Human handedness has been the subject of systematic study since 1646, but there is no agreement among researchers as to who can be considered a left-hander, what is the etiology of left-handedness, or what the proportion of left-handedness is in the world's population. This article reports the results of a handedness survey administered to 12,000 subjects in 17 countries, the largest handedness survey attempted. The paper discusses methods for determining handedness, the probability of a genetic component for handedness, and the relationship of sex, birth order, multiple birth, and first-degree relative's handedness on subject's handedness. A hypothesis for the etiology of left-handedness is presented.

The present study examined the effects of culture, age, and sex on three measures of handedness: writing hand, Annett's primary handedness items, and a measure based on hand preference for 11 activities. Using data from a large international study, the relationship between the culture in which participants learned to write (as defined by Hofstede's cultural dimensions) and adult handedness was examined. Participants who learned to write in formal cultures were less likely to be classified as left-handed than those who learned in less formal cultures. Older participants and those who learned to write in formal cultures were more likely to be classified as left-handed by the Annett and 11 item measures than by the writing hand classification. Across measures females were less likely to be classified as left-handed than males. Handedness for writing was found to be more sensitive to cultural influences than the other measures. These results suggest that some measures of handedness may be more sensitive to specific handedness aetiologies than others.

This paper presents a brief overview of the past and current state of handedness research illustrating some of the controversies. It emphasizes two aspects: the lack of agreement on the behavior that indicates to which hand-use group (left or right) an individual belongs, and the reasons for preferring one hand rather than the other for various manual activities.

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In the past twenty years Pet Facilitated Therapy (PFT) has been used, apparently successfully, with several populations, including nursing home residents. Studies report positive behavior changes as a result of PFT intervention, but little effort has been made to quantify such behavior changes. This study presents the results of a PFT program in a nursing home setting. Results were positive, and were measured using the Patient Social Behavior Scale, designed for this study. Nursing home residents showed an increase of social behaviors from pretest to midpoint and from midpoint to post test, but these behaviors declined four weeks after post test. Although both males and females showed an increase in social behaviors, males' and females' response patterns differed.