Working memory in Down syndrome : Training the rehearsal strategy

Verbal short-term memory skills of Down's syndrome subjects are very poor (Hulme & MacKenzie, 1992; Bower & Hayes, 1994). The poster reports on the verbal short-term memory skills in Down syndrome and on the possibility of increasing durably memory span by using a rehearsal training strategy. Three tasks (letters span, digits span and words span) have been presented to two groups of 12 Down's syndrome subjetcs as a pre-test. Each group contained 4 chilren, 4 teenagers and 4 young adults. The groups had similar memory span and mental age at the beginning of the study. None of these subjects seemed to rehearse. One group has been exposed to an intensive rehearsal training during 8 weeks (half an hour / week) (methodology inspired from Hulme & MacKenzie, 1992, and Broadley & MacDonald, 1993). The other group did not receive any training. After the training, the 3 initial memory tasks have been presented to the 2 groups as a post-test. The trained subjects significatively improved their memory span (on the 3 measures and on a global measure) whereas the non-trained subjects did not improve at all. We must notice that the young adults needed a longer training (10 weeks) in order to show a signifiant improvement for the three measures. Only the trained subjects showed, at this time, clear signs of systematic rehearsal. Six weeks after the first post-test a second post-test has been conducted. The trained subjects did not seem to rehearse systematically anymore, their memory performances felt significantly lower than after the first post-test but remained significatively higher than at the beginning of the study