Introductory Psychology: History, Biological Bases, Research Methods, and Sensation & Perception

Comprehensive vocabulary flashcards covering the historical development of psychology, neural communication and neuroanatomy, scientific research design and statistics, psychophysics, and the visual, auditory, olfactory, and gustatory systems.

Psychology (Etymological Roots)

Derived from two Greek roots: $psyche$, meaning soul, mind, or spirit, and $logos$, meaning the study of a subject.

Psychology (Scientific Definition)

The scientific discipline that studies behavior and the physiological and cognitive processes that underlie it.

Wilhelm Wundt

The founder of experimental psychology who established the world's first formal laboratory in Leipzig, Germany, in the 1870s and defined psychology as the scientific study of conscious experience.

Structuralism

An early psychological school that aimed to deconstruct conscious experience into its basic foundational elements (sensations, feelings, and images) using trained, rigorous introspection.

Functionalism

An early psychological perspective that investigated the practical purposes and adaptive functions of conscious mental activity, viewing consciousness as a continuous, dynamic stream.

Classical Behaviorism

A school of thought founded by John B. Watson that abandoned internal conscious states to focus exclusively on publicly observable, measurable behavior through stimulus-response ($S\text{-}R$) associations.

Psychoanalysis

A theoretical framework formulated by Sigmund Freud attributing personality, motivation, and psychological disorders to unconscious conflicts, instinctual drives, and repressed childhood experiences.

Radical Behaviorism

An approach led by B. F. Skinner asserting that internal mental events do not direct actions; behavior is governed entirely by external environmental contingencies and operant conditioning.

Humanistic Psychology

A theoretical orientation emphasizing unique human qualities such as conscious free will, personal growth, and self-actualization, rejecting deterministic models of behaviorism and psychoanalysis.

Cognitive Psychology

The scientific study of mental processes involved in acquiring, storing, retrieving, and manipulating knowledge, conceptualizing the mind as an advanced information-processing system.

Evolutionary Psychology

The study of behavioral and cognitive processes through their adaptive value for species survival and reproductive fitness across successive generations based on natural selection principles.

Positive Psychology

A movement refocusing scientific study on adaptive, fulfilling, and purpose-driven facets of human life, organized around positive subjective experiences, positive individual traits, and positive institutions.

Developmental Psychology

A contemporary research area (accounting for $23.4\%$ of research activity) that investigates human behavioral, intellectual, and psychological changes across the entire life span.

Social Psychology

A contemporary research area (accounting for $21.1\%$ of research activity) focusing on interpersonal behavior and how social forces, norms, attitudes, and groups govern actions.

Psychometrics

A specialized research subfield (accounting for $4.8\%$ of research activity) devoted to the psychological measurement of behavior, traits, and abilities through the standardization of tests and statistical analysis techniques.

Clinical Psychology

A major applied professional specialty dedicated to the evaluation, diagnosis, psychological testing, and treatment of moderate to severe psychological disorders and emotional dysfunction.

Industrial and Organizational (I/O) Psychology

An applied specialty applying psychological concepts to corporate and workplace environments, focusing on employee selection, job morale, productivity, and organizational efficiency.

Neuron Anatomy

The structural anatomy of a communication cell consisting of the soma (integrates signals), dendrites (receive inputs), axon (transmits electrical impulses), myelin sheath (insulates axon), and terminal buttons (secrete neurotransmitters).

Types of Neuroglia

Non-neuronal support cells categorized into Central Nervous System glia (ependymal cells, oligodendrocytes, astrocytes, microglia) and Peripheral Nervous System glia (Schwann cells, satellite cells).

Resting Potential

The stable, inactive electrical state of an unexcited neuron hovering around $-70\,mV$, actively maintained by the sodium-potassium pump expelling $3\,Na^+$ ions for every $2\,K^+$ ions imported.

Action Potential

A rapid electrochemical voltage spike triggered when excitation reaches $-55\,mV$, progressing through depolarization ($+30\,mV$), repolarization, and hyperpolarization (< $-70\,mV$).

All-or-None Law

The neurophysiological principle stating that an action potential is either fired completely or not fired at all; stimulus intensity is encoded by firing frequency rather than spike amplitude.

Absolute Refractory Period

The brief mandatory interval following an action potential during which an axon cannot fire another impulse, regardless of stimulus intensity, enforcing unidirectional conduction.

Synapse Structure

A specialized functional junction between neurons comprising the presynaptic terminal button, a synaptic cleft measuring approximately $20\,nm$, and postsynaptic receptor protein sites.

Reuptake

The molecular clearance process wherein released neurotransmitters are reabsorbed across the presynaptic membrane via specialized transporter pumps for repackaging and recycling.

EPSP and IPSP Graded Potentials

Excitatory postsynaptic potentials (EPSPs) depolarize the membrane toward threshold to promote firing, whereas inhibitory postsynaptic potentials (IPSPs) hyperpolarize the membrane to suppress firing.

Acetylcholine (ACh)

A neurotransmitter released by motor neurons controlling skeletal muscles and regulating memory, arousal, and attention; marked deficits in ACh pathways characterize Alzheimer's disease.

Dopamine (DA)

A neurotransmitter regulating voluntary motor movement and medial forebrain bundle reward pathways; deficits cause Parkinsonism, while excessive receptor activity relates to schizophrenic disorders.

Gamma-Aminobutyric Acid (GABA)

The primary widely distributed inhibitory neurotransmitter of the central nervous system that suppresses neuronal excitability to modulate anxiety, sleep, and arousal.

Endorphins

Endogenous neuropeptides chemically resembling opiate drugs that modulate pain relief, stress buffering, and eating regulation in the central nervous system.

Synaptic Pruning

The neurodevelopmental process of eliminating redundant or underactive synapses, reducing synaptic density from an infant peak of $22 \times 10^{11}$ down to roughly $11.5 \times 10^{11}$ by age $70$.

Long-Term Potentiation (LTP)

A long-lasting increase in synaptic transmission efficiency following high-frequency stimulation, driven by elevated neurotransmitter release, dendritic spine expansion, and intracellular influx of $Na^+$ and $Ca^{2+}$.

Neuroplasticity

The brain's structural and functional capacity to reorganize neural circuits and alter physiological operations in response to experiential learning, environmental demands, or neural injury.

Somatic Reflex Arc

A rapid, involuntary circuit where sensory receptors direct signals along afferent neurons to spinal interneurons, directly stimulating efferent motor neurons to produce an immediate muscle contraction.

Autonomic Nervous System Divisions

The autonomic division regulating visceral functions, split into the catabolic sympathetic system ('fight or flight') and the anabolic parasympathetic system ('rest and digest').

Medulla

A vital hindbrain structure adjoining the spinal cord that governs essential unconscious autonomic functions, including heartbeat, blood circulation, respiration, and protective airway reflexes.

Cerebellum

A folded hindbrain structure coordinating smooth voluntary muscular movements, physical balance, and motor execution, as well as participating in language processing and emotional recall.

Thalamus

A bilateral subcortical forebrain relay station that filters, organizes, and routes all incoming sensory signals—except olfaction—to designated areas of the cerebral cortex.

Hypothalamus

A subcortical forebrain structure regulating internal homeostatic balance, autonomic activity, pituitary hormone secretion, and the '4 F's' (Fighting, Fleeing, Feeding, and Fornication).

Hippocampus

A limbic system structure essential for the consolidation of declarative memories, long-term memory formation, and spatial cognitive mapping.

Amygdala

A limbic system module responsible for associative fear learning, defensive emotional responses, and the motivational evaluation of sensory inputs.

Corpus Callosum

A thick transverse bridge of over $200\text{ million}$ axons spanning the longitudinal fissure to convey information between the left and right cerebral hemispheres.

Lobes of the Cerebral Cortex

The four cortical regions: occipital (visual cortex), parietal (somatosensory cortex and spatial processing), temporal (auditory cortex and language comprehension), and frontal (motor and prefrontal executive cortex).

Cortical Homunculus

The inverted anatomical body mapping along the precentral and postcentral gyri, where disproportionate cortical space is allocated based on fine motor control or tactile receptor sensitivity.

Split-Brain Visual Processing

A testing paradigm showing that in commissurotomy patients, left visual field stimuli reach the mute right hemisphere (identifiable only by the left hand), while right visual field stimuli reach the verbal left hemisphere.

Operational Definition

A precise specification of the exact concrete operations, measurement procedures, or behavioral criteria used to quantify an abstract scientific variable.

Independent Variable (IV)

The condition, event, or treatment systematically manipulated by an experimenter to determine its direct causal effect on an outcome.

Dependent Variable (DV)

The outcome variable measured by the researcher, hypothesized to change as a direct causal result of manipulations of the independent variable.

Classical Pre-test / Post-test Design

An experimental framework evaluating causal impact by comparing experimental and control groups at baseline, measuring change post-event, and contrasting post-test outcomes.

Normal Distribution

A symmetrical, bell-shaped frequency distribution where approximately $68\%$ of scores fall within $\pm 1\,SD$ ($\mu \pm 1\sigma$) and roughly $95\%$ fall within $\pm 2\,SD$ ($\mu \pm 2\sigma$) of the mean.

Correlation Coefficient ($r$)

A standardized numerical index ranging from $-1.00$ to $+1.00$ whose sign indicates association direction and whose absolute value indicates association strength, which cannot prove causality.

Twin and Adoption Study Methodology

Behavioral genetics research designs comparing identical twins ($100\%$ shared genes) and fraternal twins ($50\%$ shared genes) raised together or apart to isolate genetic versus environmental influences.

Absolute Threshold

The specific physical intensity level along an S-shaped ogive curve at which an organism can reliably detect an environmental stimulus $50\%$ of the time.

Difference Threshold (JND)

The minimum physical incremental difference in magnitude or intensity required for a sensory modality to perceive that a stimulus change has occurred.

Signal-Detection Matrix

The four-outcome decision model in sensory perception evaluating true presence vs. reporting: Hit, Miss, False Alarm, and Correct Rejection.

Sensory Adaptation

The progressive, automatic reduction in sensory receptor sensitivity that occurs in the prolonged presence of continuous, unchanging, and repetitive stimulation.

Physical Properties of Light

The physical characteristics of visible electromagnetic waves ($400\,nm$ to $700\,nm$) and their psychological correlates: amplitude (brightness), wavelength (hue), and purity (saturation).

Fovea

A tiny depression in the center of the retina packed exclusively with cone photoreceptors, providing the point of maximal visual acuity and spatial detail.

Optic Disk

The circular exit point on the retina where ganglion cell axons assemble to form the optic nerve; devoid of photoreceptors, creating the physiological blind spot.

Rods vs. Cones

Cones are daylight, high-acuity color photoreceptors densely situated in the fovea; rods are dim-light, highly sensitive peripheral photoreceptors specialized for night vision and motion tracking.

Additive vs. Subtractive Colour Mixing

Additive mixing superimposes radiant light wavelengths to add total energy (red, green, and blue form white); subtractive mixing combines pigments that absorb wavelengths, leaving less reflected light.

Opponent Process Circuitry

A color vision mechanism where cones wire into ganglion cells exhibiting antagonistic excitation and inhibition along red vs. green, yellow vs. blue, and black vs. white channels, explaining afterimages.

Physical Properties of Sound

The acoustic waveform characteristics: amplitude (loudness in decibels, $dB$), frequency (pitch in hertz, spanning $20\,Hz$ to $20,000\,Hz$), and purity (timbre).

Human Ear Anatomy

The anatomical hearing mechanism comprising the external ear (pinna, auditory canal), middle ear (tympanic membrane, hammer, anvil, stirrup), and inner ear (cochlea, basilar membrane).

Basilar Membrane

A fluid-bathed structure running inside the cochlea lined with auditory hair cells whose stereocilia shear during pressure oscillations to trigger action potentials along the auditory nerve.

Place Theory vs. Frequency Theory

Place theory posits pitch reflects the location of maximal vibration along the basilar membrane (high frequencies > $1,000\,Hz$); frequency theory posits pitch reflects whole-membrane firing rates (< $1,000\,Hz$).

Auditory Localization

The ability to determine sound origin in 3D space utilizing binaural cues: interaural timing differences and interaural intensity differences caused by the acoustic sound shadow of the head.

Perceptual Set

A cognitive readiness or mental predisposition to interpret sensory input in a specific manner based on expectations, context, prior knowledge, or cultural conditioning.

Inattentional Blindness

The failure to perceive an unexpected, fully visible object or event in the visual field because central attentional resources are concentrated on a competing task.

Bottom-Up vs. Top-Down Processing

Bottom-up processing constructs perception upward from basic sensory feature detectors; top-down processing begins conceptually with hypotheses and prior knowledge to guide feature inspection.

Gestalt Psychology

A theoretical school asserting that conscious visual perception is qualitatively different from and greater than the simple sum of individual sensory components.

Distal vs. Proximal Stimuli

A distal stimulus is an actual physical object in external space, whereas a proximal stimulus is the changing pattern of physical energy directly stimulating sensory receptors.

Perceptual Constancy

The cognitive tendency to perceive familiar objects as retaining invariant size, shape, and color despite drastic physical distortions in the proximal retinal image.

Retinal Disparity

A binocular depth cue arising from horizontal eye separation, where closer physical objects project larger coordinate differences between the left and right retinas.

Pictorial Depth Cues

Monocular distance cues present in 2D images, including linear perspective, texture gradient, interposition (overlap), relative size, height in plane, and light and shadow.

Ames Room Illusion

A trapezoidal optical illusion with non-parallel walls and slanted floors that exploits assumptions of rectangularity to distort size constancy, making identical individuals appear giant or tiny.

Olfactory Anatomy

The smell transduction apparatus where airborne chemical odorants bind to olfactory cilia, sending signals through the cribriform plate to the olfactory bulb and directly to cortex, bypassing the thalamus.

Gustatory Anatomy

The tongue's sensory surface where trenches around fungiform, foliate, and circumvallate papillae contain taste buds that detect sweet, sour, bitter, salty, and umami tastes.

Flavour

A multisensory cognitive perception synthesized by the central nervous system, combining primary taste qualities, retronasal olfaction, oral somatosensation (texture and temperature), and top-down visual cues.