Over a century ago, Yerkes and Dodson (1908) realised that in simple, routine tasks increasing arousal improves performance along an S-curve. However, in complex, nonroutine tasks, performance follows an upside down U-curve.
First, if the arousal increases, performance improves: we stop feeling bored and become more motivated to complete the task. At a certain point, depending on the task and the individual, the rising arousal and individual capabilities reach a balance, and performance peaks. If the arousal still continues to rise, performance starts to decline: we overexert. The finding is robust and applies to both rats – the original subjects of Yerkes and Dodson – and humans (see, for example, an excellent review by Diamond et al. 2007).
Dan Ariely and colleagues have studied monetary reward as a form of arousal and its effect on complex tasks. They found that higher monetary incentives led to worse performance in tasks that required creativity, memory, or motor skills.
The original Yerkes-Dodson curve based on the original evidence from Yerkes and Dodson 1908. The Hebbian version of this curve became popular sometime after the 1950’s. The Hebbian curve left out the top line showing that increased arousal did not adversely impact performance during simple tasks.
By Yerkes and Dodson 1908 [CC0], via Wikimedia Commons.