Some functional properties of iconic storage in retarded and nonretarded subjects.

Four experiments, which examine some functional properties of iconic storage in mildly retarded subjects, are reported. Experiments I and III demonstrated that retardates report about three items, or one item less than normal subjects, after a single brief tachistoscopic exposure and that this span of attention was independent of size of array. Both normal and retarded groups reported more items correctly when arrays were arranged on two lines. Experiment II determined that exposure durations up to 250 msec did not influence the number of items reported by either group. Experiment IV compared the form of decay for both groups by cuing report of each of seven positions at five poststimulus delays. The presence of the typical W-shaped curve for both groups at all delays permitted the inference that items in iconic storage decay together rather than individually. Although quantitative differences existed between groups, in no case did intelligence interact with the manipulated variables. The results were discussed in relation to control processes and structural features within an information processing model of memory.