Whether Jerome Kagan has been pulled or thrown himself full bore into the nature-nurture debate, there is no doubt that his work on babies, children, and the development of temperament has greatly influenced both sides of the discussion. What is in doubt is which side Kagan is on. His views have both been lauded (a 2002 study published in the Review of General Psychology named Kagan as the 22nd most influential psychologist of the 20th century), and criticized for “blowing in the wind.” His early work downplayed the significance of early mother-child interaction in lieu of later life experience, which had before Kagan and his contemporaries, been overestimated. Thus, his initial stance seemed anti-nature. Later work on the incorrigibility of inborn traits seemed to many to endorse the genetic/nature side. Specificially, longitudinal studies done by Kagan and colleagues at Harvard have found that of of all infants 20% demonstrate “high reactive” personalities, and of this 20%, roughly two-thirds develop into shy adolescent children. Lately Kagan has scathingly criticized Judith Rich Harris’s popular dismissal of parental influence on child rearing.
One main reason for the signficance of Kagan’s work is that it has painted some colorful strokes to the canvass that is reality. While everyone seems to want Kagan on their side, Kagan has long seemed more interested in discovering the truth. Perhaps Kagan’s most important contribution is his notion that we seem to inherit a bias toward varied personality dispositions. Like the personalities of dogs, these biases predispose us toward different temperaments – some dogs are naturally friendly, others are naturally aggressive, and many fall at different points along a continuum between friendliness and aggression. Especially significant to Kagan’s notion here is that these biases can be overcome. Under certain environmental influences shy creatures can be “made” more aggressive, while conversely, aggression can be molded into affability. Our inborn temperaments may make this molding more difficult, but not necessarily impossible.
The implications of this often overlooked point abound. Research has already strongly suggested that stuttering is the result of a combination of an inclination (or bias) toward stuttering combined with the right environmental factors. This inclination tugs, but does not guarantee. Other disorders – such as autism – share many etiological similarities. Kagan’s descriptions of high-reactive infants may, after further research, prove particularly enlightening to an accepted description of autism’s complex causes.
A good in-depth (albeit somewhat critical) article was published in the Boston Globe in 2004, and can be accessed here. Much of my information came from a great All in the Mind podcast, which unfortunately is no longer available – although the transcript is here. An excellent post about Kagan’s recent critique of high rates of psychological diagnosis comes from the Smooth Pebbles blog.