The Effects of Monetary Incentive and Frustrative Nonreward on Heart Rate and Electrodermal Activity

Further investigation of a recent theoretical model positing the existence of mutually antagonistic appetitive versus aversive motivational systems was conducted by providing monetary incentives for 3 trials and then either with or without warning terminating the incentives for the last 2 trials. Two dependent measures-heart rate and electrodermal activity–were employed to test the predictions that incentives would activate the appetitive system and produce heart rate acceleration, while unsignalled termination of incentives (frustrative nonreward) would activate the aversive system and produce relative electrodermal activity increases. An additional goal was to investigate the effects on heart rate of different magnitudes of incentive per response unit and varying the amount of work per response unit–two ways of achieving different total amounts per trial. The data showed a clear and graded heart rate response to varying the amount of work per response unit. These results were interpreted as consistent with the conclusion that the heart rate response is a function of the amount of incentive per unit of effort. In contrast to the clear effect on heart rate, the incentive manipulations had no observable effect on electrodermal activity. Conversely, electrodermal activity showed a clear response to frustrative nonreward, while heart rate was not affected. These results were interpreted as consistent with the notion of separate motivational systems mediating different behavioral effects.