D.3 Identify threats to internal validity (e.g., history, maturation).

Refers to the changes in operant responding due to the repeated presentation of a particular antecedent stimulus.

A reduction in the number of study participants, which can impact the validity and reliability of the findings and compromise the integrity of the data.

Reinforcement that is accessed without meeting the response requirements of the contingency.

Any aspect of the environment that must be held constant to prevent unplanned environmental variations during experimentation, usually something the experimenter is aware of and for which they do their

Uncontrolled environmental variables that may interfere with the outcomes and/or the effectiveness of an intervention and therefore the internal validity of the experiment.

Refers to the changes in a subject over the course of the study that result from natural growth and development.

Uncontrolled variables related to the environment, the measurement tools, or a data collector’s behavior that may interfere with the measurement of behavior and therefore impact the outcomes and/or the effectiveness

Refers to an improvement in responding from the opportunity to practice a behavior, specifically during prolonged baseline measurement periods.

Refers to the changes in an individual’s behavior due to the presence of an observer.

Any uncontrolled variables in the treatment setting that could impact the outcomes and/or the effectiveness of an intervention and therefore the internal validity of the experiment.