In Defense of Qualitative Changes in Development
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In Defense of Qualitative Changes in Development The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Citation Kagan, Jerome. 2008. “In Defense of Qualitative Changes in Development.” Child Development 79 (6): 1606–24. https:// doi.org/10.1111/j.1467-8624.2008.01211.x. Citable link http://nrs.harvard.edu/urn-3:HUL.InstRepos:37964397 Terms of Use This article was downloaded from Harvard University’s DASH repository, and is made available under the terms and conditions applicable to Other Posted Material, as set forth at http:// nrs.harvard.edu/urn-3:HUL.InstRepos:dash.current.terms-of- use#LAA Child Development, November/December 2008, Volume 79, Number 6, Pages 1606 – 1624 In Defense of Qualitative Changes in Development Jerome Kagan Harvard University The balance between the preservation of early cognitive functions and serious transformations on these functions shifts across time. Piaget’s writings, which favored transformations, are being replaced by writings that emphasize continuities between select cognitive functions of infants and older children. The claim that young infants possess elements present in the older child’s concepts of number, physical impossibility, and object permanence is vulnerable to criticism because the inferences are based primarily on the single measure of change in looking time. It is suggested that investigators use unique constructs to describe phenomena observed in young infants that appear, on the surface, to resemble the psychological competences observed during later developmental stages. The primary goal of scientists working in varied allel in the motor profiles of the developing embryo disciplines is to explain how a phenomenon of (Hamburger, 1975). On the other hand, many struc- interest developed its observed form. A central theo- tures and functions of the embryo’s heart and mouth, retical issue in this search centers on the degree to once they appear, are preserved indefinitely. which the current event contains some features that The balance between transformation and preser- were present earlier and contribute to the contempo- vation, which has always been a seminal node of rary observation. Darwin’s great insight was to rec- controversy among developmental psychologists, has ognize that many of the anatomical features and shifted over time as a function of new technologies, functions of mammals were either absent or assumed discoveries in allied disciplines, the need to replace a very different pattern in the organisms that lived a flawed theoretical view, and always the intellectual millions of years earlier from which they presumably climate. Many social scientists had attributed the evolved. For example, the convoluted cortex of hu- differences in academic achievement between the mans is not present in fish, and although the three children of early 20th-century European immigrants bones of the human middle ear are derivatives of a set to America and those of more affluent, indigenous of bones in the fish jaw, they have a qualitatively families to the preservation of early habits and skills different structure and function in the two species. acquired within the family. A 1914 government pam- Thus, it is correct to say that the bones of the fish jaw phlet for mothers contained a warning that, although preceded the bones of the middle ear but incorrect to it rested on little evidence, reified the conviction that declare that the functions and features of the former first impressions can have profound influences on the structure contribute to human hearing. future: ‘‘The first nervous impulses which pass The principle that some elements are preserved through the baby’s eyes, ears, finger, or mouth to the and others are transformed or lost applies to devel- tender brain make a pathway for itself; the next opmental stages within a species. On the one hand, time another impulse travels over the same path, it the glial cells of the young embryo that guide newly deepens the impression of the first’’ (West, 1914, p. 59). created neurons to various cortical layers disappear This belief in the preservation of the products of once the mature neurons arrive at their final destina- early experiences, which was central to behaviorism tion (Rakic, 1995), and the motility patterns of newly and psychoanalytic theory, thrived for over 50 years. hatched birds pecking at the ground have no par- However, the emergence of a new point of view was inevitable when the accumulated evidence failed to support strong versions of this hypothesis. Ethologists, I thank Richard Aslin, Susan Carey,Leslie Cohen, Marshall Haith, especially Lorenz (1958) and Tinbergen (1951), who David Moore, Charles A. Nelson, Nora Newcombe, J. Steven anticipated the ascent of biological mechanisms, re- Reznick, and Jay Schulkin for comments on an early draft. The cruited interest to the biologically prepared compe- incentive for this article was a dinner conversation with Michael Lewis at the 2007 meeting of Society for Research in Child tences of young organisms that might be components Development in Boston. Correspondence concerning this article should be addressed to Jerome Kagan, Department of Psychology, Harvard University, # 2008, Copyright the Author(s) Cambridge, MA 02138. Electronic mail may be sent to jk@wjh. Journal Compilation # 2008, Society for Research in Child Development, Inc. harvard.edu. All rights reserved. 0009-3920/2008/7906-0003 Qualitative Changes in Development 1607 of later functioning. Most new scientific ideas require tudes of the correlations between the Bayley scores between 40 and 50 years before they become popular at 3 or 8 months and the IQ scores of older children bases for inquiry. By the late 1990s, technical reports are minimal (McCall, Eichorn, & Hogarty, 1977); describing biologically prepared conceptual functions hence, the infant competences should be given a in young infants that shared features with those of different name. older children began to fill journal pages (Baillargeon, The uncritical use of the same semantic term to 1994; Dehaene, 1997; Saxe & Carey, 2006; Spelke, 1994; name early and later behavioral profiles that are Spelke & Kinzler, 2007; Wynn, 1992). phenotypically distinct and that might rest on differ- When understanding of a prolonged developmen- ent foundations may tempt less sophisticated readers tal cascade is lean, and it is difficult to imagine the to assume that the two phenomena are exemplars of intervening stages, there is a strong temptation to the same process. These readers should appreciate assume the smallest possible number of transforma- that current evidence has not yet proven with cer- tions between early and later phenomena in order tainty that any representation, emotion, or cognitive to be loyal to the principle of parsimony. That is competence present in healthy 6-month-olds is con- one reason why the 18th-century preformationists tained in the psychological functions of older chil- assumed that a miniature infant was present in the dren. The mind possesses a small number of stubborn newly fertilized egg and why Havelock Ellis per- biases that color the initial perception of events and ceived a link between the look of satisfaction on the the conception of the hidden structures and functions face of a nursing infant and the facial expression of that lie beneath what is observed. One of the most lovers lost in the ecstasy of their sexual caresses (Ellis, profound biases, which children honor, is that ‘‘things’’ 1900). Our fragile understanding of the degree to possess an essence that is unchanging despite surface which the behavioral, cognitive, and emotional fea- malleability. Although young infants possess some tures of the young infant participate in more mature sensory, perceptual, and motor abilities that are pre- forms tempts theorists to assume that the early served indefinitely (e.g., the detection of sweet tastes representations and functions are both necessary for, and sounds and an automatic orienting of the eyes and contain some features of, those that characterize and head to a moving stimulus), some scholars have the psychology of school-aged children. posited cognitive competences that go beyond these However, the habit of applying the same constructs talents to include functions that are more seriously to explain early and later performances, based on symbolic or conceptual in nature (Baillargeon, 1994; presumed similarities between the bases for early and Spelke, 1994; Wynn, 1998). This claim deserves careful later behaviors, does not guarantee that the initial and analysis because, if valid, it has the potential to alter later forms were mediated by the same mechanism. our understanding of the infant and development in The presence of a reliable smile to an approaching a radical way. adult, which usually emerges between 3 and 5 This issue assumes two major forms in contempo- months, reflects the fact that the infant is now able rary research: the preservation of early emotional to assimilate the person’s features to their schemata attachments to caretakers and the preservation of for the adults with whom they interact regularly. It is early cognitive functions. Discussion of the former unlikely that this mechanism is the reason why an has been substantial (Kagan, 1981). Hence, this article adolescent smiles upon greeting a close friend. Two- discusses only the latter issue and continues a critique week-olds and 2-year-olds are likely to protrude their initiated by others (Bogartz, Shinskey, & Schilling, tongue following the same act by an adult (Meltzoff & 2000; Bogartz, Shinskey, & Speaker, 1997; Cashon & Moore, 1977), but young infants also protrude their Cohen, 2000; Cohen & Cashon, 2006; Haith, 1998; tongue to a slim pencil approaching their mouth Haith & Benson, 1998; Mandler, 2004). because infants use their tongue to explore objects The nub of the controversy centers on how much close to their faces (Jacobson, 1979; Jones, 1996; (or how little) transformation of the infant’s psycho- Nakagawa, Sukigara, & Benga, 2003). Hence, if the logical structures occurs as the child grows.