Psychological Science Key Terms
CHAPTER ONE (INTRODUCTION)
Psychological Science: The study of the mind, brain, and behavior.
Culture: The beliefs, values, rules, and customs that exist within a group of people who
share a common language and environment and that are transmitted through learning
from one generation to the next.
Nature/Nurture Debate: The arguments concerning whether psychological
characteristics are biologically innate or acquired through education, experience, and
Mind/Body Problem: A fundamental psychological issue that considers whether mind
and body are separate and distinct or whether the mind is simply the subjective
experience of the physical brain.
Evolutionary Theory: In psychological science, a theory that emphasizes the inherited,
adaptive value of behavior and mental activity throughout the history of a species.
Adaptations: In evolutionary theory, the physical characteristics, skills, or abilities that
increase the chances of reproduction or survival and are therefore likely to be passed
along to future generations.
Natural Selection: Darwin’s theory that those who inherit characteristics that help them
adapt to their particular environments have a selective advantage over those who do not.
Introspection: A systematic examination of subjective mental experiences that requires
people to inspect and report on the content of their thoughts.
Structuralism: An approach to psychology based on the idea that conscious experience
can be broken down into its basic underlying components or elements.
Stream Of Consciousness: A phrase coined by William James to describe one’s
continuous series of ever-changing thoughts.
Functionalism: An approach to psychology concerned with the adaptive purpose, or
function, of mind and behavior.
Gestalt Theory: A theory based on the idea that the whole of personal experience is
different from simply the sum of its constituent elements.
Unconscious: The mental processes that operate below the level of conscious awareness.
Psychoanalysis: A method developed by Sigmund Freud that attempts to bring the
contents of the unconscious into conscious awareness so that conflicts can be revealed. Behaviourism: A psychological approach that emphasizes the role of environmental
forces in producing behaviour.
Cognitive Psychology: The study of how people think, learn, and remember.
Cognitive Neuroscience: The study of the neural mechanisms that underlie thought,
learning, and memory.
Social Psychology: The study of group dynamics in relation to psychological processes.
Critical Thinking: A systematic way of evaluating information to reach reasonable
CHAPTER TWO (RESEARCH METHODOLOGY)
Scientific Method: A systematic procedure of observing and measuring phenomena to
answer questions about what happens, when it happens, what causes it, and why.
Theory: A model of interconnected ideas and concepts that explains what is observed
and makes predictions about future events.
Hypothesis: A specific prediction of what should be observed in the world if a theory is
Research: Scientific process that involves the systematic and careful collection of data.
Data: Objective observations or measurements.
Replication: Repetition of an experiment to confirm the results.
Variable: Something in the world that can be measured and that can vary.
Naturalistic Observation: A passive descriptive study in which observers do not change
or alter ongoing behaviour.
Participant Observation: A type of descriptive study in which the researcher is actively
involved in the situation.
Observer Bias: Systematic errors in observation that occur because of an observer’s
Experimenter Expectancy Effect: Actual change in the behavior of the people or
animals being observed that is due to observer bias.
Correlational Study: A research method that examines how variables are naturally
related in the real world, without any attempt by the researcher to alter them. Directionality Problem: When researchers find a relationship between two variables in a
correlational study, they cannot determine which variable may have caused changes in
the other variable.
Third Variable Problem: When the experimenter cannot directly manipulate the
independent variable and therefore cannot be confident that another, unmeasured variable
is not the actual cause of differences in the dependent variable.
Experiment: A study that tests causal hypotheses by measuring and manipulating
Control (Or Comparison) Group: The participants in a study that receive no
intervention or an intervention different from the one being studied.
Experimental (Or Treatment) Group: The participants in a study that receive the
Independent Variable: In an experiment, it is the condition that is manipulated by the
experimenter to examine its impact on the dependent variable.
Dependent Variable: In an experiment, it is the measure that is affected by manipulation
of the independent variable.
Confound: Anything that affects a dependent variable and may unintentionally vary
between the experimental conditions of a study.
Population: Everyone in the group the experimenter is interested in.
Sample: A subset of a population.
Selection Bias: When participants in different groups in an experiment differ
Random Assignment: The procedure for placing research participants into the
conditions of an experiment in which each participant has an equal chance of being
assigned to any level of the independent variable.
Meta-Analysis: A “study of studies” that combines the findings of multiple studies to
arrive at a conclusion.
Culturally Sensitive Research: Studies that take into account the ways culture affects
thoughts, feelings, and actions.
Observational Technique: A research method of careful and systematic assessment and
coding of overt behaviour. Reactivity: When the knowledge that one is being observed alters the behavior being
Self-Report Method: A method of data collection in which people are asked to provide
information about themselves, such as in questionnaires or surveys.
Response Performance: A research method in which researchers quantify perceptual or
cognitive processes in response to a specific stimulus.
Electroencephalograph (EEG): A device that measures electrical activity in the brain.
Brain Imaging: A range of experimental techniques that make brain structures and brain
Positron Emission Tomography (PET): A method of brain imaging that assesses
metabolic activity by using a radioactive substance injected into the bloodstream.
Magnetic Resonance Imaging (MRI): A method of brain imaging that produces high-
quality images of the brain.
Functional Magnetic Resonance Imaging (fMRI): An imaging technique used to
examine changes in the activity of the working human brain.
Transcranial Magnetic Stimulation (TMS): The use of strong magnets to briefly
interrupt normal brain activity as a way to study brain regions.
Research Ethics Boards (REBs): Groups of people responsible for reviewing proposed
research to ensure that it meets the accepted standards of science and provides for the
physical and emotional well-being of research participants.
Validity: The extent to which the data collected address the research hypothesis in the
Reliability: the extent to which a measure is stable and consistent over time in similar
Accuracy: the extent to which an experimental measure is free from error.
Descriptive Statistics: Overall summary of data.
Central Tendency: A measure that represents the typical behavior of the group as a
Mean: A measure of central tendency that is the arithmetic average of a set of numbers.
Median: A measure of central tendency that is the value in a set of numbers that falls exactly halfway between the lowest and highest values.
Mode: A measure of central tendency that is the most frequent score or value in a set of
Variability: In a set of numbers, how widely dispersed the values are from each other
and from the mean.
Standard Deviation: A statistical measure of how far away each value is, on average,
from the mean.
Inferential Statistics: A set of procedures used to make judgments about whether
differences actually exist between sets of numbers.
CHAPTER THREE (BIOLOGICAL FOUNDATIONS)
Chromosomes: Structures within the cell body that are made up of genes.
Gene: The unit of heredity that determines a particular characteristic in an organism.
Dominant Gene: A gene that is expressed in the offspring whenever it is present.
Recessive Gene: A gene that is expressed only when it is matched with a similar gene
from the other parent.
Genotype: The genetic constitution determined at the moment of conception.
Phenotype: Observable physical characteristics that result from both genetic and
Monozygotic Twins: Twin siblings who result from one zygote splitting in two and
therefore share the same genes (i.e., identical twins).
Dizygotic Twins: Twin siblings who result from two separately fertilized eggs (i.e.,
Heritability: A statistical estimate of the variation, caused by differences in heredity, in a
trait within a population.
Neuron: The basic unit of the nervous system; it operates through electrical impulses,
which communicate with other neurons through chemical signals. Neurons receive,
integrate, and transmit information in the nervous system.
Sensory Neurons: One of the three types of neurons, these afferent neurons detect
information from the physical world and pass that information along to the brain. Motor Neurons: One of the three types of neurons, these efferent neurons direct muscles
to contract or relax, thereby producing movement.
Interneurons: One of the three types of neurons, these neurons communicate only with
other neurons, typically within a specific brain region.
Dendrites: Branchlike extensions of the neuron that detect information from other
Cell Body: In the neuron, it is where information from thousands of other neurons is
collected and processed.
Axon: A long narrow outgrowth of a neuron by which information is transmitted to other
Terminal Buttons: Small nodules, at the ends of axons, that release chemical signals
from the neuron to the synapse.
Synapse, Or Synaptic Cleft: The site for chemical communication between neurons,
which contains extracellular fluid.
Myelin Sheath: A fatty material, made up of glial cells, that insulates the axon and
allows for the rapid movement of electrical impulses along the axon.
Nodes of Ranvier: Small gaps of exposed axon, between the segments of myelin sheath,
where action potentials are transmitted.
Resting Membrane Potential: The electrical charge of a neuron when it is not active.
Action Potential: The neural impulse that passes along the axon and subsequently causes
the release of chemicals from the terminal buttons.
All-Or-None Principle: The principle whereby a neuron fires with the same potency
each time, although frequency can vary; it either fires or not – it cannot partially fire.
Neurotransmitter: A chemical substance that carries signals from one neuron to another.
Receptors: In neurons, specialized protein molecules, on the postsynaptic membrane,
that neurotransmitters bind to after passing across the synaptic cleft.
Reuptake: The process whereby a neurotransmitter is taken back into the presynaptic
terminal buttons, thereby stopping its activity.
Agonist: Any drug that enhances the actions of a specific neurotransmitter.
Antagonist: Any drug that inhibits the action of a specific neurotransmitter. Acetylcholine (ACh): The neurotransmitter responsible for motor control at the junction
between nerves and muscles; also involved in mental processes such as learning,
memory, sleeping, and dreaming.
Epinephrine: The neurotransmitter responsible for adrenaline rushes, bursts of energy
caused by its release throughout the body.
Norepinephrine: The neurotransmitter involved in states of arousal and awareness.
Serotonin: A monoamine neurotransmitter important for a wide range of psychological
activity, including emotional states, impulse control, and dreaming.
Dopamine: A monoamine neurotransmitter involved in reward, motivation, and motor
Parkinson’s Disease (PD): A neurological disorder that seems to be caused by dopamine
depletion, marked by muscular rigidity, tremors, and difficulty initiating voluntary action.
GABA: (gamma-aminobutyric acid) The primary inhibitory transmitter in the
Glutamate: The primary excitatory transmitter in the nervous system.
Endorphins: A neurotransmitter involved in natural pain reduction and reward.
Substance P: A neurotransmitter involved in pain perception.
Central Nervous System (CNS): The brain and spinal cord.
Peripheral Nervous System (PNS): All nerve cells in the body that are not part of
the central nervous system. The PNS includes the somatic and autonomic nervous
Broca’s Area: The left frontal region of the brain, crucial for the production of
Brain Stem: A section of the bottom of the brain, housing the most basic programs
of survival, such as breathing, swallowing, vomiting, urination, and orgasm.
Cerebellum: A large, convoluted protuberance at the back of the brain stem,
essential for coordinated movement and balance.
Hypothalamus: A small brain structure that is vital for temperature regulation,
emotion, sexual behavior, and motivation.
Thalamus: The gateway to the brain; it receives almost all-incoming sensory
information before that information reaches the cortex. Hippocampus: A brain structure important for the formation of certain types of
Amygdala: A brain structure that serves a vital role in our learning to associate
things with emotional responses and in processing emotional information.
Basal Ganglia: A system of subcortical structures that are important for the
initiation of planned movement.
Cerebral Cortex: The outer layer of brain tissue, which forms the convoluted
surface of the brain.
Occipital Lobes: Regions of the cerebral cortex, at the back of the brain, important
Parietal Lobes: Regions of the cerebral cortex, in front of the occipital lobes and
behind the frontal lobes, important for the sense of touch and of the spatial layout of
Temporal Lobes: The lower region of the cerebral cortex, important for processing
auditory information and for memory.
Frontal Lobes: The region at the front of the cerebral cortex concerned with
planning and movement.
Prefrontal Cortex: A region of the frontal lobes, especially prominent in humans,
important for attention, working memory, decision making, appropriate social
behavior, and personality.
Somatic Nervous System: A major component of the peripheral nervous system; it
transmits sensory signals to the CNS via nerves.
Autonomic Nervous System (ANS): A major component of the peripheral nervous
system; it regulates the body’s internal environment by stimulating glands and by
manipulating internal organs such as the heart, gall bladder, and stomach.
Sympathetic Division Of ANS: A division of the autonomic nervous system; it
prepares the body for action.
Parasympathetic Division Of ANS: A division of the autonomic nervous system; it
returns the body to its resting state.
Endocrine System: A communication system that uses hormones to influence
thoughts, behaviours, and actions. Hormones: Chemical substances, typically released from endocrine glands, that
travel through the bloodstream to targeted tissues, which are subsequently
influenced by the hormones.
Gonads: The main endocrine glands involved in sexual behavior: in males, the
testes; in females, the ovaries.
Pituitary Gland: Located at the base of the hypothalamus; the gland that sends
hormonal signals controlling the release of hormones from endocrine glands.
Plasticity: A property of the brain that allows it to change as a result of experience,
drugs, or injury.
CHAPTER FOUR (THE MIND AND CONSCIOUSNESS)
Consciousness: The subjective experience of the world and of mental activity.
Split Brain: A condition in which the corpus callosum is surgically cut and the two
hemispheres of the brain do not receive information directly from each other.
Interpreter: A left hemisphere process that attempts to make sense of events.
Subliminal Perception: Information processed without conscious awareness.
Blindsight: A condition in which people who are blind have some spared visual
capacities in the absence of any visual awareness.
REM Sleep: The stage of sleep marked by rapid eye movements, dreaming, and
paralysis of motor systems.
Insomnia: A disorder characterized by an inability to sleep.
Sleep Apnea: A disorder in which a person stops breathing while asleep.
Narcolepsy: A sleep disorder in which people fall asleep during normal waking
Microsleeps: Brief, unintended sleep episodes, ranging from a few seconds to a
minute, caused by chronic sleep deprivation.
Circadian Rhythms: The regulation of biological cycles into regular patterns.
Dreams: The product of an altered state of consciousness in which images and
fantasies are confused with reality.
Manifest Content: The plot of a dream; the way a dream is remembered. Latent Content: What a dream symbolizes, or the material that is disguised in a
dream to protect the dreamer.
Activation- Synthesis Hypothesis: A theory of dreaming that proposes that neural
stimulation from the pons activates mechanisms that normally interpret visual
Hypnosis: A social interaction during which a person, responding to suggestions,
experiences changes in memory, perception, and/or voluntary action.
Meditation: A mental procedure that focuses attention on an external object or on a
sense of awareness.
CHAPTER FIVE (SENSATION AND PERCEPTION)
Sensation: The sense organs’ responses to external stimuli and the transmission of
these responses to the brain.
Perception: The processing, organization, and interpretation of sensory signals; it
results in an internal representation of the stimulus.
Transduction: A process by which sensory receptors produce neural impulses
when they receive physical or chemical stimulation.
Signal Detection Theory (SDT): A theory of perception based on the idea that the
detection of a faint stimulus requires a judgment-it is not an all-or-none process.
Gustation: The sense of taste.
Taste Buds: Sensory receptors that transduce taste information.
Olfaction: The sense of smell, which occurs when receptors in the nose respond to
Olfactory Epithelium: The thin layer of tissue, within the nasal cavity, that is
embedded with smell receptors.
Olfactory Bulb: The brain center for smell, located below the frontal lobes.
Haptic Sense: The sense of touch.
Audition: The sense of sound perception.
Sound Wave: The pattern of the changes in air pressure through time that results in
the percept of a sound. Eardrum (Tympanic Membrane): A thin membrane, which sound waves vibrate,
that marks the beginning of the middle ear.
Cornea: The clear outer covering of the eye.
Retina: The thin inner surface of the back of the eyeball. The retina contains the
photoreceptors that transduce light into neural signals.
Pupil: The small opening in the eye; it lets in light waves.
Iris: The coloured muscular circle on the surface of the eye; it changes shape to let
in more or less light.
Rods: Retinal cells that respond to low levels of illumination and result in black-
Cones: Retinal cells that respond to higher levels of illumination and result in colour
Fovea: The center of the retina, where cones are densely packed.
Receptive Field: The region of visual space to which neurons in the primary visual
cortex are sensitive.
Lateral Inhibition: A visual process in which adjacent photoreceptors tend to
inhibit one another.
Subtractive Colour Mixing: A way to produce a given spectral pattern in which the
mixture occurs within the stimulus itself and is actually a physical, not
Additive Colour Mixing: A way to produce a given spectral pattern in which
different wavelengths of light are mixed. The percept is determined by the
interaction of these wavelengths with receptors in the eye and is a psychological
Kinesthetic Sense: Perception of our limbs in space.
Vestibular Sense: Perception of balance.
Bottom-Up Processing: A hierarchal model of pattern recognition in which data
are relayed from one processing level to the next, always moving to a higher level of
processing. Top-Bottom Processing: A hierarchal model of pattern recognition in which
information at higher levels of processing can also influence lower, “earlier” levels in
the processing hierarchy.
Binocular Depth Cues: Cues of depth perception that arise from the fact that
people have two eyes.
Monocular Depth Cues: Cues of depth perception that are available to each eye
Binocular Disparity: A cue of depth perception that is caused by the distance
between a person’s eyes, which provides each eye with a slightly different image.
Perceptual Constancy: People correctly perceive objects as constant in their shape,
size, colour, and lightness, despite raw sensory data that could mislead perception.
CHAPTER SIX (LEARNING)
Learning: An enduring change in behavior, resulting from experience.
Classical Conditioning or Pavlovian Conditioning: A type of learned response
that occurs when a neural object comes to elicit a reflective response when it is
associated with a stimulus that already produces that response.
Unconditioned Response (UR): A response that does not have to be learned, such
as a reflex.
Unconditioned Stimulus (US): A stimulus that elicits a response, such as a reflex,
without any prior learning.
Conditioned Stimulus (CS): A stimulus that elicits a response only after learning
has taken place.
Conditioned Response (CR): A response to a conditioned stimulus that has been
Acquisition: The gradual formation of an association between the conditioned and
Extinction: A process in which the conditioned response is weakened when the
conditioned stimulus is repeated without the unconditioned stimulus.
Spontaneous Recovery: A process in which a previously extinguished response re-
emerges following presentation of the conditioned stimulus. Stimulus Generalization: Occurs when stimuli that are similar but not identical to
the conditioned stimulus produce the conditioned response.
Stimulus Discrimination: A differentiation between two similar stimuli when only
one of them is consistently associated with the unconditioned stimulus.
Phobia: An acquired fear that is out of proportion to the real threat of an object or
of a situation.
Rescoria-Wagner Model: A cognitive model of classical conditioning; it states that
the strength of the CS-US association is determined by the extent to which the
unconditioned stimulus is unexpected.
Operant Conditioning, Or Instrumental Conditioning: A learning process in
which the consequences of an action determine the likelihood that it will be
performed in the future.
Law Of Effect: Thorndike’s general theory of learning: Any behavior that leads to a
“satisfying state of affairs” will more likely occur again, and any behavior that leads
to an “annoying state of affairs” will less likely recur.
Reinforcer: A stimulus that follows a response and increases the likelihood that the
response will be repeated.
Shaping: A process of operant conditioning; it involves reinforcing behaviours that
are increasingly similar to the desired behaviour.
Positive Reinforcement: The increase in the probability of a behaviour’s being
repeated following the administration of a stimulus.
Negative Reinforcement: The increase in the probability of a behaviour’s being
repeated through the removal of a stimulus.
Positive Punishment: Punishment that occurs with the administration of a
stimulus and thus decreases the probability of a behaviour’s recurring.
Negative Punishment: Punishment that occurs with the removal of a stimulus and
thus decreases the probability of a behaviour’s recurring.
Continuous Reinforcement: A type of learning in which the desired behaviour is
reinforced each time it occurs.
Partial Reinforcement: A type of learning in which behaviour is reinforced
intermittently. Ratio Schedule: A schedule in which reinforcement is based on the number of times
the behaviour occurs.
Interval Schedule: A schedule in which reinforcement is available after a specific
unit of time.
Fixed Schedule: A schedule in which reinforcement is consistently provided after a
specific number of occurrences or a specific amount of time.
Variable Schedule: A schedule in which reinforcement is applied at different rates
or at different times.
Partial-Reinforcement Extinction Effect: The greater persistence of behaviour
under partial reinforcement than under continuous reinforcement.
Behaviour Modification: The use of operant-conditioning techniques to eliminate
unwanted behaviours and replace them with desirable ones.
Cognitive Map: A visual/spatial mental representation of an environment.
Latent Learning: Learning that takes place in the absence of reinforcement.
Meme: A unit of knowledge transferred within a culture.
Observational Learning: Learning that occurs when behaviours are acquired or
modified following exposure to others performing the behaviour.
Modelling: The imitation of behaviour through observational learning.
Vicarious Learning: Learning that occurs when people learn the consequences of
an action by observing others being rewarded or punished for performing the
Mirror Neurons: Neurons that are activated during observation of others
performing an action.
Habituation: A decrease in behavioural response following repeated exposure to
Sensitization: An increase in behavioural response following exposure to a
Long-Term Potentiation (LTP): The strengthening of a synaptic connection so that
postsynaptic neurons are more easily activated.
CHAPTER SEVEN (ATTENTION AND MEMORY) Memory: The nervous system’s capacity to acquire and retain usable skills and
Change Blindness: The common failure to notice large changes in environments.
Encoding: The processing of information so that it can be stored.
Storage: The retention of encoded representations over time that corresponds to
some change in the nervous system that registers the event.
Retrieval: The act of recalling or remembering stored information to use it.
Modal Memory Model: The three-stage mem