Foundations of Psychological Science: Methods, Biological Bases, and Sensation & Perception

Introducing Psychological Science

🧠 NEURONS & ACTION POTENTIALS (PSYCH 1)

🧠 NEURONS

What is a neuron?

A specialized cell that receives, processes, and transmits information through electrical and chemical signals.

Parts of a Neuron (YOU MUST KNOW THESE)

Dendrites

• Receive incoming signals from other neurons

• Act like antennas

Cell Body (Soma)

• Contains the nucleus

• Integrates incoming signals

Axon

• Long fiber that carries the electrical signal away from the cell body

Myelin Sheath

• Fatty coating around the axon

• Speeds up signal transmission

Axon Terminals

• End of the neuron

• Release neurotransmitters

Synapse

• Gap between neurons where chemical communication occurs

🧪 TYPES OF NEURONS

Sensory Neurons

Carry information from senses to the brain

Motor Neurons

Carry commands from brain to muscles/glands

Interneurons

Connect neurons within the brain and spinal cord

Exam tip: Most neurons in the brain are interneurons.

⚡ ACTION POTENTIALS

What is an action potential?

A brief electrical impulse that travels down the axon of a neuron.

👉 This is how neurons communicate.

RESTING POTENTIAL

• Neuron is not firing

• Inside of neuron is negative relative to outside

• About –70 mV

Why? Unequal distribution of ions (Na⁺ and K⁺)

STEPS OF AN ACTION POTENTIAL (HIGH-YIELD)

1️⃣ Threshold

• Incoming signals must reach a minimum level

• If threshold is reached → neuron fires

• If not → nothing happens

Exam rule: 👉 All-or-none principle Action potentials either happen fully or not at all

2️⃣ Depolarization

• Sodium (Na⁺) channels open

• Na⁺ rushes into the neuron

• Inside becomes positive

3️⃣ Repolarization

• Potassium (K⁺) channels open

• K⁺ flows out of the neuron

• Inside becomes negative again

4️⃣ Hyperpolarization

• Neuron briefly becomes more negative than resting

• Prevents immediate refiring

5️⃣ Refractory Period

• Neuron cannot fire again immediately

• Ensures signals travel one direction

⚡ SIGNAL SPEED

• Myelinated axons transmit signals faster

• Larger axon diameter = faster transmission

Exam trap: More neurotransmitter ≠ faster action potential Speed depends on myelin and axon size

🧠 FROM ELECTRICAL → CHEMICAL

1. Action potential reaches axon terminal

2. Neurotransmitters are released

3. They cross the synapse

4. Bind to receptors on the next neuron

👉 Electrical → chemical → electrical

The Scientific Method in Psychology

The scientific method is a systematic approach used in psychology to investigate phenomena, acquire new knowledge, or correct and integrate previous knowledge. It is essential for ensuring objectivity and reliability in psychological research.

• Steps: Theory, hypothesis, test hypothesis (reject or confirm), revise theory, confirm hypothesis, generate new hypothesis.

• Hypothesis: A testable prediction about processes that can be observed and measured.

• Falsifiability: Hypotheses must be precise enough to be disproven.

• Replication: The process of repeating a study to confirm results.

Critical Thinking in Psychology

Critical thinking involves evaluating evidence, questioning assumptions, and considering alternative explanations.

• Key Steps:

  1. Be curious

  2. Examine the nature and source of evidence

  3. Examine assumptions and biases

  4. Avoid emotional thinking

  5. Tolerate ambiguity

  6. Consider alternative viewpoints

• Empiricism: Knowledge comes from experience and observation.

• Parsimony: Prefer the simplest explanation that fits the data.

Reading and Evaluating Scientific Research

Variables and Measurement

Variables are objects, concepts, or events being controlled, manipulated, or measured by scientists.

• Operational Definitions: Statements that describe procedures or operations used to record observations (e.g., behavioral measures, physiological measures).

• Reliability: Consistency and stability of measurement across multiple observations.

• Validity: The degree to which a test measures what it claims to measure.

• Objectivity: independent of observer

• Generalizability: applies to other populations

• Correlation: NEVER causation

🧠 15-SECOND EXAM MEMORY LOCK

Say this once before the test:

Observe → Question → Hypothesis → IV/DV → Operationalize → Test → Analyze → Conclude → Replicate

Sampling and Data Collection

• Population: The group that researchers want to generalize about.

• Sample: A subset of the population.

• Random Sampling: Every individual in the population has an equal chance of being selected.

• Convenience Sampling: Individuals who are most readily available.

Experimental Design

• Random Assignment: Technique for dividing samples into groups to minimize bias.

• Independent Variable: Manipulated by the experimenter.

• Dependent Variable: Measured to assess the effect of the independent variable.

• Confounding Variable: Variable outside the researcher's control that could affect results.

• Control Group: Does not receive the treatment or stimulus.

• Experimental Group: Receives the treatment or stimulus.

Types of Research

• Case Study: In-depth analysis of a specific case.

• Naturalistic Observation: Observing behavior in its natural context.

• Surveys: Questionnaires or interviews to gather data.

• Correlational Research: Examines relationships between variables. $r = -1.0$ (perfect negative correlation), $r = +1.0$ (perfect positive correlation)

Biological Psychology

The Nervous System

The nervous system is a complex network of neurons that conveys electrochemical information throughout the body.

• Central Nervous System (CNS): Brain and spinal cord.

• Peripheral Nervous System (PNS): Nerves outside the CNS.

• Somatic Nervous System: Controls voluntary movement.

• Autonomic Nervous System: Controls involuntary functions; subdivided into sympathetic (arousal) and parasympathetic (rest).

Neurons and Neural Communication

• Types of Neurons: Sensory, motor, interneurons.

• Structure: Soma (cell body), dendrites, axon, terminal buttons.

• Myelin Sheath: Insulates axons, speeds transmission.

• Action Potential: Rapid change in voltage in a neuron. $\text{Resting potential} \approx -70 \text{mV}$ $\text{Threshold} \approx -55 \text{mV}$

• Synapse: Gap between neurons where neurotransmitters are released.

Major Brain Structures

• Hindbrain: Basic life functions (e.g., breathing, heart rate).

• Pons: Sleep, wake cycle.

• Medulla: Breathing, heart rate.

• Cerebellum: Coordination, balance.

• Forebrain: Complex cognitive functions.

• Thalamus: Sensory relay station.

• Basal Ganglia: Movement and reward processing.

• Limbic System: Emotion and memory (includes amygdala and hippocampus).

Genetics and Behavior

• Genes: Biological units of heredity, segments of DNA.

• Genotype: Genetic makeup of an organism.

• Phenotype: Observable characteristics.

• Heritability: Variation in phenotype due to genetic differences.

Sensation and Perception

Basic Concepts

Sensation is the process of detecting external events with sense organs and turning those events into neural signals. Perception involves attending to, organizing, and interpreting stimuli.

• Transduction: Specialized receptors transform physical energy into neural signals.

• Priming: Previous exposure to a stimulus influences later responses.

• Types of Sensory Receptors:

  • Vision: Light waves, photoreceptors in the retina.

  • Hearing: Sound waves, hair cells in the cochlea.

  • Taste: Chemicals, taste buds on the tongue.

  • Smell: Chemicals, olfactory receptors.

  • Touch: Pressure, temperature, pain receptors.

Perceptual Processes

• Bottom-Up Processing: Perceiving bits of sensory information and constructing a complex perception.

• Top-Down Processing: Expectations and prior knowledge influence perception.

• Selective Attention: Focusing on certain stimuli while ignoring others.

• Signal Detection Theory: Whether a stimulus is perceived depends on both sensory input and decision criteria.

Vision: Anatomy and Function

• Cornea: Protects and bends light.

• Pupil: Opening to let in light.

• Lens: Changes shape to focus images.

• Retina: Contains photoreceptors (rods and cones).

• Accommodation: Lens changes shape to focus on objects.

• Photoreceptors: Rods (low light, black and white), cones (color, detail).

Other Sensory Systems

• Cochlea: Converts vibrations into neural signals for hearing.

• Semicircular Canals: Balance and spatial orientation.

Psychology: History, Core Ideas, Approaches, Psychologists, and Exam Examples

Core Philosophical Ideas

• Empiricism – knowledge comes from observation and experience; psychology relies on scientific evidence.

• Determinism – behavior is caused by biological, psychological, or environmental factors.

• Biopsychosocial model – behavior and mental health result from biological, psychological, and social influences together.

Early Schools & History of Psychology

Structuralism

• Wilhelm Wundt – founded the first psychology lab.

• Edward Titchener – student of Wundt; developed structuralism.

• Focus: structure of consciousness.

• Method: introspection.

• Question: What is the mind made of?

Functionalism

• William James

• Influenced by Charles Darwin.

• Focus: purpose of behavior and mental processes.

• Question: How does the mind help us adapt?

Behaviorism

• John B. Watson, B.F. Skinner

• Focus: observable behavior.

• Emphasized learning through conditioning.

Learning (Very Testable)

Classical Conditioning

• Ivan Pavlov

• Learning through association.

• Example: associating a sound with food.

Operant Conditioning

• B.F. Skinner

• Learning through consequences.

Reinforcement → increases behavior

• Positive reinforcement: adding something pleasant (reward)

• Negative reinforcement: removing something unpleasant

Punishment → decreases behavior

• Positive punishment: adding something unpleasant

• Negative punishment: removing something pleasant

Other Major Schools

Psychoanalytic

• Sigmund Freud

• Focus: unconscious mind, early childhood experiences.

Humanistic

• Carl Rogers, Abraham Maslow

• Focus: free will, personal growth.

• Rogers: unconditional positive regard

• Maslow: hierarchy of needs

Cognitive Approach

• Focus: thinking, memory, perception, problem solving.

• Known as the cognitive revolution.

Gestalt Psychology

• Focus: perception.

• Key idea: the whole is greater than the sum of its parts.

Key principles:

• Figure–ground

• Proximity

• Similarity

• Closure

• Continuity

Psychophysics (Sensation & Perception)

• Relationship between physical stimuli and perception.

Key figures:

• Ernst Weber – Just Noticeable Difference (JND).

• Gustav Fechner – Fechner’s Law.

• Stanley Stevens – Stevens’ Power Law.

Important Psychologists to Know

Charles Darwin

• Natural selection.

• Influenced functionalism and evolutionary psychology.

Francis Galton

• Intelligence, heredity.

• Associated with eugenics (now rejected as unethical).

Norman Triplett

• Social facilitation – people perform better when others are present.

Hawthorne Effect

• People change behavior because they know they are being observed.

Major Approaches / Types of Psychology + Example Exam Questions

Biological Psychology

How might neurotransmitter imbalances explain depression?

Cognitive Psychology

How does working memory affect learning?

Behavioral Psychology

How could reinforcement or punishment be used to change behavior?

Psychodynamic Psychology

How might unconscious conflicts influence adult behavior?

Humanistic Psychology

How would a humanistic psychologist explain motivation?

Evolutionary Psychology

How might behaviors be explained by survival value?

Sociocultural Psychology

How does culture influence behavior?

Types of Psychologists

• Clinical

• Counselling

• Developmental

• Cognitive

• Biological / Neuropsychological

• Social

• Industrial–organizational

One-Line Exam Memory Hooks

• Empiricism → knowledge through observation

• Determinism → behavior has causes

• Structuralism → structure of consciousness

• Functionalism → purpose of behavior

• Behaviorism → learning through rewards & punishment

• Gestalt → whole > parts

• Darwin → adaptation & survival

• Galton → heredity & eugenics (harmful)

• Triplett → social facilitation

• Hawthorne Effect → behavior changes when observed

• Biopsychosocial → biology + psychology + social context

Neurotransmitters & Hormones (FIRST-YEAR LEVEL)

Dopamine Involved in movement, reward, and motivation.

Serotonin Regulates mood, sleep, and appetite.

GABA Primary inhibitory neurotransmitter (calms neural activity).

Cortisol Hormone involved in long-term stress response.

Melatonin Hormone that regulates sleep-wake cycles.

🧠 Experimental Study

Used for: Cause & effect

✅ Pros

• Can determine cause and effect

• High control over variables

• Strong internal validity

❌ Cons

• Ethical limitations (can’t manipulate everything)

• Artificial settings may reduce realism

• Not always generalizable

Exam tip: Only design that allows causation — this is its biggest strength.

🔗 Correlational Study

Used for: Relationship only

✅ Pros

• Ethical (no manipulation)

• Can study variables that can’t be assigned

• Useful for prediction

❌ Cons

• ❌ Cannot establish causation

• Directionality problem

• Third-variable problem

Exam trap: Correlation ≠ causation (always).

👀 Observational Study

Used for: Natural behavior

✅ Pros

• High ecological validity

• Behavior observed as it naturally occurs

• Useful when manipulation is unethical

❌ Cons

• Observer bias

• No control over variables

• Cannot infer causation

Exam trap: Observation describes behavior, it does NOT explain it.

📝 Survey / Self-Report

Used for: Opinions, attitudes, beliefs

✅ Pros

• Fast and inexpensive

• Can reach large samples

• Good for subjective experiences

❌ Cons

• Social desirability bias

• Memory errors

• Self-report is subjective, not objective

Exam trap: Surveys are efficient, not precise.

🧬 Case Study

Used for: Rare or unique cases

✅ Pros

• In-depth, detailed information

• Useful for rare conditions

• Can generate hypotheses

❌ Cons

• Very low generalizability

• No causation

• Researcher bias possible

Exam trap: One case ≠ population.

🧪 Longitudinal Study

Used for: Change over time

✅ Pros

• Tracks development and change

• Strong for studying long-term effects

• Reduces cohort effects

❌ Cons

• Time-consuming and expensive

• Participant dropout (attrition)

• Practice effects

Exam trap: Great for development, terrible for speed.

⏱ Cross-Sectional Study

Used for: Compare groups at one time

✅ Pros

• Fast and efficient

• No participant dropout

• Cost-effective

❌ Cons

• Cohort effects

• Cannot show individual change

• Less developmental accuracy

Exam trap: Group differences ≠ developmental change.

🧠 NERVOUS SYSTEM vs 🧪 ENDOCRINE SYSTEM

(Psych 1 — definitions, functions, pros & cons)

🧠 NERVOUS SYSTEM

What it is

A fast communication system that uses electrical impulses and neurotransmitters to control behavior and mental processes.

Main components

• Central Nervous System (CNS): brain and spinal cord

• Peripheral Nervous System (PNS): all nerves outside the CNS

  • Somatic: voluntary movement

  • Autonomic: involuntary

    • Sympathetic (fight or flight)

    • Parasympathetic (rest and digest)

What it controls

• Movement

• Sensation

• Reflexes

• Thoughts, emotions, decision-making

• Immediate responses to the environment

✅ Pros

• Very fast response (milliseconds)

• Highly precise (specific muscles or glands)

• Ideal for short-term, immediate actions

❌ Cons

• Effects are short-lasting

• Requires direct neural connections

• Less effective for long-term regulation

Exam example

Pulling your hand away from a hot stove → nervous system

🧪 ENDOCRINE SYSTEM

What it is

A slower communication system that uses hormones released into the bloodstream to regulate body processes.

Major glands you must know

• Hypothalamus – control center, links nervous & endocrine

• Pituitary – “master gland”

• Adrenal glands – stress response

• Thyroid – metabolism

• Pineal – melatonin / sleep

• Pancreas – insulin / blood sugar

What it controls

• Growth and development

• Metabolism

• Stress (long-term)

• Mood and energy

• Reproduction

• Sleep cycles

✅ Pros

• Effects are long-lasting

• Influences the whole body

• Excellent for long-term regulation

❌ Cons

• Slow onset (seconds to hours)

• Less precise (hormones circulate everywhere)

• Harder to stop once released

Exam example

Chronic stress increasing cortisol levels → endocrine system

🧠🧪 HOW THEY WORK TOGETHER (VERY TESTED)

• The hypothalamus connects the two systems

• The nervous system triggers the endocrine system during stress

• Example:

  • Nervous system detects threat

  • Hypothalamus activates adrenal glands

  • Cortisol is released

👉 Stress response = BOTH systems

⚖️ SIDE-BY-SIDE COMPARISON (MEMORIZE THIS)

Feature	Nervous System	Endocrine System
Signal type	Electrical + chemical	Hormones (chemical)
Speed	Very fast	Slow
Duration	Short-term	Long-lasting
Precision	Highly specific	Widespread
Best for	Immediate actions	Long-term regulation