The effects of interference on verbal learning in multiple sclerosis.

Thirty multiple sclerosis (MS) patients were compared with 30 matched (age and education) controls and were asked to learn and recall 20 target words that were placed among 24 distracter words. Targets and distracters were printed on different colored cards, and the subjects were asked to read each word aloud and recall the target words. This task was repeated four times. The MS patients recalled significantly fewer words across the four trials. A second list without distracters was presented for two trials, and there were no significant differences between the groups' recall. Subsequent recall (short delay and long delay) for List 1 revealed significantly poorer recall for the MS group and significantly poorer cued recall but not recognition memory. Retrieval processes were implicated such as source memory, or contextual stamping, rather than encoding mechanisms.