Carryover effect refers to the relatively permanent effect that testing subjects in one condition has on their later behavior in another condition. Carryover effects are changes in the scores observed in one treatment condition that are caused by the lingering after-effects of a specific earlier treatment condition.
Carstensen was responsible for the Socio-emotional Selectivity Theory proposes that people prune their social networks to maintain a desired emotional state depending on the extent to which time is perceived as limited. Basic functions of social interaction, such as maintaining a good mood, differ in respect to their relative importance for determining social preferences across the lifespan.
A case can refer to a specific individual or group who is being studied or treated. For example, a psychologist might work with a single patient on a one-on-one basis, in which case that patient would be referred to as a "case." Similarly, a group of patients being treated in a group therapy setting might be referred to as a "case group."