A demonstration that the hippocampus supports both recollection and familiarity

Abstract

Recognition memory is thought to depend on two distinct processes: recollection and familiarity. There is debate as to whether damage to the hippocampus selectively impairs recollection or whether it impairs both recollection and familiarity. If hippocampal damage selectively impairs recollection but leaves familiarity intact, then patients with circumscribed hippocampal lesions should exhibit the full normal range of low-confidence and high-confidence familiarity-based recognition. High-confidence, familiarity-based decisions are ordinarily accompanied by successful recollection (when memory is intact). However, patients with hippocampal lesions, if recollection is impaired, should frequently experience high-confidence, familiarity-based recognition in the absence of recollection, and this circumstance (termed the "butcheron-the-bus" phenomenon) should occur more often in patients than in healthy controls. We tested five patients with circumscribed hippocampal damage, asking them to recognize recently studied words as well as to remember the context in which the items were studied. Relative to controls, the patients exhibited no increased tendency to experience the butcher-on-the-bus phenomenon. The simplest explanation of the results is that hippocampal damage impairs familiarity as well as recollection. The same conclusion was suggested when two competing models of recognition memory were used to analyze the data.amnesia | recognition | source memory T he ability to accurately recognize a previously encountered item is generally thought to be based on two processes: recollection and familiarity. Recollection involves remembering the source of a prior encounter, whereas familiarity involves simply knowing that the item was previously encountered despite the absence of any information about its source. The following anecdote, offered by Mandler (1), illustrates these two processes:Consider seeing a man on a bus whom you are sure that you have seen before; you "know" him in that sense. Such a recognition is usually followed by a search process asking, in effect, Where could I know him from? Who is he? The search process generates likely contexts (Do I know him from work; is he a movie star, a TV commentator, the milkman?). Eventually the search may end with the insight, That's the butcher from the supermarket! (pp [252][253] The initial sense of familiarity reflects strong recognition of the item itself, whereas the subsequent experience of recollection (if it occurs) reflects the retrieval of source information associated with that item. A pure, familiarity-based experience of strong recognition in the absence of source recollection has come to be known as the "butcher-on-the-bus" phenomenon (2-4).An issue of considerable interest is how the structures of the medial temporal lobe support recollection and familiarity. According to one view, recollection depends on the hippocampus, whereas familiarity depends on the adjacent perirhinal cortex (5, 6). Alternatively, it has been proposed that the functional differe...

Impaired capacity for familiarity after hippocampal damage

“…The present findings, together with these earlier results (19), provide evidence that hippocampal lesions impair familiarity as well as recollection. Recollection and familiarity are identifiable psychological constructs that are useful for understanding the nature of recognition memory.…”

“…This same finding has also been obtained in a different way using a source memory procedure (19). Participants studied 25 words; then, in a recognition test, they made confidence judgments ranging from 1 to 6 for 25 old words and 25 new words (1 = definitely new, 6 = definitely old).…”

“…We next examined performance separately for R and K responses when the two kinds of responses were matched for memory strength at a high-confidence level (ratings of [17][18][19][20]. As one might expect, when high-confidence ratings were given, both groups tended to perform rather well.…”

“…For words declared old (ratings of [11][12][13][14][15][16][17][18][19][20], participants then judged whether the word was recollected (Remember), was familiar (Know), or was a guess (Guess). Then, to examine the frequency of R and K responses in each group after removing the effect of memory strength, we compared performance for items endorsed with high confidence (ratings of [17][18][19][20].…”

Memory Retrieval in Mice and Men

“…Whereas many studies report a disproportionate effect of hippocampal damage on recollection and associative memory relative to familiarity (Huppert and Piercy 1978;VarghaKhadem et al 1997;Holdstock et al 2002;Yonelinas et al 2002;Giovanello et al 2003;Mayes et al 2004;Aggleton et al 2005), other reports find that hippocampal damage impacts familiarity and recollection to a similar extent (Manns and Squire 1999;Stark et al 2002;Manns et al 2003;Cipolotti et al 2006;Wais et al 2006;Jeneson et al 2010;Kirwan et al 2010;Song et al 2011). Interestingly, a patient with significant perirhinal damage that spared the hippocampus showed impaired familiarity and preserved recollection (Bowles et al 2007).…”