the time

Difference threshold (JND)

The minimum difference in stimulus intensity needed to perceive a change

Weber's Law

The JND is proportional to the magnitude of the original stimulus

Signal detection theory

The idea that perception depends on both stimulus intensity and psychological state (expectations, motivation)

Sensory adaptation

Decreased sensitivity to a constant stimulus over time

Psychophysics

The study of relationships between physical stimuli and psychological perception

Bottom-up processing

Data-driven processing based on sensory input

Top-down processing

Concept-driven processing based on expectations and prior knowledge

Sensory receptors

Specialized cells that detect environmental stimuli and convert them into neural signals

Mechanoreceptors

Receptors that respond to mechanical pressure (touch, hearing)

Photoreceptors

Receptors that respond to light (rods and cones)

Chemoreceptors

Receptors that detect chemical stimuli (taste, smell)

Thermoreceptors

Receptors that detect temperature

Nociceptors

Receptors that detect pain

Structure of the eye

Includes cornea, lens, retina, fovea; focuses light onto retina

Rods

Photoreceptors for low light and peripheral vision (black/white)

Cones

Photoreceptors for color vision and visual acuity

Fovea

Central region of retina with highest concentration of cones

Optic nerve

Carries visual information from retina to brain

Feature detection

Ability of neurons to respond to specific features (edges, motion)

Parallel processing

Simultaneous processing of multiple aspects of a stimulus (color, motion, form)

Structure of the ear

Outer, middle, inner ear; transmits sound waves to cochlea

Cochlea

Fluid-filled structure where hair cells transduce sound waves

Hair cells

Mechanoreceptors that convert vibrations into neural signals

Pitch perception

Determined by frequency of sound waves

Somatosensation

Sense of touch including pressure, pain, temperature

Kinesthetic sense

Awareness of body position and movement

Vestibular sense

Sense of balance and spatial orientation

Olfaction

Sense of smell via olfactory receptors

Pheromones

Chemical signals released by organisms affecting behavior of others

Gustation

Sense of taste (sweet, sour, salty, bitter, umami)

Gestalt principles

Rules describing how we organize sensory input into meaningful wholes

Closure

Tendency to perceive incomplete figures as complete

Proximity

Objects close together are grouped together

Similarity

Similar objects are grouped together

Continuity

Preference for continuous patterns

Figure-ground

Distinguishing object from background

Depth perception

Ability to perceive distance (binocular & monocular cues)

Perceptual constancy

Perceiving objects as stable despite changes in sensory input

Selective attention

Focusing conscious awareness on one stimulus

Divided attention

Attending to multiple stimuli simultaneously

Information-processing model

Mind processes information like a computer (input → storage → output)

Piaget's stages of cognitive development

Sensorimotor, preoperational, concrete operational, formal operational

Sensorimotor stage (0-2)

Object permanence develops

Preoperational stage (2-7)

Symbolic thinking, egocentrism

Concrete operational stage (7-11)

Logical thinking about concrete objects

Formal operational stage (12+)

Abstract reasoning

Heuristic

Mental shortcut used to make decisions quickly

Availability heuristic

Judging likelihood based on ease of recall

Representativeness heuristic

Judging based on similarity to prototype

Overconfidence bias

Overestimating accuracy of one's beliefs

Belief perseverance

Maintaining beliefs despite contradictory evidence

Intelligence

The ability to learn, understand, and adapt

Fluid intelligence

Problem-solving and reasoning ability

Crystallized intelligence

Accumulated knowledge and experience

Consciousness

Awareness of self and environment

Circadian rhythm

Biological clock regulating sleep-wake cycle (~24 hr)

Sleep stages

NREM stages 1-3 and REM sleep

REM sleep

Stage associated with dreaming and brain activity

Sleep disorders

Insomnia, narcolepsy, sleep apnea

Psychoactive drugs

Substances that alter consciousness

Depressants

Reduce neural activity (alcohol, benzodiazepines)

Stimulants

Increase neural activity (caffeine, cocaine)

Hallucinogens

Alter perception (LSD)

Encoding

Process of getting information into memory

Storage

Maintaining information over time

Retrieval

Accessing stored information

Sensory memory

Brief storage of sensory information

Working memory

Short-term manipulation of information

Long-term memory

Relatively permanent storage

Explicit memory

Conscious recall (facts, events)

Implicit memory

Unconscious memory (skills, habits)

Semantic memory

Facts and general knowledge

Episodic memory

Personal experiences

Recall

Retrieving information without cues

Recognition

Identifying previously learned information

Decay

The fading of memory over time

Interference

Disruption of memory by other information

Proactive interference

Old info interferes with new

Retroactive interference

New info interferes with old

Alzheimer's disease

Neurodegenerative disease causing memory loss

Korsakoff's syndrome

Memory disorder due to thiamine deficiency

Neuroplasticity

Brain's ability to reorganize and form new connections

Long-term potentiation

Strengthening of synapses with repeated use

Language

System of communication using symbols

Phonemes

Basic sound units

Morphemes

Smallest meaningful units

Syntax

Rules for sentence structure

Broca's area

Speech production (damage → nonfluent aphasia)

Wernicke's area

Language comprehension (damage → fluent aphasia)

Nativist theory

Language ability is innate

Learning theory

Language acquired through reinforcement

Interactionist theory

Language develops through interaction

Emotion

A complex response involving physiological, cognitive, and behavioral components

Universal emotions

Happiness, sadness, anger, fear, surprise, disgust

James-Lange theory

Emotion = physiological response first, then interpretation

Cannon-Bard theory

Emotion and physiological response occur simultaneously

Schachter-Singer theory

Emotion = arousal + cognitive label