The uncontrollable nature of involuntary autobiographical memories has posed a major obstacle against experimental examination. Although involuntary conscious memories were described as a basic form of remembering by Ebbinghaus in 1885 in the world’s first book on experimental research on human memory, such memories have been generally ignored by later memory researchers. George Miller, a founding father of cognitive psychology, even deemed them “the complete antithesis of all we have learned to call scientific” because the scientist would have “no way to capture the things he wishes to study. He can only sit and wait, hoping for the improbable” (Miller, 1962, p. 180). However, recently, we succeeded at developing an experimental paradigm in which–for the first time–the activation of involuntary memories was controlled and predicted on the basis of manipulations done at encoding. We showed that involuntary memories can be induced in the laboratory and that they arise as a result of high levels of cue-item discriminability. A cue has high discriminability if it is associated with just one event (e.g., a song heard only once), whereas a cue associated with many events (e.g., a song heard at many occasions) has low discriminability and is unlikely to activate a memory about a specific occasion. This principle is well-known from the verbal learning literature but has not been applied to research on involuntary autobiographical memories before. In a real-life context, it ensures that we are not constantly flooded by involuntary memories because relatively few situations provide a sufficiently high cue discriminability to trigger a memory. This mechanism also optimizes the probability that the activated memory will contain information of relevance for the ongoing situation because of the distinct feature overlap being needed for its activation.
In addition to experimental research in laboratory settings, we continue to conduct various kinds of naturalistic studies examining the occurrence and prevalence of involuntary and voluntary (deliberate) memories in everyday life. Among other things, this research has shown that involuntary autobiographical memories are at least as frequent as memories that are deliberately retrieved, that they are cue dependent and often come to mind in situations with diffuse attention. Our research has also shown substantial individual variability concerning their frequency, and it is one of our goals to study demographic and dispositional correlates of this variability.