Winkielman, P., Knauper, B. & Schwarz, N. (1998). Looking back at anger: Reference periods change the interpretation of emotion frequency questions. Journal of Personality and Social Psychology, 75, 719-728.
When asked about experiences during a specified reference period, participants, as cooperative communicators, draw on the reference period to infer the question meaning. From short reference periods they infer that the question pertains to frequent experiences and from long periods that it pertains to rare ones. Because frequent experiences are typically less intense than rare ones, this shift in question interpretation results in different reports. Three experiments investigated these conversational inference processes in the domain of emotion reports. Participants asked how frequently they get "angry" (a) assumed that the question refers to less intense and more frequent episodes when presented with a short (one week) rather than a long (one year) reference period; (b) reported more extreme episodes in the latter case; and (c) provided differential frequency reports. These differences cannot be explained by memory search biases.