Psychology Unit 1

dendrites 

receive messages 

cell body (soma)

processes information, keeps cell alive

axon

carries electrical impulses away from the cell body, sends messages to other neurons 

sensory neurons

carry information from the body to the brain which is the input, while motor neurons transmit signals from the brain to the body, enabling action.

Interneurons

neurons that connect sensory and motor neurons, processing information within the brain and spinal cord, connect neurons with brain and spinal cord 

motor neurons

carry information from brain and spinal cord to muscles and glands which is the output

action potential

electrical impulse down axon, all or none law fires completely or not at all

stimulus intensity 

Encoded by frequency of firing, not strength of each impulse.

myelin

fatty coating on axons, speeds transmission, gaps = nodes of ranvier, damage slows signal

synapse

gap between neurons

electrical communication 

within a neuron 

chemical communication

Between neurons (via neurotransmitters)

Central Nervous System (CNS)

Brain + spinal cord.

Peripheral Nervous System (PNS)

Nerves outside CNS

Somatic NS

Voluntary movement, sensory/motor control

Autonomic NS

Involuntary functions (organs, glands)

Sympathetic

"Fight or flight" (↑ heart rate, ↑ breathing)

Parasympathetic

"Rest and digest" (slows down, restores)

reflexes

Automatic, no brain input needed → processed by spinal cord, ex: knee-jerk reflex

Hindbrain

Basic life functions (breathing, heart rate, coordination

Midbrain

Sensory processing, movement.

Forebrain

Higher functions (thought, emotion, reasoning)

Spinal cord

Communication highway + reflexes

Cerebral Cortex

Outer layer of forebrain; involved in higher-order thinking, planning, perception.

Corpus callosum

Connects left/right hemispheres

Left hemisphere

Language, logic, analysis

Right hemisphere

Creativity, spatial abilities, holistic processing.

Frontal lobe

Planning, reasoning, movement, speech.

Prefrontal cortex

Decision-making, personality, self-control.

Parietal lobe

Sensory processing (touch, body position)

Somatosensory cortex

touch, pain, temperature.

Occipital lobe

Vision

Primary visual cortex

Processes visual input

Temporal lobe

Hearing, language, memory

Primary auditory cortex

Processes sounds

What is Psychology

The scientific study of mind and behavior,

Common sense

Based on personal experience, intuition, or cultural beliefs

Empirical evidence

Based on systematic observation, measurement, and experimentation

Hypothesis

A testable prediction (specific)

Theory

A broad explanation supported by evidence (general

Operational Definitions

Defining variables in measurable terms, Example: “Aggression” = number of times someone hits, yells, or pushes.

Population

Entire group of interest

Sample

Subset studied to represent the population.

Convenience sample

easy to access; less reliable, more bias

Representative sample

Matches key characteristics of population; more accurate but harder to achieve.

Random sample

Every person has equal chance; best for generalizing results.

Cross-cultural sample

Compares different cultures; helps test universality, but costly/complex.

Naturalistic observation

Observe in natural setting; real behavior but no control.

Case study/history

In-depth on one person/group; detailed but not generalizable.

Survey

Large amounts of data fast; may have self-report bias.

Experiment

Controlled test of cause-effect; strongest evidence but less “real world.”

Positive correlation

Variables move in same direction (+)

Negative correlation

Variables move in opposite directions (−).

No correlation

no relationship

Correlation coefficient (r)

Strength of relationship (−1.00 to +1.00).

• r = +0.90 → very strong positive

• r = +0.01 → near zero, very weak

Independent variable (IV)

Manipulated factor

Dependent variable (DV)

Measured outcome

Control

Group without manipulation

Random assignment

Participants randomly placed in groups → reduces bias.

Confounding variable

Uncontrolled factor that affects results

Experimenter bias

Researcher influences results.

Subject bias

Participant alters behavior (e.g., to “look good”)

Placebo effect

Improvement due to belief in treatment

Single blind

Participants don’t know condition

Double blind

Neither participants nor researchers know → prevents bias

Measures of central tendency

• Mean: Average

• Median: Middle value

• Mode: Most frequent

Inferential statistics

Used to generalize results from sample to population

p < 0.05

Results unlikely due to chance → statistically significant.

Statistical significance

Likely not by chance

Practical significance

Real-world importance of results.

Reliability

Consistent results over time.

Validity

Actually measures what it claims to measure

IRB (Institutional Review Board)

Approves and monitors human research

IACUC (Institutional Animal Care and Use Committee)

Oversees ethical animal research.