Error rate (M, SD in %) in Experiments 1–4 as a function of key distance (close, far) and Stroop congruency (congruent, incongruent, neutral).

<p>Error rate (M, SD in %) in Experiments 1–4 as a function of key distance (close, far) and Stroop congruency (congruent, incongruent, neutral).</p

Response and stimulus set-ups in the different experiments.

<p>A. Experiments 1 and 3–4, after <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0091432#pone.0091432-Lakens1" target="_blank">[3]</a>: keyboard keys assigned to responses in the close (‘K’, ‘L’) and far (‘S’, ‘5’) distance conditions, respectively. B. Experiment 2: custom-made response keys were not labeled and could be adjusted in distance. C. Experiment 1: instructions about mappings of font colors to response keys were presented in the lower left and right corner of the screen. D. Experiment 4: instructions were presented centrally at the bottom of the screen.</p

Regression coefficients of dRT over number and dRT over magnitude bins.

<p>Regression coefficients of dRT over number and dRT over magnitude bins.</p

Left-handed and right-handed responses to each number in each notation, magnitude judgement.

<p><b>SNARC effect</b>: Right-handed responses slower than left-handed responses for small numbers, faster for large numbers. <b>Distance effect</b>: Increased responses times for numbers closer to the middle. Bottom right: Participants who reported using visual categorisation (per our questionnaire; plotted in grey) vs. those who did not. Note the slightly compressed y-axis in this plot. Error bars indicate within-subject SEMs for each number, pooled across each contrast of numbers [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163897#pone.0163897.ref052" target="_blank">52</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163897#pone.0163897.ref053" target="_blank">53</a>]. Horizontal dashed lines indicate grand means of RTs for each notation.</p

Left-handed and right-handed responses to each number in each notation, parity judgement task.

<p><b>SNARC effect</b>: Right-handed responses slower than left-handed responses for small numbers, faster for large numbers. Error bars indicate within-subject SEMs for each number, pooled across each contrast of numbers [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163897#pone.0163897.ref052" target="_blank">52</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0163897#pone.0163897.ref053" target="_blank">53</a>]. Horizontal dashed lines indicate grand means of RTs for each notation.</p

The stimuli used in our experiments.

<p>(a) Arabic digits, (b) simple-form Chinese characters, (c) Chinese hand signs as used in Chinese Sign Language. Stimuli in each column represent identical numbers. Note that the number 5 is omitted in all notations. This enabled us to use it as the standard for the magnitude judgement task. Hand signs images retrieved from <a href="https://en.wikipedia.org/wiki/Chinese_number_gestures" target="_blank">https://en.wikipedia.org/wiki/Chinese_number_gestures</a>, created by Wikipedia user Ningling, and used under the terms of the GNU Free Documentation License.</p