The critical role of action in space-number associations: evidence from random number generation.

The influence of space-number associations on action parameters has been widely reported. Yet, some recent studies claim that space-number associations are only the consequence of lateralized actions. However, little is known about the actual influence of action on number representations, and how this influence interacts with the influence of space. Hence, our goal was to further examine the influence of action on number representations, and to characterize the nature of this influence by manipulating both action direction and magnitude. To this end, we used a saccade task followed by a random number generation task (Experiment 1). We show that saccade amplitude shapes number representations, but that this influence depends on saccade direction as it is found for rightward saccades only. Moreover, the influence of target spatial position on the numbers generated vanishes when no action is executed (Experiment 2). In our view, these results demonstrate the critical role of action in space-number associations. We suggest that the influence of space on number representations is only observed through lateralized actions. These findings shed new light on conflicting results in the literature about the influences of space and action, and provide important insights into the mechanisms behind space-number associations.