This study aims at investigating the covert behavior of retarded children in a simple reaction time task. For this purpose, several recurring visual stimuli (cues), in varied periodicity, were introduced during a constant warning interval (WI). Under these conditions, it was necessary to clarify two pioblems, i, e., strategies of readiness for response by the cues in retardates, and optimum condition to minimize RT in retardates.
The
Ss consisted of 12 retarded children (mean MA 9: 4, mean IQ 64) and 12 normal children, matched for CA (14 years).
In Exp. I, each S performed RT task with four experimental conditions (non cue, 1 cue, 3 cues, 7 cues) which differ in frequency of cues during the WI of 15 sec. The result indicated that normal children decreased the RT as the frequency decame higher, while such relationship could be shown in retardates at the last 2 trials only. Comparing this result with the RT in control conditions in which the last cue was presented, it was suggested that normal children may have used the strategy of decreasing RT in recognizing the last cue, but retardates may have been unable to use such strategy, the strategy used by retardates being a temporal regularity of the presentation of cues.
In Exp. II, the effect of temporal regularity of the presentation of cues was examined. In this experiment, RT was measured in cues+ verbal stimuli (1, 2, 3,...) conditions, which supported the Ss in recognizing the last cue, and it was compared with the RT in control conditions of Exp. I. Under these two conditions, retardates have shown more marked RT decrease in cues + verbal stimuli conditions, while normals have shown no RT difference between them.
In Exp. III, the effect of temporal regularity of the presentation of cues was further examined. In this experiment, RTs in regular and irregular conditions, differing in temporal order of cue presentation, were compared. As a result, retardates decreased their RT at the process of trials in the regular condition, but such decrease was not shown under irregular condition.
The analysis of these results were summarized as follows.
(1) Normals Used the strategy of decreasing RT in recognizing the last cue, while retardates were unable to do so.
(2) The effect of temporal regularity of the presentation of cues was shown in retardates, but not shown in normal children.
(3) The optimum condition, under which RT in retardates was minimized most, was the condition in which the cues were given in temporaly regular order with added verbal stimuli.
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