Cardiovascular and Skin Conductance Correlates of a Fixed‐Foreperiod Reaction Time Task in Retarded and Nonretarded Youth

Changes in heart rate (HR), digital and cephalic pulse amplitude, and skin conductance were studied during a fixed-foreperiod reaction time (RT) task. Mentally retarded adolescents with a mean mental age of 9 yrs, 10 mos were compared with two nonretarded groups matched on mental age (MA) and chronological age (CA), respectively. AH subjects received 20 RT trials with distractors (music) during the 4-sec preparatory interval (PI) and 20 trials without music in a counterbalanced design. The warning signal was a 1 sec light presentation and the reaction signal was an 82 dB tone. Retarded subjects had longer and more variable RTs than the controls. Retarded subjects had smaller HR accelerations and decelerations during the PI than the CA group but not less than the MA group. Further, the retarded group had a marginally lower tonic skin conductance level, smaller skin conductance responses, and smaller constrictions in cephalic pulse amplitude than the CA controls. The results are discussed in terms of attentional and arousal deficits in retarded persons. Some comments are focused on the developmental findings (MA vs CA groups) and on the discrepancies among the skin conductance and cardiovascular measures.