Fine motor performance in subjects of subnormal, normal and superior intelligence. II. Reaction time and warning...

Twenty-four groups of subjects of widely ranging chronological ages (CA: 6-21 years), mental ages (MA: 5-17 years) and IQs (30-130) took part in three reaction time (RT) tasks. These differed only in terms of pre-response complexity, the main differentiating factors being the knowledge of which of four light reaction signals (RSs) would be illuminated (the results of the RS effects have been described by Bankhead & MacKay, 1982) and direction of eye gaze during irregular presentation of three warning intervals (WIs: 1, 3 and 5 s). In the first task ('simple' RT) the subject had to respond to a single light at which he/she looked directly during the WI; in the second ('simple-fixed' RT) the subject fixated a point midway between a horizontal array of four RSs, and had to respond to each one in turn in a series of trial blocks, the subject always being aware of which RS was about to appear; in the third ('complex' RT) the subject had to fixate this same point, and respond to which ever RS came on. (In this last condition, probability of onset varied between RSs, and subjects could try to anticipate which RS was likely to appear in any given trial.) Results showed that: i The 24 groups could be economically considered as representing four different clusters in terms of performance, the best of which involved subjects of relatively high CA and MA, the worst of which comprised severely subnormal subjects (Bankhead & MacKay, 1982). ii While subjects in each of the three most superior clusters tended to show relatively long RTs after the 1-s WIs, the RTs of the poorest cluster were longest after the 5-s WIs. These results were discussed both in terms of task requirement and of attentional deficits among certain of the subjects.