Psych Unit 0

Hypothesis

A testable, falsifiable prediction about how two variables are expected to be related

Mode

Value that occurs most frequently in a distribution

Qualitative Data

Non‑numeric information gathered from interviews, observations, or open‑ended responses

Naturalistic Observation

Systematic recording of behavior in its natural environment without researcher interference

Single‑blind Procedure

Design where participants are unaware of whether they belong to the experimental or control condition

Cohen's d (Small)

Effect size around 0.2, indicating a modest difference between groups

Debriefing

Explanation given to participants after a study, revealing any deception and its purpose

Normal Distribution

Symmetrical, bell‑shaped curve where mean, median, and mode are equal

Case Study

In‑depth examination of a single individual or a small group to explore rare or unique phenomena

Random Sampling

Selection method giving each member of the population an equal chance of being chosen, enhancing representativeness

Negative Skew

Tail extends to the left, resulting in the median being greater than the mean

Correlational Design

Method that assesses the statistical relationship between two variables without manipulating either

Control Group

Group that does not receive the experimental treatment, allowing comparison with the experimental condition

Confounding Variable

Extraneous factor that varies with the independent variable and may provide an alternative explanation for results

Double‑blind Procedure

Design where both participants and experimenters are unaware of group assignments, reducing bias

Social Desirability Bias

Tendency of respondents to answer questions in a manner that will be viewed favorably by others

Replication

Conducting a study anew to verify that its findings hold under similar conditions

Operational Definition

Precise description of how a variable will be measured or manipulated in a study

Anonymity

Collecting data without recording any identifying information about participants

p‑value

Probability that observed data would occur if the null hypothesis were true; lower values suggest statistical significance

Regression Toward the Mean

Phenomenon where extreme scores tend to be followed by scores closer to the average on subsequent measurement

Cohen's d (Large)

Effect size of about 0.8 or greater, representing a pronounced difference

Meta‑analysis

Statistical technique that aggregates findings from multiple studies to determine overall effect sizes

Humanistic Perspective

Highlights personal growth, free will, and the pursuit of self‑actualization as central to psychological health

Positive Skew

Tail stretches to the right, causing the mean to exceed the median

Dependent Variable (DV)

Outcome measure that is recorded to assess the impact of the independent variable

Sample

Subset of the population that actually participates in the research study

Percentile Rank

Percentage of scores in a distribution that fall at or below a specific score

Sociocultural Perspective

Analyzes how social interactions, cultural norms, and societal expectations shape thoughts and actions

Hindsight Bias

Inclination to view past events as having been predictable after they have already occurred

Internal Validity

Extent to which a study can demonstrate a causal relationship between variables, free from confounding influences

Convenient Sampling

Choosing participants who are readily accessible, often leading to sampling bias

Confirmation Bias

Tendency to notice and remember information that supports existing beliefs while disregarding contradictory data

Correlation Coefficient ($r$)

Statistical index ranging from -1 to +1 that reflects the strength and direction of a linear relationship between two variables

Counterargument

Opposing evidence or reasoning that challenges a claim, used to strengthen argumentation when addressed

Statistical Significance

Result indicating that the likelihood of the observed effect occurring by chance is below a predetermined threshold (commonly $p < .05$)

Confidence Interval

Range of values within which the true population parameter is likely to fall, given a specified confidence level

Confidentiality

Ensuring that participant data are kept private and not linked to individual identities

Population

Entire group of individuals to which researchers intend to generalize their findings

Construct Validity

Degree to which a test or measure accurately captures the theoretical construct it intends to assess

Bimodal Distribution

Data set with two distinct peaks, indicating two prevalent values or groups

Placebo

Inert substance or procedure given to control participants to control for expectation effects

Independent Variable (IV)

The factor that researchers actively change or assign to participants to observe its effect

Deception

Providing false information or withholding details about a study's true purpose, permitted only when necessary

Informed Assent

Agreement from a minor participant after their guardian has given consent

Standard Error

Estimate of the variability of a sample mean relative to the true population mean

Biological Perspective

Focus on how brain structures, neurotransmitters, hormones, and genetics influence behavior and mental processes

Directionality Problem

Uncertainty about which variable influences the other in a correlational relationship

Overconfidence Bias

Overestimation of one's knowledge, abilities, or performance accuracy

Median

Middle value of an ordered data set, representing the point at which half the scores are higher and half are lower

Cognitive Perspective

Examines internal mental activities like perception, memory, and problem‑solving to explain behavior

Experimenter Bias

Unintentional influence of a researcher's expectations on participants' behavior or data interpretation

Reliability

Consistency of a measurement instrument across time, items, or observers

Standard Deviation (SD)

Average distance of scores from the mean, indicating how spread out the data are

Cohen's d (Medium)

Effect size near 0.5, signifying a moderate difference

Psychodynamic Perspective

Attributes behavior to unconscious conflicts, childhood experiences, and drives originating from early development

Experimental Design

Research structure that manipulates an independent variable, employs random assignment, and allows causal conclusions

Effect Size ($d$)

Standardized measure of the magnitude of a difference or relationship, independent of sample size

Third‑Variable Problem

Possibility that an unmeasured factor accounts for the observed association between two variables

Quantitative Data

Numerical information that can be subjected to statistical analysis, such as scores or reaction times

External Validity

Degree to which research findings can be generalized beyond the specific sample and setting

Peer Review

Evaluation of a manuscript by independent experts before publication to ensure scientific rigor

Mean

Arithmetic average of a set of scores, calculated by summing all values and dividing by the number of values

Placebo Effect

Improvement in participants caused by their belief that they are receiving an active treatment

Evolutionary Perspective

Considers how natural selection has shaped mental traits that increase reproductive success or survival

Defensible Claim

Clear, specific statement that can be supported with empirical evidence and logical reasoning

Self‑Report Bias

Distortions in participants' own accounts due to lack of insight, memory errors, or intentional deception

Range

Difference between the highest and lowest scores in a data set

Evidence‑Based Reasoning

Process of linking data and research findings to a claim through explanation and justification

Behavioral Perspective

Emphasizes learning principles such as reinforcement and punishment as primary drivers of observable actions

Informed Consent

Process of providing participants with details about a study so they can voluntarily decide to participate