In long-term studies on children some effects can become either accentuated or obscured because children in either the control or experimental groups are maturing at different rates. This threat is known as?

• A. Maturation
• B. History effects
• C. Attrition
• D. Testing effects

Answer: (A)

Maturation refers to natural developmental changes that occur over time. In longitudinal studies with children, these changes can shift abilities and behaviors independently of any intervention. If children in the control and experimental groups mature at different rates, the differences observed at follow-up may reflect where each group is developmentally rather than the treatment itself. This can make effects look larger than they are (accentuated) or smaller (obscured), depending on how maturation progresses in each group. History effects would involve external events between measurements, attrition is about dropout bias, and testing effects are practice-related changes from repeated testing, none of which best capture the described scenario.