(AP Psychology) Experimental Psychology - Unit 0

Intuition

Internal feelings or compulsions that often mislead us; scientific methods help correct these errors.

Bias

A tendency to favor or support one's own narrow views, which can distort results.

Operational definition

Exact procedures used in research, allowing replication of experiments.

Hypothesis

A testable prediction yet to be confirmed or rejected by experiment.

Theories

Well-supported explanations that organize observations and predict outcomes.

Experimental Group

The group exposed to the treatment (e.g., receiving Vitamin D supplements).

Control Group

The group not exposed to the treatment (e.g., receiving a placebo).

Single Blind

Participants or researchers are unaware of which treatment is given, but not both.

Double Blind

Both participants and researchers are unaware of who receives the treatment or placebo.

Dependent Variable

The factor measured in an experiment (the outcome).

Independent Variable

The factor manipulated by researchers to test its effect.

Random Selection

Choosing a representative sample randomly from a population to avoid bias.

Random Assignment

Randomly assigning selected participants to experimental or control groups.

Convenience Sampling

Choosing participants due to accessibility, reducing research integrity.

Confounding Variables

Unwanted variables that may affect results if not controlled.

Control Variables

Factors deliberately kept constant to reduce confounding effects.

Sampling Bias

When some members of the intended population are less likely to be included in the sample.

Social Desirability Bias

When participants alter responses to appear favorable to others.

Experimenter Bias

When researchers influence results, consciously or unconsciously.

Correlations Study

Examines the relationship between two factors but does not prove causation.

Naturalistic Observation

Observing behavior in its natural environment without interference.

Case Study

In-depth study of one person or group to reveal universal truths.

Meta Analysis

Statistical method combining results of multiple studies for stronger conclusions.

Bar Graphs

Graphs with gaps between bars, showing categories vs. numerical values.

Histograms

Graphs with no gaps between bars, showing frequency distribution.

Qualitative Measures

Non-numerical data collection (interviews, observations).

Quantitative Measures

Numerical data collection (scales, scores) for statistical analysis.

Scatterplot

Graph showing the relationship between two variables using plotted points.

Correlation Coefficient

Statistical value (-1 to 1) showing strength and direction of a relationship.

Positive Correlation

As one variable increases, the other also increases.

Negative Correlation

As one variable increases, the other decreases.

Positive Skew

Distribution where most data is clustered on the left, tail stretches right.

Negative Skew

Distribution where most data is clustered on the right, tail stretches left.

Bimodal

A frequency distribution with two peaks.

Bell Curve

A normal distribution with one peak, shaped like a bell.

Mode

The most frequently occurring score in a dataset.

Mean

The arithmetic average of scores.

Range

The difference between the highest and lowest scores.

Median

The middle score in a dataset (half above, half below).

Standard Deviation

A measure of how spread out scores are from the mean.

Percentile

Indicates the value below which a percentage of scores fall (e.g., 90th percentile).

Statistical Significance

The likelihood that results are not due to chance.

Peer Review

Evaluation of research by experts before publication.

Replication

Repeating an experiment under the same conditions to confirm results.