Which study aims to observe change directly as it occurs by testing subjects repeatedly over a short period?

The microgenetic study is specifically designed to observe changes as they occur in real-time by repeatedly testing subjects over a short period. This approach allows researchers to capture the process of change and the development of skills or behaviors as they unfold, providing insight into the mechanisms behind developmental progression.

In contrast, cohort studies typically examine groups of individuals who share a common characteristic over time but may not focus on immediate changes. Longitudinal studies involve following the same subjects over an extended period but may not provide the granularity of change observed in a microgenetic approach. Cross-sectional studies capture data at a single point in time, making them unsuitable for tracking changes over a short period. The emphasis of a microgenetic study on close observation and frequent assessment is what distinguishes it as the correct answer in this context.