Non-symbolic numerosities do not automatically activate spatial-numerical associations: Evidence from the SNARC effect

The SNARC (spatial numerical association of response codes) effect is the finding that people are generally faster to respond to smaller numbers with left-sided responses and larger numbers with right-sided responses. The SNARC effect has been widely reported for responses to symbolic representations of number such as digits. However, there is mixed evidence as to whether it occurs for non-symbolic representations of number, particularly when magnitude is irrelevant to the task. Mitchell et al. (2012) reported a SNARC effect when participants were asked to make orientation decisions to arrays of one-to-nine triangles (pointing upwards versus pointing downwards) and concluded that SNARC effects occur for non-symbolic, non-canonical representations of number. They additionally reported that this effect was stronger in the subitizing range. However, here we report four experiments that do not replicate either of these findings. Participants made upwards / inverted decisions to one-to-nine triangles where total surface area was either controlled across numerosities (Experiments 1, 2 and 4) or increased congruently with numerosity (Experiment 3). There was no evidence of a SNARC effect either across the full range, or within the subset of the subitizing range. The results of Experiment 4 (in which we presented the original stimuli of Mitchell et al.) suggested that visual properties of non-symbolic displays can prompt SNARC-like effects driven by visual cues rather than numerosity. Taken in the context of other recent findings, we argue that non-symbolic representations of number do not offer a direct and automatic route to numerical-spatial associations.