How Does Language Modulate the Association Between Number and Space? A Registered Report of a Cross-cultural Study of the SNARC Effect

Past investigations into the connection between space and numbers have revealed its potential vulnerability to external influences such as cultural factors, including language. This study aims to examine whether language moderates the association between space and number in the spatial- numerical association of response code (SNARC) effect, which is demonstrated in an interaction between number magnitude and response side. The SNARC effect has been observed across various stimuli. However, research on the influence of linguistic factors, such as reading direction, on the SNARC effect has yielded contradictory findings. We systematically examined the moderating effect of language on the SNARC effect in a cross-cultural design. A group of British English speakers and a group of Iranian Farsi speakers performed four SNARC tasks including both explicit (magnitude classification) and implicit (parity judgement) processing of number mangnitude in two modalities of visual and auditory presentations. To the best of our knowledge, this is the first systematic investigation of language, magnitude processing, and sensory modalities altogether. While our registered analyses found no group differences in SNARC tasks, non-registered analyses using a Bayesian ex-Gaussian framework revealed novel findings: a stronger SNARC effect in slower responses and auditory tasks. These findings challenge the idea of a substantial language role in shaping the SNARC effect but also indicate large uncertainty regarding the exact nature of language- induced effects, highlighting the need for further investigations of spatial-numerical interactions that may be differently influenced by linguistic and cultural factors.