Patterns of errors in short-term forgetting in AD and ageing.

This study examined whether the low performance of 40 AD patients in the Brown-Peterson task could be explained by a pattern of errors that differed from 55 elderly controls. Our quantitative results showed that AD patients had a lower performance level in the three retention intervals than controls but a significant interaction between group and interval was not found, indicating that the rate of forgetfulness was similar in the two groups. In our qualitative analysis, errors were categorised as confusions, perseverations, omissions, and order alterations. Contrary to other studies (Dannenbaum, Parkinson, & Inman, 1988; Kopelman, 1985) where an AD forgetfulness tendency of omissions was observed, our data showed an excess of perseveration (even more than five repetitions), indicating problems in the central executive. This could be interpreted in terms of problems in updating the contents of working memory.