Which of the following defines a cohort in psychological research?

A cohort in psychological research specifically refers to a group of individuals who were born or experienced a significant life event within the same time frame. This definition highlights the importance of shared temporal characteristics and experiences, which can greatly influence behaviors, attitudes, and developmental trajectories. For example, researchers studying the impact of historical events, such as World War II, might focus on individuals who were adolescents during that time, as their perspectives and life choices may be shaped by the shared experiences of that era.

The other options do not accurately capture the essence of what a cohort is in psychological research. While a group of individuals with shared traits may indeed share some characteristics, it does not necessarily imply that they are linked by the same time period or significant life events. Similarly, a sample of diverse age groups does not describe a cohort, since cohorts typically consist of people within the same age range or who experienced similar events at a similar time. Lastly, referring to a cohort as a research methodology is misleading, as a cohort is more about the characteristics of the subjects involved in a study rather than the method used to conduct the research.