Longitudinal studies are characterized by what main aspect?

Longitudinal studies are primarily defined by their focus on following the same individuals over an extended period. This method allows researchers to observe changes over time within the same population, making it possible to assess development, behavior, and other psychological factors as they evolve. By repeatedly measuring the same subjects at various time points, longitudinal studies provide insights into how individuals change and grow, facilitating a deeper understanding of lifespan development.

This approach contrasts with other research methods. For example, studying different individuals at once constitutes a cross-sectional study, which captures a moment in time but does not provide insights into developmental trends within individuals. Analyzing a single snapshot of time also limits the understanding of changes that occur over time. While comparing different generations offers valuable perspectives, it does not involve tracking the same individuals, which is the hallmark of longitudinal studies. Thus, the key aspect that characterizes longitudinal studies is the consistent observation of the same participants throughout their development.