Contrast polarity affects verification of addition and subtraction problems via conceptual mapping

The extent to which processing of abstract numerical concepts depends on perceptual representations is still an open question. In four experiments, we examined the association between contrast polarity and mental arithmetic, as well as its possible source. Undergraduate psychology students verified the correctness of single-digit arithmetic problems such as 2 + 5 = 7 or 9 − 6 = 5. Problems appeared either in white or black on a grey background,...