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Document Type

Open Access

Degree Program

Neuroscience & Behavior

Degree Type

Master of Science (M.S.)

Year Degree Awarded

January 2007

Month Degree Awarded

September

Keywords

handedness, laterality, infants, hand preference, hand performance

Abstract

Lateral biases are evident in a number of behaviors across many organisms. The present work was concerned with the particular lateral phenomenon known as handedness. Previous research has suggested that handedness is not a one-dimensional trait. This study evaluated handedness using two factors: hand preference and hand performance. Hand preference refers to the hand chosen to carry out a given action whereas hand performance refers to each hand’s ability, or skill, at carrying out that action. The relationship between hand preference and hand performance has been studied extensively in adults, but the larger body of work with human infants has only assessed hand preference. The goals of this study were to develop a methodology to measure infant hand performance and to begin to examine the relationship between hand preference and hand performance in development. To this end, thirty-six 11-month-old infants were videotaped completing three tasks. The first task assessed hand preference and consisted of a free-play period during which infants were presented with a series of toys that afforded different types of manipulation. The second and third tasks were novel measures of infant hand performance. The second task assessed the infant’s gross motor skills and involved fitting a ball into the top aperture of a toy. The third task assessed the infant’s fine motor skills by requiring infants to retrieve a Cheerio from a stationary plastic cup. Overall, the majority of infants were found to be right-preferent. This was in agreement with previous studies of hand preference in 11-month-olds as well as the pattern of hand preference seen in adults. There was no group-level asymmetry on either measure of hand performance. Hand preference was regressed on hand performance in an overall model of handedness. The right hand’s performance on each task significantly predicted hand preference scores. This was the first study to demonstrate that hand preference can be predicted by hand performance in infants. Future work will examine infant hand proficiency in greater detail as well as the relationship between hand preference and hand performance in nonhuman primate infants.

First Advisor

Neil E Berthier

Second Advisor

Melinda A. Novak

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