Right- and left-hand skill: failure of the right shift model

Area of Science:

• Human genetics
• Behavioral genetics
• Psychology

Background:

• Annett's right shift model is a prominent theory explaining the genetics of handedness.
• Skill asymmetry is a complex trait influenced by genetic and environmental factors.
• Previous models have attempted to describe the distribution of handedness and related asymmetries.

Purpose of the Study:

• To evaluate the adequacy of Annett's right shift model for describing skill asymmetry and handedness genetics.
• To introduce and describe a symmetric bimodal model as an alternative explanation.
• To compare the explanatory power of the two models using empirical data.

Main Methods:

• Analysis of existing datasets related to skill asymmetry and handedness.
• Comparative evaluation of Annett's right shift model and a proposed symmetric bimodal model.
• Statistical assessment of model fit to observed data.

Main Results:

• Annett's right shift model provided a less adequate fit to the data compared to the symmetric bimodal model.
• The symmetric bimodal model offered a more intuitive and accurate description of the distribution of skill asymmetry and handedness.
• Empirical data supported the superiority of the symmetric bimodal model.

Conclusions:

• The symmetric bimodal model is a more effective framework for understanding the genetics of handedness and skill asymmetry.
• Annett's right shift model may not fully capture the complexities of handedness distribution.
• Further research should explore the implications of the symmetric bimodal model in human genetics and behavior.