Development of Early Handedness, Manual Specialization, and Hemispheric Specialization
Bibliographic record
Abstract
The development of handedness is related to the development of specialized manual function but follows its own developmental trajectory. Specialized lateralized hand function is referred to as manual specialization and is considered a reflection of underlying hemispheric specialization—for example, in terms of the left hemisphere's superior fine motor and language skills and the right hemisphere's superior spatial skills. The two major models used to explain laterality development concern an early equipotential and then a progressive lateralization of development versus an invariant model—for example, in which the two hemispheres exhibit from early in life the characteristics of adult hemispheric specialization. This entry critically examines the development of handedness, manual specialization, and hemispheric specialization, and, novel to the literature, shows that the equipotential and invariant models are not contradictory. It examines research for both lateralized behavior and brain structure and function from one age period to the next (prenatal to preschool). The research points to connectivity and network models as new ways of explaining left–right differences in brain and behavior, which tie into a proposed activation–inhibition coordination model. The origins of laterality in behavior and brain are shown to lie in biological and environmental influences, including genetically and culturally.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".