Correlation between handedness and birth order: compilation of five studies

Area of Science:

• Neuroscience
• Developmental Psychology

Background:

• Theories suggest left-handedness may stem from perinatal hypoxia affecting the left hemisphere.
• Bakan's hypothesis links left-handedness to "high-risk" birth orders.

Purpose of the Study:

• To rigorously test Bakan's hypothesis by pooling data from multiple studies.
• To determine the relationship between birth order and handedness.

Main Methods:

• Meta-analysis of five independent studies investigating birth order and handedness.
• Statistical pooling of data to increase statistical power.

Main Results:

• The pooled analysis revealed a near-zero correlation between birth order and handedness.
• Previous findings supporting Bakan's hypothesis were not replicated.

Conclusions:

• The pooled data do not support Bakan's hypothesis linking left-handedness to "high-risk" birth orders.
• Further research is needed to understand the etiology of left-handedness.