A recent study sheds light on why both humans and monkeys may have trouble performing under pressure when high rewards are at stake. Researchers have found that stress affects the brain signals necessary to perform movements, leading to poorer performance. The research involved three monkeys performing tasks in order to receive water as a reward. When the reward was moderate, the monkeys excelled. However, when faced with a potential large jackpot, their performance dropped significantly. This finding is consistent with experiences seen in high-stakes settings, such as competitive sports or the performing arts.

Understanding motor preparation

The study, which was published in the journal Neuron, tested the speed and accuracy of monkeys as they reached for a target on a screen. The monkeys had to wait for a cue that indicated when to reach, with different color cues corresponding to different reward sizes. Prior to formal testing, scientists confirmed that monkeys could identify larger rewards with almost perfect accuracy.

During the trial, the researchers monitored hundreds of neurons in the monkey’s brain using implanted electrodes, focusing on areas involved in “motor preparation.” Namely, the monkeys showed the worst performance when the reward was either too small or too large. Adam Smoulder, a doctoral student at Carnegie Mellon University and lead author of the study, noted that the monkeys appeared to be overly cautious when it came to the big reward, which hindered their speed.

Implications for human behavior

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

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