Automatic number processing independent of language and notation in bilingual speakers

Numbers are ubiquitous in life. At the same time, the symbols for numbers are highly abstract and their visual appearance does not carry any direct relation to their magnitude. This poses an important question for researchers interested in how numbers are mentally processed. Whereas research on numeric cognition suggests that culturally based number symbols automatically map onto an abstract, semantic representation of magnitude, research on bilingualism suggests that such automatic mapping does not apply to the second language of bilinguals. To address this controversy, I use a masked priming paradigm---the standard tool for investigating automatic cognitive processes---to test whether Spanish/English bilinguals process numbers in the same automatic fashion regardless of language, or differently as a function of the number notations. In two experiments, participants were presented with target numbers and asked to decide whether they were smaller or larger than 5. Unknown to participants, the targets were preceded by rapidly presented numbers, which served as prime stimuli. Participants were faster on congruent prime-target trials (prime and target required the same response) than on incongruent trials (prime and target required different responses). This effect was obtained for bilingual participants and was equally strong across three different notations---Arabic digits, English words, and Spanish words. Further, within congruent trials, the prime facilitation effect increased as the distance between the prime and the target decreased. These effects were obtained even when the primes were presented for 20 ms only (Experiment 2). The findings provide strong evidence for automatic mapping of number symbols to abstract magnitude representations which is independent of language notation.