Order of nominal conjuncts in visual scene description depends on language

Previous work has found that experience with the directionality of a writing system (e.g., left-to-right in English, right-to-left in Hebrew) can affect constituent ordering during spoken language production. Specifically, this work found that speakers of languages with left-to-right writing systems exhibit the same directionality bias in the sequential mentioning of objects when describing pictures with multiple objects. This tendency has been considered a general neuropsychological property (e.g., due to the order in which we scan visual scenes based on experience with particular writing systems). We present evidence inconsistent with this view. Two picture description experiments examined a highly bilingual population of speakers of Spanish and Yucatec Maya in Mexico. These speakers are literate in Spanish (left-to-right), but less so or non-literate in Yucatec (also left-to-right). When speaking Spanish (Experiment 1), participants exhibited a significant left-to-right bias, consistent with the neuropsychological hypothesis. However, when speaking Yucatec (Experiment 2), no such bias was observed. This suggests that the effects of writing systems on speech production are specific to the language associated with the writing system and thus not a general neuropsychological property. In addition, we discuss the potential influence of language-specific frames of reference, and their interaction with literacy, on directional cognitive biases.