Korsakoff amnesics are poor at judging the sequence of two tones

Alcoholic amnesics were given a test of temporal sequencing ability devised by Efron which has practically no memory component. These amnesics were very impaired on the task. However, the extent of this impairment did not relate to the magnitude of their ‘target’ memory deficit nor did it relate to the ability to make temporal judgments from memory. Two other groups of amnesics (3 post-encephalitics and 4 with ruptured aneurysms of the anterior communicating artery) did not show impairments on the sequencing task. Data from the amnesic patient N.A. (who was unimpaired on the task), three other amnesics (who showed a tendency to be poor at the task) and two frontally damaged patients (one of whom performed especially badly on the sequencing task but had no obvious memory difficulties) were also presented. It is argued that deficits in temporal discrimination may not be found in all amnesics but, when they are observed, are an incidental feature related to additional (possibly frontal) cortical damage. Implications of the results for the view that amnesia results from a deficit in the use of contextual information (including temporal information) are considered.