Name a historical threat to internal validity where events outside the study influence participants.

• A. Maturation.
• B. History.
• C. Instrumentation.
• D. Selection bias.

Answer: (B)

This item focuses on how events happening outside the study can influence participants during the measurement period, which threatens internal validity. History refers to those external events that occur between measurements and affect the dependent variable for participants in the study, potentially confounding the treatment effect. For example, if a survey measures attitudes before and after an intervention and a major news event or policy change happens in between, that outside event could shift responses regardless of the intervention itself. Maturation would involve changes within participants over time, such as aging or fatigue, rather than external happenings. Instrumentation means the measurement tools or procedures change between assessments. Selection bias involves pre-existing differences between groups due to how participants were chosen or assigned. Because history specifically captures external events that impact participants during the study, it best fits the described threat.