Influence of gaze observation on random number generation.

Recent findings suggest that number processing is intimately linked to space and attention orienting processes. For example, processing numbers induces shifts of spatial attention, with small numbers causing leftward shifts and large numbers causing rightward shifts, suggesting that number magnitude might be represented on a left-to-right mental number line. However, whether inducing spatial attention shifts would in turn influence number production, and whether such influence, if observed, would be restricted to the left-to-right orientation or would extend to an up-to-down orientation in space, remains a matter of debate. The present study assessed whether observing gaze movements, known to moderate spatial attention, was able to influence a random number generation task, and how different directions of the gaze moderated this influence. Participants were asked to randomly produce a number between 1 and 10 after they observed either a horizontal or a vertical eye gaze, or after they observed color changes as a control condition. The results revealed that number production was influenced by the prior presentation of specific gaze changes. Observing leftward or downward gaze led participants to produce more small than large numbers, whereas observing gaze oriented rightward and upward or observing color changes did not influence the magnitude of the numbers produced. These results show that the characteristics of the observed gaze changes primed number magnitude, but that this only held true for some movements, and these were not restricted to the left-to-right axis.