Word priming during and after transient global amnesia: A case report

Abstract

Many studies have shown relative preservation of word priming in subjects with mild amnesia, but some impairment in severe amnesia. This calls into question the degree of separation between implicit and explicit memory. Possible contamination of implicit memory tasks by impaired explicit memory strategies might be obscuring the actual dissociation between the two memory systems. We have developed a method of circumventing explicit memory contamination by using brief duration repeated primes below the awareness threshold of subjects. We have used this approach to evaluate the status of word priming in a 70-year-old woman with transient global amnesia. This subject was examined during her attack as well as 8 months after. She was tested for word priming on a speeded category membership decision task. Implicit or explicit encoding procedures were used in three different experiments. Results indicated that there was no significant difference between the priming effects measured in the implicit and explicit conditions or between the priming effects measured during and after the transient global amnesia attack. Results also confirmed that brief multiple presentation of words can offer a means of producing word priming in the absence of explicit recognition or recall of the primed words in amnesia. These findings demonstrate that word priming is preserved during transient global amnesia. They also suggest that the capacity to encode, store and retrieve information implicitly, e.g. unintentionally, is retained in this neurological condition.