Number representation: A question of look? The distance effect in comparison of English and Turkish number words

Cohen Kadosh found that Hebrew number words and Arabic digits elicited different distance effects. The numerical distance effect (i.e., faster reaction times and smaller error rates for numbers with larger distance to a standard number, e.g., 5) was smaller for number words than for digits. The author suggested that the result indicated a notation-dependent (i.e., nonabstract) numerical representation. Alternatively, however, it is possible that the distance effect was decreased by perceptual features of the Hebrew number words used as stimuli. To test this hypothesis, we replicated the study of Cohen Kadosh, but with English and Turkish number words compared to Arabic digits. The perceptual features of Turkish number words lead to the hypothesis that the opposite effect should be present: an increased distance effect for number words compared to Arabic digits. On the other hand, English number words show features similar to those of Hebrew number words, thus leading to the expectation of a decreased distance effect for them. Our results confirmed our hypotheses. We conclude that the distance effect can be influenced also by perceptual features in addition to the impact of numerical representations.