A recent study sheds light on why both humans and monkeys may struggle to perform under pressure when high rewards are at stake. Researchers found that stress impacts brain signals essential for executing movements, leading to subpar performance. The study involved three monkeys completing tasks to earn water as a reward. When the reward was moderate, the monkeys excelled. However, when faced with a potential large jackpot, their performance declined significantly. This finding aligns with experiences seen in high-stakes environments, such as competitive sports or performing arts.

Understanding Motor Preparation

The study, which was published in the journal Neuron, tested the monkeys’ speed and accuracy as they reached for a target on a screen. The monkeys had to wait for a cue indicating when to reach, with different cue colours corresponding to varying reward sizes. Before the official trials, the scientists confirmed that the monkeys could identify larger rewards with nearly perfect accuracy.

During the trials, researchers monitored hundreds of neurons in the monkeys’ brains using implanted electrodes, focusing on areas involved in “motor preparation.” Notably, the monkeys exhibited the worst performance when the reward was either too small or excessively large. Adam Smoulder, a doctoral student at Carnegie Mellon University and lead author of the study, noted that the monkeys seemed overly cautious when a big reward was involved, which hindered their speed.

Implications for Human Behaviour

The study suggests that the size of a reward affects whether the brain achieves an “optimal zone” for motor preparation, where performance is maximised. When rewards exceed this optimal point, performance deteriorates. Co-senior author Steven Chase, a biomedical engineering professor at Carnegie Mellon, emphasised the importance of these findings for understanding human behaviour, particularly in contexts like addiction and obsessive-compulsive disorder.

The researchers aim to identify ways to facilitate these optimal neural patterns to improve performance under pressure. Christopher Mesagno, a senior lecturer at Victoria University, highlighted that while this study provides insights into neural pathways, future research could further explore the effects of social anxiety in humans.