The Motor Wisdom of the Crowd
Authors: Madirolas Gabriel , Zaghi-Lara Regina , Matic Adam , Gomez-Marin Alex , Pérez-Escudero Alfonso 
Published: February 2022

AbstractWisdom of the Crowd is the aggregation of many individual estimates to obtain a better collective one. This effect has an enormous potential from the social point of view, as it means that a decision may be taken more effectively by vote among a large crowd than by a small minority of experts. Wisdom of the Crowd has been demonstrated in a wide range of cognitive tasks, all of which involve rational thinking. Here we tested this effect in the context of drawing simple geometrical shapes which, while still enacting cognitive processes, mainly involved visuo-motor control. We asked more than 700 school students to trace with their finger a predefined pattern shown on a touchscreen, and analyzed whether their individual trajectories could be aggregated in a way that improved the match with the original pattern. We found that this task has all the characteristics of the strongest examples of Wisdom of the Crowd: First, the aggregate trajectory can be up to 5 times more accurate than the individual ones. Second, this great improvement requires aggregating trajectories from different individuals (rather than different trials from the same individual). Third, the aggregate trajectory outperforms >99% of the individual trajectories. Fourth, when we split our dataset between young children (<10.5 years old) and older children, we find that older individuals outperform younger ones, as naively expected. However, a crowd of young children outperforms the average older individual. In sum, we demonstrate for the first time the Wisdom of the Crowd phenomenon in the realm of motor control, opening the door to further studies of human but also animal behavioral trajectories and their mechanistic underpinnings.Significance statementWisdom of the Crowd is the aggregation of many individual estimates to obtain a better collective one. Thanks to a combination of mathematical, psychological and social factors, this collective estimate can be surprisingly accurate, even when it comes from a crowd of poorly informed individuals. Originally proposed in the context of simple tasks (such as estimating a number), a general version of this concept now pervades our society, from being a key reason behind the success of democracies to being explicitly used to generate collective high-quality knowledge, from Wikipedia to Stack Exchange. Despite this enormous practical success, academic research lags behind, with most studies focusing on simple and narrow tasks. Here we apply the concept for the first time to a sensory-motor task, testing whether the combination of many drawings traced by different subjects resembles the original template. This type of task is wildly different from previous studies of Wisdom of the Crowd, as it depends on continuous sensory-motor control, rather than explicit reasoning or discrete decision-making. We demonstrate that the effect is strong: The aggregate trajectories are more accurate than an overwhelming majority of the individual ones, and a crowd of young children outperforms the average teenager with more mature motor skills.