Psychology, Neuroscience, and Sensory Perception: Key Concepts and Connections

Psychology

The scientific study of mind and behavior.

Structuralism

Asks what conscious experience is made of—its basic components.

Functionalism

Asks what mental processes and behaviors do and why they may be useful/adaptive.

Introspection

Reporting on your own conscious experiences.

Nativism

Some knowledge/abilities are innate.

Empiricism

Knowledge comes through experience.

Dualism

Mind and body are separate.

Materialism

Mental processes arise from physical matter/brain activity.

Realism

An external world exists independently of perception.

Idealism

Knowledge of reality is mediated by the mind/perception.

Reactivity

Occurs when people change their behavior because they know they are being observed or measured.

Demand characteristics

Happen when participants figure out what a study is testing and change their behavior based on what they think the researcher expects.

Correlation

Describes the relationship between two variables, ranging from -1 to +1.

Positive correlation

As one variable increases, the other tends to increase.

Negative correlation

As one variable increases, the other tends to decrease.

Operational definition

Explains exactly how a variable will be measured or manipulated.

Reliability

Consistency of a measure.

Validity

Whether the measure actually measures what it is supposed to measure.

Internal validity

Can we conclude that the IV caused the DV?

External validity

Can we generalize the findings beyond the study/sample?

Frequency distribution

Organizes scores and shows how often each score or range occurs.

Mean

Arithmetic average.

Median

Middle score when ordered.

Mode

Most frequent score.

Third-variable problem

If two variables correlate, a third variable may influence both.

Experiment

Involves manipulating an independent variable (IV), measuring a dependent variable (DV), and using control/randomization procedures to test causal relationships.

Population

Entire group of interest.

Sample

Smaller group actually studied.

Random sampling

Helps determine who gets into the study and supports generalization.

Random assignment

Determines which condition participants enter and helps establish causal conclusions.

Type I error

False positive: concluding there is an effect when there is not.

Type II error

False negative: failing to detect an effect that exists.

Neuron structure

Information generally travels dendrites → soma/cell body → axon → axon terminals.

Myelin

Fatty insulation around many axons that increases the speed and efficiency of neural communication.

Sensory neurons

Carry information from receptors toward the nervous system.

Motor neurons

Carry commands toward muscles/glands.

Interneurons

Connect neurons within the nervous system.

Action potential

Occurs when input reaches threshold: rapid depolarization, followed by repolarization, then a refractory period.

Synapse

At the axon terminal, an action potential can cause neurotransmitter release into the synaptic cleft.

Presynaptic

Sending side.

Postsynaptic

Receiving side.

Neurotransmitter clearance

Signals end through processes such as reuptake into the presynaptic neuron or enzyme deactivation.

Dopamine

Involved in movement, reward, motivation, and learning.

Serotonin

Involved in mood and many other functions.

GABA

Generally decreases neural activity.

Acetylcholine

Important for muscle action and other functions.

Glutamate

Major excitatory neurotransmitter.

Agonist

Increases/imitates a neurotransmitter's action at a receptor.

Antagonist

Blocks or reduces a neurotransmitter's action.

CNS

Central nervous system (brain + spinal cord).

PNS

Peripheral nervous system (nerves outside the brain and spinal cord).

Sympathetic

Mobilizes the body for action ('fight or flight').

Parasympathetic

Supports rest, recovery, and digestion.

Spinal reflex

A reflex can be processed through the spinal cord before conscious brain processing.

Brain Organization

The brain can be discussed in broad regions: hindbrain, midbrain, forebrain.

Hindbrain

Includes structures important for basic survival and coordination.

Midbrain

Involved in movement and sensory functions.

Forebrain

Includes structures supporting complex cognition, emotion, memory, and perception.

Thalamus

A major sensory relay station, directing much sensory information toward the appropriate cortical areas.

Hypothalamus

Helps regulate homeostasis and motivated behaviors such as hunger, thirst, temperature regulation, and related hormonal processes.

Hippocampus

Strongly associated with memory formation and spatial/contextual memory.

Amygdala

Involved in emotional processing, especially threat/fear-related learning and responses.

Hemispheres

The left hemisphere generally controls the right side of the body, while the right hemisphere generally controls the left.

Somatosensory cortex

Processes body sensations.

Motor cortex

Controls voluntary movement.

Frontal lobe

Involved in planning, decision-making, impulse control, and movement.

Parietal lobe

Involved in body sensation and spatial processing.

Temporal lobe

Involved in hearing, language-related processing, memory, and other functions.

Occipital lobe

Involved in vision.

Mirror neurons

Can respond when an action is performed and when a similar action is observed.

Nature vs. nurture

Behavior is shaped by interactions between genes and environment.

Twin studies

Monozygotic (MZ) twins share nearly all of their genetic material, while dizygotic (DZ) twins share about half on average.

Concordance

Concordant means twins share a trait; discordant means they differ.

EEG

Measures electrical brain activity with excellent timing.

MRI

Provides detailed brain structure.

fMRI

Measures changes in blood oxygenation used to estimate activity.

PET

Uses a tracer to study metabolic/functional activity.

TMS

Uses magnetic stimulation to temporarily influence/disrupt activity in a targeted cortical area.

Sensation vs. perception

Sensation is detecting physical energy through sensory systems; perception is organizing and interpreting that information into meaningful experience.

Transduction

The conversion of physical stimulus energy into neural signals.

Absolute threshold

The minimum stimulation detectable about 50% of the time under defined conditions.

Just noticeable difference (JND)

The smallest difference between two stimuli that can be detected reliably under the relevant conditions.

Signal detection theory

Detection depends on both the stimulus and the observer's decision criterion.

Four outcomes in signal detection

Hit: signal present, you say present; Miss: signal present, you say absent; False alarm: signal absent, you say present; Correct rejection: signal absent, you say absent.

Decision criteria

A liberal criterion says 'signal present' with less evidence, producing more hits but also more false alarms.

Light

Visible light is part of the electromagnetic spectrum.

Eye structures

Cornea: clear outer surface that strongly bends incoming light; Lens: changes shape to focus light; Retina: contains photoreceptors and begins neural processing.

Rods vs. cones

Rods are highly sensitive in dim light; cones support color vision and fine detail.

Blind spot

Where the optic nerve exits the eye; that location lacks photoreceptors.

Visual pathway

A simplified pathway is retina → optic nerve → LGN (lateral geniculate nucleus) → primary visual cortex.

Color blindness

Color-vision deficiencies can occur when cone photopigments are absent or function differently.

Trichromatic theory

Explains color perception through the relative activity of three cone types.

Opponent-process theory

Describes color processing in opposing channels such as red-green and blue-yellow.

Single-neuron recording

Recording activity from individual neurons in visual cortex can show that some neurons respond especially strongly to particular visual features.

Gestalt principle: simplicity

The visual system tends to organize information into a simple, stable interpretation.

Continuity

We tend to perceive smooth, continuous patterns rather than abrupt breaks.

Similarity

Objects that look alike are more likely to be grouped together.

Common fate

Objects moving together in the same direction or pattern tend to be perceived as belonging together.

Monocular depth cues

Visual cues that can be perceived with one eye.

Linear perspective

Parallel lines appear to converge with distance.