Role of finger-based number representations in online arithmetic facts retrieval

Asian people use a symbolic finger counting system, alongside digits, dots, and magnitudes. Even though they may be proficient in a second language, they seem to maintain their own “counting mother tongue” when performing simple maths, for instance, simple addition. For my master’s thesis, I am interested in the interplay between orally delivered arithmetic calculation and visually presented number signs, in either Spanish or Chinese.

Below is a quick summary of my master’s thesis.

There is an increasing number of empirical evidence claiming that internal finger-based number representations affect numerical and arithmetical processing in both children and adults. However, relatively little is known about the online integration between explicit finger-based number representations and verbal number words during calculation. Moreover, because there exist multiple verbal coding types for arithmetic facts as well as more than one finger representations for numbers in bilinguals, it is our aim to identify how bilingual listeners perceive and integrate the bimodal speech-finger information when mathematical problems are orally presented in each language.

In my master’s thesis, I explored the difference in online integration between Chinese monolinguals (use symbolic finger representations only, N = 7) and Chinese-Spanish bilinguals (use both symbolic and iconic finger representations, N = 10). I designed an arithmetical correctness judgment paradigm with multimodal inputs where oral sentences were either arithmetically correct or incorrect and visual finger representations were either in the symbolic form or in the iconic form.

Considering the N400 correctness effect as an index of the successful automatic activation of arithmetic memory networks, data from event-related potentials revealed (1) that in the monolingual group, the N400 correctness effect was only found for the symbolic finger representations; (2) that in the bilingual group, when arithmetic problems were presented in Chinese, there was a marginal N400 correctness effect for symbolic finger representations and a significant N400 correctness effect for iconic finger representations; and (3) that when arithmetic problems were presented in Spanish, N400 correctness effect was found only for iconic finger representations. Furthermore, in the conditions where the N400 correctness effects did not appear, we observed late positive component correctness effects, suggesting a late-time integration after the stimulus onset.

Taken together, these results indicate that symbolic finger representations are tightly attached to Chinese during the access to arithmetic facts in both groups. Meanwhile, iconic finger representations are integrated into both languages in bilinguals, thus serving the arithmetic facts retrieval. This further confirms that once the iconic finger patterns were acquired, they become independent from the linguistic input. All these highlight the crucial role of bilinguals’ language in which they used to learn arithmetic in online multimodal integration. To the best of our knowledge, the present study is the first one that looks at the brain potentials in the context of arithmetic facts retrieval to investigate the online integration between finger-based number representations and verbal number words, therefore provides complementary evidence to the multisensory integration in the context of embodied numerical cognition.