Grafting new functions (e.g., reading) onto older brain structures can improve even the skills (e.g., object recognition) for which the old infrastructure had originally evolved

Does Neuronal Recycling Result in Destructive Competition? The Influence of Learning to Read on the Recognition of Faces. Jeroen van Paridon et al. Psychological Science, February 25, 2021. https://doi.org/10.1177/0956797620971652

Abstract: Written language, a human cultural invention, is far too recent a development for dedicated neural infrastructure to have evolved in its service. Newly acquired cultural skills, such as reading, thus recycle evolutionarily older circuits that originally evolved for different, but similar, functions (e.g., visual object recognition). The destructive-competition hypothesis predicts that this neuronal recycling has detrimental behavioral effects on the cognitive functions for which a cortical network originally evolved. In a study with 97 literate, low-literate, and illiterate participants from the same socioeconomic background, we found that even after adjusting for cognitive ability and test-taking familiarity, learning to read was associated with an increase, rather than a decrease, in object-recognition abilities. These results are incompatible with the claim that neuronal recycling results in destructive competition and are consistent with the possibility that learning to read instead fine-tunes general object-recognition mechanisms, a hypothesis that needs further neuroscientific investigation.

Keywords: reading, face perception, literacy, neuroimaging, open data, open materials

Discussion

Our findings are incompatible with destructive competition and consistent with neuroimaging evidence (Hervais-Adelman et al., 2019) that learning to read may fine-tune object-recognition mechanisms, namely, that reading acquisition results in increased sensitivity to visual stimuli in addition to reading-related enhanced attentional and oculomotor capacities (Kastner et al., 2004; Skeide et al., 2017).

Importantly, the comparatively better object-recognition abilities of literates than illiterates appear to be directly related to reading acquisition. Such abilities are very unlikely to be a secondary effect of literacy, such as increased verbal working memory (Demoulin & Kolinsky, 2016; Smalle et al., 2019), general cognitive ability, or familiarity with test taking, because in the present study we regressed out common variance associated with these traits. To more directly assess causality, we recommend further investigation of the results from the present large-scale cross-sectional study with a longitudinal design (cf. Goswami, 2015; Huettig, Lachmann, et al., 2018). The positive relationship between reading ability and object-recognition memory in the present study casts serious doubts on the viability of the destructive-competition hypothesis. Whereas this hypothesis views the brain as a system with finite processing resources for which different functions are competing, the present findings raise the intriguing possibility that the brain, remarkably, is able to support new abilities in such a way that related older abilities can be enhanced rather than impaired. Further behavioral and neuroscientific research could explore this possibility in more detail, for instance, examining whether literates’ better object-recognition abilities are related to shared (neural) processing between face and word reading, as both skills require sophisticated foveal processing.