Handedness Development: A Model for Investigating the Development of Hemispheric Specialization and Interhemispheric Coordination

Abstract

The author presents his perspective on the character of science, development, and handedness and relates these to his investigations of the early development of handedness. After presenting some ideas on what hemispheric specialization of function might mean for neural processing and how handedness should be assessed, the neuroscience of control of the arms/hands and interhemispheric communication and coordination are examined for how developmental processes can affect these mechanisms. The author’s work on the development of early handedness is reviewed and placed within a context of cascading events in which different forms of handedness emerge from earlier forms but not in a deterministic manner. This approach supports a continuous rather than categorical distribution of handedness and accounts for the predominance of right-handedness while maintaining a minority of left-handedness. Finally, the relation of the development of handedness to the development of several language and cognitive skills is examined.

Insights Into Human and Nonhuman Primate Handedness From Measuring Both Hands

“…However, this theory is based largely on observations of hand use among adult nonhuman primates and does not consider the individual’s experiences across development. The right panel depicts the cascade theory of handedness (Michel, 2021; Michel et al, 2013), which frames the development of handedness as a series of cascading experiences that start prenatally. Each asymmetrical experience influences the next observed bias.…”

“…As infants gain trunk control, they can support themselves in a sitting posture, which frees up the hands for more complex object manipulation. The hand preference for reaching (measured when reaching is novel and difficult for the infant) predicts the hand preference observed for unimanual manipulation, which in turn predicts the hand preference for RDBM (for a detailed account of the cascade theory of handedness, see Michel, 2021).…”

The interactive functional biases of manual, language and attention systems

“…Performance on the cognitive tasks was measured using reaction time (i.e., averaged bimanual responses) and accuracy (i.e., percentage of correct responses). We calculated a laterality index to express hemispheric asymmetry, for reaction time (LI TIM ) according to (Michel, 2021). Here, a cut-off score of 0.1 was used to categorise individuals with LI values referring to right visual field (LI > + 0.1), left visual field (LI < − 0.1) and non-lateralised (− 0.1 ≤ LI ≤ + 0.1) dominance.…”