Numerical value is long known to be associated with a variety of magnitude representations, such as size, time and space. The present study focused on the interactive relations of numerical magnitude with a spatial factor which is dominant in everyday vision and is often overlooked, namely, egocentric distance, or depth. We hypothesized that digits denoting large magnitudes are associated with large perceived distances, and vice versa. While the relations of numerical value and size have been long documented, effects of egocentric distance on numeral perception have been scarcely investigated, presumably due to the difficulty to disentangle size and depth factors within three-dimensional visual displays. The current study aimed to assess the potential linkage between egocentric distance and number magnitude, while neutralizing any perceived and/or physical size parameters of target digits. In Experiment 1, participants conducted a numeral size-classification task ('bigger or smaller than 5'), to which they responded with a near-to-body or a far-from-body key. Results revealed shorter responses for small than for large numbers when responded with a key positioned close to the body, and for large than small numbers when responded with a key positioned far from the body (regardless of hand-key mapping). Experiment 2 used verbal stimuli denoting near/remote concepts as irrelevant primes to target digits, further demonstrating a priming effect of conceived distance on numerical value processing. Collectively, our results suggest that distance magnitudes are associatively linked to numerical magnitudes and may affect digit processing independently of the effects of visual size.
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© 2017 Gronau et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.