Foundational Concepts in Psychology: Science, Methods, and Brain

Posted on Mar 9, 2026 in Psychology

Chapter 1: Psychology Science Fundamentals

Defining Psychology and Historical Views

Psychological Science is the scientific study of the Mind (internal/hidden) and Behavior (external/observable).

Historical Shifts in Demographics

  • Historically white male dominated.
  • Currently, about 70% of PhDs are women, and 30% are People of Color (POC).

Philosophical Foundations

  • Dualism (Descartes): Mind and Body are fundamentally different; connected at the pineal gland; non-falsifiable.
  • Materialism (Hobbes): “Mind is what brain does”; supported by fMRI and lesion studies.
  • Realism (Locke): Perception is a direct photocopy of reality.
  • Idealism (Kant): Perception is an active interpretation; supported by the eyelid test (pressure perceived as light).
  • Empiricism (Locke): Knowledge comes from experience; the mind is a tabula rasa (blank slate).
  • Nativism (Kant): Some knowledge is innate (e.g., grammar structures).

Major Schools of Thought

  • Structuralism (Wundt): Attempted to isolate “atoms of the mind” via introspection (ultimately failed due to subjectivity).
  • Functionalism (James): Focused on the adaptive significance of mental processes (Darwinian “why”).
  • Psychoanalysis (Freud): Emphasized unconscious urges; largely non-falsifiable.
  • Behaviorism (Watson/Skinner): Studied only observable behavior. Pavlov (Classical conditioning: involuntary); Skinner (Operant conditioning: reinforcement/voluntary).
  • Gestalt (Wertheimer): Emphasized that the “Whole is greater than the sum of its parts”; context matters.
  • Cognitive Revolution (Chomsky): Conceptualized the mind as a computer/information processor; noted predictable grammar errors in children.

Modern Trends

Current research focuses on:

  • Cognitive Neuroscience: Studying the human brain in cognitive tasks.
  • Behavioral Neuroscience: Studying animal models.
  • Cultural Psychology: How values shape the mind.

Chapter 2: Research Methods in Psychology

The Scientific Approach

Empiricism: Knowledge acquisition through systematic observation.

Theory-Data Cycle: Theory $\rightarrow$ Hypothesis (must be falsifiable) $\rightarrow$ Data Collection.

Challenges in Human Research

Humans are unique because they are:

  1. Complex: Approximately 100 billion neurons.
  2. Variable: High individual differences.
  3. Reactive: Participants change behavior when observed.

Measurement Concepts

Operational Definition: A measurable description of a construct.

Good measures require:

  • Construct Validity: Accuracy in measuring the intended concept.
  • Power: Sensitivity to detect a true effect.
  • Reliability: Consistency of results over time or across measures.

Controlling Bias

  • Demand Characteristics: Participants act as they think expected. Solutions: naturalistic observation, implicit measures (e.g., pupil dilation), or anonymity.
  • Observer Bias: Researcher sees what they expect (e.g., Maze-bright rats). Solution: double-blind procedures.

Correlation and Causation

Correlation ($r$): Measures how two variables move together (range: -1 to +1); does not imply causation.

Third-Variable Problem: An unmeasured factor causes both correlated variables (e.g., heat causes both ice cream sales and murders).

Experimental Design

Experiments establish causality through:

  • Manipulation: Changing the Independent Variable (IV).
  • Random Assignment: Ensures groups are equivalent at the start, supporting Internal Validity (causality).
  • Dependent Variable (DV): The measured outcome.

Statistical Significance and Generalizability

$P < .05$: The result is statistically significant (less than a 5% chance it occurred randomly).

External Validity: The degree to which results generalize to the real world.

Sampling: Random Sampling ensures a representative sample.

WEIRD Samples: Many studies use samples that are White, Educated, Industrialized, Rich, and Democratic, limiting external validity.

Survivorship Bias: Ignoring data from failures or non-survivors (e.g., analyzing only bullet holes on returning planes).

Ethics in Research

The Belmont Report established core ethical principles:

  1. Respect for Persons: Informed consent required.
  2. Beneficence: Minimal risk to participants.
  3. Justice: Fair distribution of benefits and burdens.

The IRB (Institutional Review Board) enforces these ethics. Open Science practices, like pre-registration, aim to increase transparency.

Chapter 3: Neuroscience and the Brain

The Neuron

The basic cell of the nervous system:

  • Cell Body (Soma): Maintains cell life.
  • Dendrites: Receive incoming signals.
  • Axon: Transmits signals away.
  • Synapse: The gap between neurons.

Myelin Sheath: Insulates the axon, speeding transmission; deterioration causes diseases like MS.

Neuron Types

  • Sensory Neurons: Carry signals to the Central Nervous System (CNS).
  • Motor Neurons: Carry signals from the CNS to muscles.
  • Interneurons: Most common; connect neurons within the CNS.

Action Potential (Electrical Signal)

An all-or-none electrical spike, typically reaching +40mV.

  1. Resting State (-70mV): High $\text{Na}^+$ outside, high $\text{K}^+$ inside.
  2. Threshold: Reached at the axon hillock.
  3. Depolarization: $\text{Na}^+$ rushes in.
  4. Repolarization: $\text{K}^+$ rushes out.
  5. Refractory Period: Prevents signals from traveling backward.

Synaptic Transmission (Chemical Signal)

Vesicles release Neurotransmitters (NTs) into the synapse, binding to receptors (lock-and-key mechanism).

NT removal occurs via reuptake, enzyme deactivation, or diffusion.

Key Neurotransmitters

  • ACh (Acetylcholine): Muscles and learning; low levels linked to Alzheimer’s.
  • Dopamine: Pleasure, motor control; high levels linked to Schizophrenia, low levels to Parkinson’s.
  • Glutamate: Primary excitatory NT.
  • GABA: Primary inhibitory NT.
  • Serotonin: Mood and sleep regulation.
  • Endorphins: Natural pain relief.

Drugs: Agonists increase NT action; Antagonists decrease NT action.

Nervous System Organization

  • CNS: Brain and Spinal Cord.
  • PNS: Somatic (voluntary) and Autonomic (involuntary).

Autonomic Subdivisions:

  • Sympathetic: Arousing (“Fight or Flight”); dilates pupils, increases heart rate.
  • Parasympathetic: Calming (“Rest and Digest”); slows heart rate, increases digestion.

Spinal Reflex: A fast signal (Reflex Arc) that bypasses the brain for immediate reaction.

Brain Structures

Hindbrain

  • Medulla: Controls vital functions (heart rate, breathing).
  • Cerebellum: Coordinates fine motor control and balance.

Midbrain

  • Tectum/Tegmentum: Involved in orientation to stimuli.

Forebrain

  • Thalamus: Major sensory relay station (except smell).
  • Hypothalamus: Regulates the 4 F’s: Feeding, Feeling temperature, Fighting, and Female/Male sexual behavior.
  • Hippocampus: Crucial for forming new explicit memories.
  • Amygdala: Processes emotion, especially fear.

Cerebral Cortex

Divided into hemispheres with contralateral control (left controls right side, etc.), connected by the Corpus Callosum.

  • Occipital Lobe: Vision.
  • Temporal Lobe: Auditory processing, meaning, and language comprehension (Wernicke’s Area).
  • Parietal Lobe: Touch and spatial awareness; contains the Somatosensory Cortex (Homunculus).
  • Frontal Lobe: Planning, decision-making, and voluntary movement (Motor Cortex); language production (Broca’s Area).

Plasticity and Methods

Plasticity: The brain’s ability to adapt; neighboring neurons can take over functions (e.g., in Phantom Limb syndrome).

Research Methods:

  • Lesions: Studying damage (e.g., Phineas Gage and personality change).
  • EEG: Measures electrical brain waves.
  • CT/MRI: Measures brain structure.
  • PET/fMRI: Measures brain function via metabolic activity or blood flow.

Chapter 4: Sensation and Perception (Vision Focus)

Core Concepts

  • Sensation: Physical stimulation of sensory organs.
  • Perception: Interpretation and meaning assigned to that stimulation.
  • Transduction: Converting physical energy into neural signals.
  • Adaptation: Decline in responsiveness to an unchanging stimulus (e.g., the smell of bacon fading).

Thresholds

  • Absolute Threshold: The minimum intensity needed for detection 50% of the time.
  • Just Noticeable Difference (JND): The minimal detectable change between stimuli.
  • Weber’s Law: The JND is a constant proportion of the original stimulus intensity.

Signal Detection Theory

Distinguishes between true sensitivity and the observer’s Criterion (bias):

  • Liberal Criterion: High rate of false alarms.
  • Conservative Criterion: High rate of misses.

Vision

Physical properties of light relate to visual experience:

  • Wavelength (Length): Determines Hue (color).
  • Amplitude: Determines Brightness.
  • Purity: Determines Saturation (color intensity).

Visual Anatomy

Light passes through the Cornea $\rightarrow$ Pupil $\rightarrow$ Lens (which adjusts via Accommodation to focus on the retina).

The Retina

  • Rods: Function in low light (scotopic vision); responsible for peripheral vision and seeing in gray.
  • Cones: Function in daylight (photopic vision); responsible for color and detail, concentrated in the fovea.

Humans have three cone types: S-Blue, M-Green, and L-Red. Fatiguing one cone type leads to color afterimages.

Visual Processing Streams

Signals travel from the retina $\rightarrow$ Thalamus $\rightarrow$ Area V1 (detects edges).

  • Dorsal Stream: “Where/How” pathway, projecting to the Parietal Lobe (location/action).
  • Ventral Stream: “What” pathway, projecting to the Temporal Lobe (object identity).

Binding Problem: How the brain combines separate features (color, shape, motion) into a unified object, often requiring attention (failure leads to illusory conjunctions).

Gestalt Principles of Organization

The brain organizes sensory input based on simplicity:

  • Closure
  • Continuity
  • Similarity
  • Proximity
  • Common Fate

Perceptual Failures

  • Inattentional Blindness: Failing to see an obvious object because attention is directed elsewhere (e.g., missing the gorilla).
  • Change Blindness: Failing to notice changes in the visual environment.

Chapter 6: Memory

Memory Processes

Memory is constructed, not recorded.

  • Encoding: Getting information into the brain.
  • Storage: Maintaining information over time.
  • Retrieval: Recalling stored information.

Encoding Strategies

  • Semantic Encoding: Focusing on meaning (most effective; involves frontal lobe areas).
  • Visual Imagery Encoding: Creating mental pictures (involves occipital lobe).
  • Organizational Encoding: Categorizing information (involves frontal lobe).

Information related to survival is remembered best.

Storage Stages

  • Sensory Memory: Very brief storage. Iconic (<1 second, visual); Echoic (~5 seconds, auditory).
  • Short-Term Memory (STM): Capacity of 5-7 items, lasts 15-20 seconds; extended via rehearsal or chunking.
  • Working Memory: Active maintenance system, involving the Visuospatial Sketchpad, Phonological Loop, Episodic Buffer, and Central Executive.
  • Long-Term Memory (LTM): Unlimited capacity.

Consolidation

The process stabilizing memories, largely occurring during sleep. The Hippocampus consolidates new explicit memories.

LTP (Long-Term Potentiation): The cellular mechanism: “Cells that fire together, wire together.” Patient HM demonstrated anterograde amnesia (inability to form new facts) but could still learn skills (implicit memory).

Retrieval

Cues aid recall. Effectiveness depends on matching the context of learning:

  • Encoding Specificity: Matching the context (e.g., studying underwater and being tested underwater).
  • State-Dependent Memory: Matching mood or physiological state.

Testing Effect: Retrieval practice is superior to simple restudying.

Reconsolidation: Retrieval makes a memory temporarily vulnerable to modification or distortion (e.g., Brian Williams’ altered accounts).

Types of Long-Term Memory

  • Implicit (Unconscious): Procedural memory (skills, which bypasses the hippocampus) and Priming (faster processing due to prior exposure).
  • Explicit (Conscious): Semantic memory (facts) and Episodic memory (personal experiences).

Memory Failures (The 7 Sins)

  1. Transience: Forgetting over time, often due to interference.
  2. Absentmindedness: Lapses in attention during encoding or retrieval.
  3. Blocking: Temporary inability to access information (“tip of the tongue”).
  4. Misattribution: Assigning a memory to the wrong source (e.g., eyewitness error).
  5. Suggestibility: False memories implanted by leading questions.
  6. Bias: Current knowledge distorts memory of the past.
  7. Persistence: Inability to forget unwanted memories (often emotional memories linked to the amygdala).