Visual recognition memory in specific learning-disabled children.

BACKGROUND

Reading depends on the efficient storage and retrieval of visual and verbal information. Some studies have shown deficits of specific learning-disabled children in the recall and recognition of visual stimuli. This deficit is usually interpreted to be secondary to a verbal labelling deficiency. In this experiment, we presented serial lists of complex geometric stimuli to a group of specific learning-disabled children (LD) and a non-disabled control group (NLD) at both the elementary and secondary school levels. We hypothesized that the NLD visual recognition performance would be superior to that of the LD group at the elementary school level, but not at the secondary school level. We further hypothesized that the difference was related to inefficient primary visual rehearsal strategies.

METHODS

20 elementary school children (11 LD and 9 NLD) and 31 secondary school children (15 LD and 16 NLD) were presented serial lists of four geometric figures. A probe was presented after a 1 second delay. The subjects pressed a key if the probe was in the list ("same" response) or another key if the probe was not in the list ("different" response). Type of response (correct or incorrect) and reaction time was measured at each serial position for "same" and "different" responses.

RESULTS

At the elementary school level, there was a significant visual recognition memory advantage of the NLD group over the LD group (F(1,8) = 6.83, p = 0.018), but there was no significant difference between these groups at the secondary school level. There was no significant difference in the reaction time between the groups at either of the two levels.

CONCLUSIONS

LD children have poorer visual recognition memory performance than NLD children for complex geometric patterns. Since there was no difference in reaction time between the two groups, attentional or encoding deficits can not adequately explain the recognition memory differences. The results can best be explained by inefficient visual rehearsal strategies with a small pool of visual items that are unfamiliar and difficult to code verbally. The serial recognition task can be used effectively by the optometrist to discriminate the performance of LD and NLD children.