Recency and frequency judgements in alcoholic amnesics and normal people with poor memory.

Alcoholic amnesics have been reported to confuse when an event occurred with how frequently it occurred and conversely, how frequently something took place with when it happened. This lack of independence of recency and frequency judgements, shown by these amnesics (but not shown by normal people) has been interpreted as reflecting a selective amnesic failure in memory for contextual information; this failure, in turn, leading to poor recall and recognition memory. The effect is replicated on another group of Korsakoff patients and, by manipulations of retention intervals and of learning opportunity, it is also shown that normal people with memory that is as poor overall as that of amnesics still have specific contextual memory with which to make temporal judgements independently of frequency of presentation and (somewhat less obviously) frequency judgements independently of recency of presentation. The qualitative differences between amnesic and normal people cannot therefore be an artefact of testing generally poor memory in amnesics. While it is possible that the unavailability or inaccessibility of contextual information may cause amnesia, an alternative hypothesis, that poor contextual knowledge is an incidental feature in alcoholic amnesia (related to frontal lobe dysfunction), is also considered.