The effect of combining punishment and reward can transfer to opposite motor learning

Recent laboratory findings have demonstrated that, when imposed separately, punishment and reward have different effects on motor learning. In real-world applications, however, they are usually used in combination to improve human behavior. For instance, a student may be punished when failing an examination and rewarded when getting a high score. It remains unclear precisely how people are motivated when punishment and reward are combined. Moreover, whether it is possible for the effects of punishment and reward to transfer to other learning situations remains unknown. In the present study, four groups of participants were trained on a motor adaptation task under conditions of either punishment, reward, both punishment and reward combination, or a neutral control condition (neither). We tested what the effect of combining punishment and reward is on motor learning and memory. Further, we examined whether the effect could transfer to later opposite-direction learning in the absence of motivational feedback. Specifically, during the initial learning when there is motivational feedback, combining punishment and reward can not only accelerate learning rate, but can also increase learning extent. More interestingly, the effect can even transfer to later opposite-direction learning. The findings suggest that the combination of punishment and reward has a distinct advantage over pure punishment or reward on motor learning and the effect can transfer to opposite motor learning.