I started my research career in the 1970’s with an emphasis on eye dominance. One of my most influential papers on this topic, as measured by citations, was published in Psychological Bulletin in 1976 (Dominant eye). I soon extended my research efforts to other forms of laterality including handedness, footedness and earedness. I published another influential paper that appeared as a cover story in Science in 1977. This paper analyzed the depiction of left- and right-handedness in works of art (50 centuries). With colleagues, I developed a questionnaire method to assess the four types of laterality, handedness, footedness, eyedness and earedness. This measurement inventory was published in 1979 in The Journal of Clinical and Experimental Neuropsychology (DOI: 10.1080/01688637908401098). We used this questionnaire to measure the four types of laterality in individuals from ages 8 to 80. These data were published in The Journal of Gerontology in 1980 (Age trends). We also measured the similarity of laterality patterns among family members in a paper published in 1980 in Behavior Genetics (Family patterns). In 1981, I co-authored the book, Lateral Preferences and Human Behavior. This book has been cited over 800 times by other researchers over the intervening years. It is still widely cited today (Lateral preferences and human behavior).
In the 1980’s and 1990’s I turned my attention to the question of handedness plasticity. How easy or difficult is it to change one’s handedness from the left to the right hand or the reverse, from the right to the left hand? This interest was prompted by a query from a personal injury lawyer in British Columbia, Canada. He asked me if a person would be permanently disabled by an injury to the preferred hand. Was it possible or impossible to transfer the preferred hand skills to the non-preferred hand? There was little research data on this issue but his question sparked my interest. I began research with physiotherapists who treated clients with hand injuries ranging from mild to severe. I also began to study the prevalence of preferred hand switch attempts among individuals who had not suffered hand injuries. The paper on handedness switches was published in Behavior Genetics in 1986 (Handedness switch). The two papers on hand injuries and related handedness shifts were published in 1993 and 1995 in Neuropsychologia (Hand injury-1) and Behavior Genetics (Hand injury-2), respectively. The 1980’s was a period of controversy over the relationship between birth stress factors and shifts in handedness from the right to the left side. The controversy among researchers was so heated that my colleagues and I tried to shed light on the issue by publishing a review of the existing literature on the topic published in Psychological Bulletin in 1989 (Birth stress).
The 1990’s saw the emergence of another heated controversy about left-handedness. Research was published claiming that left-handers did not live as long as right-handers. The alleged longevity difference was 9 years. This claim made left-handedness a health and mortality risk factor equivalent to heavy smoking. One line of evidence used to support the shorter lifespan of left-handers was the claim that there were few left-handers to be found among adults over the age of 65. As part of the international research effort to investigate the alleged longevity difference between right- and left-handers, I began to study the incidence of both left-handedness and rightward handedness switch attempts among groups of older adults from the ages of 65 to over 90 years. I published a number of papers on these issues in the late 1990’s and into the 2000’s. The most important were published in 1998 and 2000 in Developmental Neuropsychology (Illness) (Switch history) and in 2009 in Laterality (Conversion).
My interest in handedness continued and culminated in the fulfillment of my longstanding ambition to write a book about left-handedness. This book, published in 2016, is titled Laterality: Exploring the Enigma of Left-handedness (Laterality).
