Feedback and incentive effects on the decrease of interbeat interval.

Johnston and Lethem (1981) have hypothesized that when subjects attempt to decrease their interbeat interval (i.e., increase their heart rate) maximally, then interbeat interval feedback has a purely motivational role, but when they attempt to decrease their interbeat interval by a precise amount, such feedback has a primarily informational role. This was tested by comparing the performance of 16 subjects on both types of task. It was predicted that additional monetary incentives would reduce the difference between feedback and no-feedback conditions when subjects were attempting to reduce interbeat interval maximally but not when attempting to reduce it by a specific amount. This prediction was not supported. Incentive was found to aid performance on the maximal interbeat interval decrease task, but this was independent of the effects of feedback. Only feedback effects were detected on the specific interbeat interval decrease task.