The multileveled processes underlying behavioral fluctuations in development
Infants’ reaching, and many related manual behaviors such as two-handed coordination, hand preference, object manipulation, and upper arm spontaneous behaviors, do not always develop in a linear fashion over the 1st year of life. Rather, they fluctuate and show multiple regressions before settling into stable, predictable, and adapted responses. Over the past two decades, we have attempted to understand why such fluctuations in early behavior occurred. The traditional view, held since the mid ‘40s, was that these fluctuations occurred because of autonomous reorganization of the neuromotor system. From a dynamic systems perspective, however, such regressions could be taking place as the product of reorganizations and interactions between elements of the behavioral system. In a series of longitudinal studies, we were able to show that these documented developmental regressions occurred during periods when infants developed new motor skills, such as sitting, crawling, or walking. For example, we found that infants’ earlier manual preferred biases temporarily dissipated when they were learning to crawl and that infants regressed to two-handed reaching at the end of the first year when they were learning to walk upright, despite extensive prior experience at reaching at those objects with one hand. Thus, regressions in hand preference and reaching occurred every time infants were faced with new postural challenges and were confronted with new sensory-motor problems to solve. Recently, we were able to show that these fluctuations corresponded to experience dependent brain reorganizations as infants learned to master new forms of locomotion. This recent study highlights again that sensorimotor learning and developmental reorganizations occur at multiple levels.
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- Corbetta, D., Friedman, D. R., & Bell, M. A. (2014). Brain reorganization as a function of walking experience in 12 month-old infants: Implications for the development of manual laterality. Frontiers in Psychology: Cognition, 5:245. doi: 10.3389/fpsyg.2014.00245