It is widely know that the pattern of human handedness is such that approximately 90% of the population is right handed with the remainder being left handed, at least in the adult population. What is less well understood is how handedness develops and at what age adult-like handedness patterns emerge. Quantified in terms of both preference and performance, a plethora of different behavioral assessments are currently in use with both children and adults. Handedness questionnaires are commonly used; however, these possess inherent limitations, considering their subjective nature. Hand performance measures have also been implemented; however, such tasks appear to measure different components of handedness. In addition to these traditional measures, handedness has been successfully assessed through observation of hand selection in reaching, which has proven to be a unique and effective manner in understanding the development of handedness in children. Research over the past several decades has demonstrated that young children display weak, inconsistent hand preference tendencies and are slower with both hands. Performance differences between the hands are larger for young children, and consistency improves with age. However, there remains some controversy surrounding the age at which hand preference and hand performance abilities can be considered fully developed. The following paper will provide a review of the literature pertaining to hand preference, performance abilities and hand selection in children in an attempt to ascertain the age at which adult-like patterns of hand preference and performance emerge.

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End-state comfort (ESC) is the tendency to assume comfortable postures at the end of simple object manipulation rather than at the start; and therefore has been used to assess the behavioral effects of motor planning. Adult-like patterns have been observed at age 9. Observations can extend to joint-action, such that adults consider the beginning-state comfort (BSC) of another, without sacrificing ESC; however, trends in children have yet to be delineated. This study investigated the development of ESC and BSC in a cup manipulation task. Three to 12-year-olds and adults were asked to pick up a cup and (1) pour a glass of water or (2) pass it to the researcher to pour. Paralleling previous findings, adult-like patterns of ESC were observed at age 9. Adding to the literature, adult-like evidence of BSC emerged at the age of 7. Therefore, 7-year-olds consider another's BSC; however, cannot facilitate ESC until age 9.

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