TEMPORAL REGULATION OF BEHAVIOR WITH AN EXTERNAL CLOCK IN 3-YEAR-OLD CHILDREN - DIFFERENCES BETWEEN WAITING AND RESPONSE DURATION TASKS

The present study investigates the role of an external clock in two temporal conditioning situations, one which requires spacing the responses of a critical duration (DRL 5 s) and the other producing a response for a set duration (DRRL 5 s). In each schedule, two groups of 3-year-old subjects were administered eight sessions. The external clock was present in the first four sessions for the experimental groups and never present for the control groups. The presence of the clock increased the efficiency of children's performance as compared to the control group in both learning situations. After the suppression of the external information, the experimental subjects' performance was impaired. However, analysis of individual response duration distributions in the DRRD schedule revealed that 3-year-olds continued to regulate their response durations accurately. In contrast, the majority of the subjects failed to adjust their waits to the required delay in the DRL situation. This suggests that in DRL, the external clock played the role of a signal to respond, whereas in DRRD it played the role of an instrument to measure time. (C) 1994 Academic Press, Inc.