Bisections in two languages: When number processing, spatial representation, and habitual reading direction interact

Kazandjian, S. 1, 2 , Cavezian, C. 1, 2 , Zivotofsky, A. 3 & Chokron, S. 1, 2

1 ERT TREAT Vision, Laboratoire de Psychologie et NeuroCognition; UMR 5105 CNRS-Université Pierre Mendès France; 1251, avenue Centrale; 38040 Grenoble; France
2 Service de Neurologie, Fondation Ophtalmologique Adolphe de Rothschild; 25 rue Manin; 75019 Paris; France
3 Gonda Brain Research Center, Bar-Ilan University, Ramat-Gan, Israel

In left-to-right reading cultures, a number magnitude continuum places smaller digits on the left and larger digits on the right (Dehaene, Bossini, & Giraux, 1993), thus creating a mental number line, referred to as the Spatial-Numerical Association of Response Code (SNARC) effect. Calabria & Rossetti (2004) demonstrated that the SNARC effect can be seen even when bisecting strings of number words. Strings of smaller magnitude number words were bisected further to the left than strings of larger magnitude number words. The current study investigated whether the left-to-right mental number line associated with number processing will result in similar spatial biases despite a habitual, right-to-left reading direction or among bilingual-bidirectional readers. Monolingual left-to-right readers were compared to bilingual-bidirectional readers of English and Hebrew. Strings of Arabic numerals and of number words (e.g., THREE, EIGHT) were presented in separate conditions in English and Hebrew. Significant rightward bias was seen among native Hebrew readers with a low English reading level compared to English monolinguals. The spatial bias in bisecting either Arabic numeral strings or number words was related to the habitual reading direction of the participant. There was no difference in spatial bias or for frequency of spatial bias based on numerical magnitude for either condition. We discuss the influence of cultural factors, such as reading direction and proficiency, on the representation of spatial and numerical material.