Your text describes a study of optimism and health (Peterson et al., 1998) in which participants were first interviewed in the late 1930s and then assessed periodically over the next 50 years. Your knowledge of developmental psychology allows you to identify this as a study.

In a study, people were asked to imagine simple occasions that made them happy and to remember events that made them feel proud about themselves. it was observed that the subjects developed an increasingly positive attitude. these changes are known to be healthy, leading to greater physical activity and reducing unhealthy habits. based on this excerpt, we can conclude that a positive attitude .