SNARC effects for color decision to non-symbolic representations of quantity

People are generally faster to respond to smaller numbers with a left-sided response and larger numbers with a right-sided response. The SNARC (spatial-numerical association of response codes) effect has been reported for a range of tasks for symbolic representations of number (e.g., digits). However, the evidence for SNARC effects for non-symbolic representations of number (i.e., quantities of objects) is mixed and usually restricted to tasks where numerical properties are relevant. Here, we report six studies where participants made color decisions to circles. We manipulated the stimuli so that displays formed symbolic patterns (i.e., dice-like arrangements, Experiments 1 and 2), canonical but non-symbolic patterns (i.e., symmetrical arrangements, Experiments 3 and 4), or non-symbolic and non-canonical patterns (i.e., scattered arrangements, Experiments 5 and 6). We additionally manipulated whether aggregate surface area was controlled and whether individual elements within displays remained constant in size across the experiment. The SNARC effect was present when (1) circles were arranged in a symbolic manner, or (2) aggregate surface area increased congruently with quantity. The effect of aggregate surface area was not restricted to conditions where individual circles were a consistent size across the different stimuli, suggesting that the visual cue of aggregate surface area was more important than the sense that individual stimulus items were identical across the experiment. Our results are consistent with the view that non-symbolic quantities offer a route to magnitude and its spatial representations, but that this may be modulated by the consistency of high- and low-level visual cues to magnitude.