Perspectives on Psychological Science 6(2) 107–113 ª The Author(s) 2011 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/1745691611400205 http://pps.sagepub.com
Three Lessons Learned Jerome Kagan Department of Psychology, Harvard University, Cambridge, MA
Abstract In this article, I describe varied observations from the past 60 years that motivated three significant changes in the assumptions I held as a young psychologist interested in the development of children. Aspects of these early assumptions penetrate a great deal of current research. The new beliefs are (a) a greater willingness to base concepts on patterns of measurements rather than single independent or dependent variables, (b) learning to include the physical features of the observational setting, including the procedure that generated the evidence, as well as the participants’ gender, social class, and cultural background, as part of the concept, and (c) remaining aware of the possibility that the relations among continuous variables can change as a function of brain maturation during the early stages of childhood. Keywords child development, scientific methodology
Close to 60 years of reflection on experimental observations in laboratories and naturalistic observations in homes, schools, playgrounds, and backyards have forced me to revise a number of assumptions I held on that warm day in 1954 when I received my Ph.D. This article describes three significant changes in my earlier beliefs about the development of cognitive competences, morality, and the balance between experience and biology in creating psychological variation among children. The new beliefs had their origins in collaborative research with many students and colleagues and, fortunately, find support in the empirical work of others. One belief calls for basing a larger number of constructs on patterns of causal conditions and outcomes rather than on the relation between one incentive and one dependent variable. A second belief is that the setting of the observation, as well as the gender, social class, and cultural background of the participants, often limit the generality of an inferred construct. The third new belief recognizes that the relations among measurements are often a function of the child’s maturational stage, especially during the opening years of development. The editor requested that the arguments in this article be based primarily on work from my laboratory. Hence, the frequent references to the research of my students and colleagues should not be interpreted as a narcissistic indifference to the significant efforts of many psychologists who have made the same claims, often with better evidence and more coherent prose.
Look For Patterns Most—I am tempted to say all—of the phenomena psychologists study can result from more than one set of conditions, whether the observations refer to motor behaviors, verbal reports, or biological processes. This implies that the probability of discovering robust relations between a class of incentive and a category of outcome will be enhanced by looking for patterns of measures, rather than focusing on single, usually continuous, variables.
Infant temperaments Persuasive support for the significance of patterns is found in research on high and low reactive infant temperaments. Initially, my students and I had affirmed the variation in the frequency of avoidant reactions to unfamiliar situations or people among 2-year-old children. We called the consistently shy, avoidant 2-year olds inhibited to the unfamiliar and the sociable, bold children uninhibited. It seemed useful to search for the infant behaviors that might predict these two behavioral categories in older children (Kagan, 1994). We filmed the behaviors of more than 450 4-month-old, middle-class, Caucasian infants to nonthreatening, but unfamiliar, visual, auditory, and olfactory events. About 20% of the Corresponding Author: Jerome Kagan, Department of Psychology, Harvard University, 33 Kirkland St., Cambridge, MA 02138 E-mail: [email protected]
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infants combined vigorous limb activity, arching of the back, and frequent crying to these incentives, and we labeled these infants high reactive. In addition, 40% showed the complementary pattern of minimal motor activity, few arches of the back, and little crying, but occasional smiling and babbling, and we labeled these infants low reactive. Two other groups were characterized either by vigorous motor activity with little crying or minimal motor activity with frequent crying. We could have created a continuous variable of arousal to novelty and given each infant a score based on the average of the standardized values for motor activity, arching, crying, smiling, and vocalizing. However, we created high and low reactive categories based only on combinations of motor activity and crying because we believed that these two types of infants varied in the excitability of the amygdala. The work of neurobiologists indicated that an activated amygdala could mediate limb activity, arching of the back, and crying, but it was less obvious that an excitable amygdala mediated the more pleasant affect states reflected in babbling and smiling (Adamec, 1991). That decision turned out to be fruitful. Longitudinal observations of these infants revealed that the behavioral and biological features of the high and low reactives remained different from age 1 to 18 (Kagan, 1994; Kagan & Snidman, 2004; Kagan, Snidman, Kahn, & Towsley, 2007). One of five high reactives (20%), but not one low reactive, combined high levels of avoidance to unfamiliar events in the 2nd year with minimal talking with an examiner, a large brain stem evoked potential from the inferior colliculus to click sounds, and a large event related waveform in frontal sites to discrepant visual scenes at 11 years of age. By contrast, one of four low reactives (25%), but not one high reactive, at age 11 combined high vagal tone in the cardiovascular system, low systolic blood pressure, greater EEG activation in the left rather than right frontal lobe, a small brain stem evoked potential to the click sounds, and a small event related waveform to the discrepant scenes (Kagan & Snidman, 2004). Carl Schwartz assessed 135 of these youths at age 18 using MRI technology. The high reactives had significantly thicker values in a small area in the right ventromedial cortex. This area projects to the amygdala and the central gray. The latter site mediates arching of the back, which was so frequent among high reactive infants at 4 months of age (Schwartz et al., 2010). High reactive adolescents are at a higher risk for developing social phobia than low reactives, but not all social phobics were high reactive infants. Therefore, clinicians and investigators would profit from trying to determine which patients with social phobia began life with a temperamental bias and which developed their symptoms as a sole result of experience. Had we given each infant a score on a continuous index of arousal, none of these predictive relations would have emerged. A taxonic analysis of the infant data by Woodward, Lenzenweger, Kagan, Snidman, and Arcus (2000) and Loken’s (2001) latent class analysis of the more extensive evidence gathered from 4 months to 7 years of age affirmed the wisdom of our decision to create categories of infants based on patterns of behaviors. In
addition, Fox, Henderson, Rubin, Calkins, and Schmidt (2001) have replicated some of these results and confirmed the utility of basing the classification of these two infant temperamental biases on patterns of motor activity and crying. Hinde (1998) provided a persuasive example of the utility of searching for patterns when there are nonlinear relations among measures. A group of 4-year-olds were observed in a preschool setting and also with their mothers at home. Mothers who combined moderate levels of warmth and control, rather than low or high levels, had children who displayed very low levels of aggression. This relation would not have emerged if Hinde had treated the three critical variables as continua and computed correlations among them.
Newborn responsiveness to sounds Almost 40 years ago, a graduate student in Harvard wanted to discover which features of sound would alert newborn infants. He recorded the behaviors of 2-day-old infants to 27 sounds, each sound composed of one of three frequencies, one of three loudness levels, and one of three rise times. After spending several years gathering and analyzing the data with an analysis of variance, he discovered that no particular pitch, loudness, or rise time had a special influence on the infants’ behavior. Frustrated, and in need of advice, I suggested that he look for the one or two stimuli that produced the most obvious signs of alerting in a majority of newborns. After implementing this analysis, he discovered one pattern that fit this criterion. This stimulus, which combined one particular pitch, loudness, and rise time, bore the closest resemblance to the human voice (Kearsley, 1973).
Patterns of verbal reports and behavior The suggestion to base more concepts on patterns of evidence implies that sole reliance on verbal reports, whether from informants or those familiar with them, should be supplemented with behavioral and/or biological measurements, because the same verbal description of a psychological state can originate in different life histories and be accompanied by different brain and psychological states. There are many reasons for this claim. First, individuals vary in their networks of representations of past feelings and images that are linked to the words. No person has conscious access to these implicit knowledge networks or their brain states, each of which can affect their verbal replies. Second, most children and adults are reluctant to admit to actions, traits, or feelings that might be embarrassing or provoke a critical appraisal from the examiner. A shy, avoidant personality is more acceptable in Japan than in the Netherlands. Thus, it is not surprising that Japanese college students reported much higher levels of social anxiety than Dutch students (Schreier et al., 2010). Most important, the correlations between what people say about themselves, or what others say, and their actual traits or actions are usually small (Di Bartolo & Grills, 2006; Riggio
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& Riggio, 2002). The mothers’ descriptions of shyness and timidity in the 11-year-old high and low reactives were not significantly correlated with the child’s past or present behavior. However, when we combined these descriptions with the child’s behavior in the laboratory, we were able to differentiate the high and low reactives (Kagan & Snidman, 2004). Filmed interviews of these youths when they were 15 years old provide a clear example of the mismatch between what people say and their actual behavior. A number of high reactive adolescents told the interviewer that they were neither shy nor anxious with strangers. But these adolescents frequently looked away from the interviewer, and a few never looked directly at her during the 3-hr interview in their homes. By contrast, not one low reactive adolescent who denied being shy shifted their gaze from the interviewer’s face (Kagan, Snidman, Kahn, & Towsley, 2007). Thus, the addition of behavioral observations to the verbal reports permitted us to distinguish between two groups of adolescents who gave exactly the same verbal description of this personality trait. The potential mismatch between what adults say about their past and what objective observations would reveal has special relevance for investigators who attribute current psychological problems to the occurrence of past stressors, when the evidence for the latter comes only from the adults’ fallible recall of their childhoods. Some individuals possess a brain chemistry that leads them to exaggerate the distress accompanying rejection, abuse, or bullying in the past; others have a chemistry that leads them to minimize the level of distress experienced to the same stressor (Patten, 2010; Raczka et al., in press). Thus, variation in verbal descriptions of past stressful experiences becomes a phenomenon to understand rather than the obvious cause of contemporary problems. I suspect that psychologists know that political candidates, seducers, and salespersons say things they do not believe. It is difficult, therefore, to understand why many investigators who rely only on verbal reports assume that a stranger’s answers to their questions are by and large truthful and accurate.
Statistics and patterns The decision to base concepts either on continuous measurements of one variable or on patterns of measures should be determined by a priori, theoretical hunches. A majority of psychologists prefer concepts based on quantitative differences in single continuous measurements because of the statistical techniques they were taught and the demands of reviewers, rather than theory. The problem is that correlations and analyses of variance or covariance were not designed to be especially sensitive detectors of patterns that involve nonlinear relations among the measures—recall Kearsley’s work with newborns and Hinde’s study of children. Until statisticians invent better methods to detect patterns, psychologists will rely on regression and covariance to control for conditions they want to believe are not a necessary element in a causal cascade in which one particular condition of interest leads to some outcome.
For example, psychologists typically rely on covariance techniques to prove that one condition, say abuse, daycare, or bullying during childhood, makes a significant contribution to an outcome that is correlated with the participants’ social class by statistically controlling for the effects of social class. However, this strategy can sometimes lead to the misleading conclusion that the single condition had a causal influence that did not require it being part of a larger pattern that included the social class of the participants. Imagine a scientist who was convinced that a cold temperature made a significant, independent contribution to yearly snowfall levels. This investigator used covariance to control for the influence of relative humidity and would probably find that cold temperatures did account for a small but significant amount of the variation in snowfall. But that conclusion is flawed because snow only falls when both conditions are present. Magnusson and Torestad (1993) appreciate the importance of patterns: ‘‘Pattern description is the first step to an understanding and explanation of the lawfulness of individual functioning. Its main merit ... is that it considers the holistic character of the function of subsystems’’ (p. 445).
The Context and Generality All scientists hope that the concept they invented to explain a new phenomenon is not restricted to the context in which the observations were gathered. Although physicists have been successful at imagining concepts that apply across an extraordinary range of situations, psychologists have found it more difficult to infer concepts that apply to settings very different from the ones that gave rise to the evidence. One reason for this frustration is an inadequate understanding of the fundamental mechanisms mediating the phenomenon. Although biologists agree that DNA strings are the foundations of the protein content of all cells, psychologists are not yet close to an accord on the basic elements or processes that underlie actions, beliefs, or emotions. Hence, they disagree on the defining properties of many popular concepts, including memory, emotion, regulation, morality, stress, and reward. For that reason, the generality of a concept is often restricted to a particular class of context. The term context has both a narrow and a broad definition. The former refers to the physical and social features of the setting, especially its familiarity, the presence of others, and the procedure that produced a specific class of evidence. Variation in these features often affects the outcome. For example, 3-month-old infants display behaviors indicating that they are able to discriminate between a heavy and a light object, as they will hold the lighter object for a longer time. However, this ability is only observed when the infants are tested in a dark room and does not occur when the room is fully illuminated (Striano & Bushnell, 2005). The probability that one bonobo chimpanzee will dominate another depends on whether only two chimps are interacting or a third animal is present (Vervaecke, De Vries, & Van Elsacker, 1999).
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A broad definition of context, which applies primarily but not exclusively to humans who interpret the symbolic meaning of a setting, include the participant’s gender, ethnicity, developmental stage, social class, and cultural background. Because the subjective construal of a measurement context varies with these symbolic categories, psychologists should be concerned by the fact that most of the world’s research on humans is conducted in English by Americans on Americans, often college students with a European pedigree (Arnett, 2008; see Henrich, Heine, & Norenzayan, 2010, for a similar argument).
Ethnicity and class A person’s social class exerts a significant influence on a host of behaviors because class of rearing is associated with distinctive experiences in home and school, an identification with a privileged or less privileged group, an awareness of the differences in potency between self and others, and the biological response to particular challenges (Lahti et al., 2006; Manuck, Flory, Ferrell, & Muldoon, 2004). The robust correlations among adults in developed nations between social class and IQ scores, academic grades, vocation, anxiety and depressive disorders, health, divorce, and antisocial behavior cannot be attributed only to genes (Adler et al., 1994; Schiff et al., 1978; Simm & Nath, 2004). The combined influence of class and ethnicity was apparent in a study of the likelihood of a suicide attempt by residents of Sweden. To predict this rare action, the investigators had to examine both the person’s national origin and social class. Lower class women who had been born in Finland and upper-middle-class women born in East Asia had the highest suicide risk (Westman, Hasselstrom, Johannson, & Sundquist, 2003). The influence of ethnicity was revealed in the different reactions 4-month-old Caucasian infants from Boston or Dublin and Chinese infants from Beijing displayed to the episodes used to categorize infants as high or low reactive. Recall that a combination of high motor activity and crying, characteristic of high reactive infants, occurred in about 20% of Caucasian 4-month-olds. This category of infant was rare among the Chinese infants (Kagan et al., 1994). Kagan, Kearsley, and Zelazo (1978) studied ChineseAmerican and Caucasian infants living in contiguous Boston neighborhoods who were either attending the same daycare center or being reared only at home. The Chinese-American infants, whether attending the center or reared only at home, showed behavioral profiles that differed from the profiles displayed by the Caucasian infants. The Chinese-American infants smiled, laughed, and vocalized less often; as toddlers, stayed closer to their mothers in unfamiliar rooms with children they did not know; and, in addition, displayed remarkably stable resting heart rates. Geneticists have discovered that the proportion of humans possessing the long allele in the promoter region of the gene for the serotonin transporter is high among Africans, moderately high among Caucasians, and lowest among East Asians who are most likely to inherit the short allele (Chiao & Blizinsky,
2010; Li et al., 2008; Spielman et al., 2007). Possession of the short allele is accompanied by a lower concentration of the serotonin transporter and, as a result, serotonin remains in the synapses for a slightly longer time. Most neurobiologists believe that the prolonged presence of serotonin leads eventually to lower chronic levels of serotonin activity due to a gradual reduction in the number of serotonin receptors and/or an inhibitory feedback loop from the serotonin neurons to the raphe nucleus, which is the source of brain serotonin (Chiao & Blizinsky, 2010; Gelernter, Kranzler, & Cubells, 1997). Either or both mechanisms would lead to chronically lower levels of brain serotonin. Because serotonin contributes to behavioral signs of pleasure, such as smiling and laughing, the greater prevalence of the short allele among East Asians might explain why Chinese infants from Beijing and ChineseAmerican infants from Boston smiled and laughed less frequently than Caucasian infants (Kagan, 2010).
Three perspectives on contexts The evidence supports three positions regarding the generality of a concept based on one source of information gathered in one setting on one occasion. The most popular position assumes that the participants possess the presumed property even if they do not display it in all relevant contexts. This view is reasonable for sensory capacities and representations stored in long-term memory, although there are exceptions. A less frequent perspective assumes that a property ascribed to an agent possesses special features when expressed that it does not have when not observed. Most 4-year-olds point correctly at the cow when they are shown pictures of a cow, cup, and car and are asked to point to the animal, implying that the children have some representation of the semantic concept animal. But that knowledge lacks many of the significant features of the concept animal understood by adults. The least popular solution urges psychologists to combine a description of an agent’s properties with the features of the observational setting, the source of evidence, and the characteristics of the participants. This solution is essential when the concepts refer to emotions, values, personality traits, and cognitive processes because of the serious disagreements over the intrinsic features of these constructs. Put plainly, each class of context is associated with a set of probabilities describing the likelihood of particular outcomes. Change the context and those probabilities change. The abstract concept of altruism is an example. The probability that an adult will help a stranger who appears to be blind, based on direct observations, was high in Rochester, NY, but low in Chattanooga, TN. However, residents of Chattanooga were more likely than those in Rochester to aid a stranger who appeared to be injured (Levine, 2003). The suggestion that psychologists replace the individual or one of the individual’s properties as the primary element in theory with the individual in a context awards equal power to genes and brains, on the one hand, and to culture, historical era, social class, and the local setting, on the other—a position argued persuasively by Mischel (2004) and Nisbett (2003),
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along with others. The injunction inscribed on the Oracle at Delphi, ‘‘Know thyself,’’ should be reworded to read, ‘‘Know thyself in each context.’’ Psychologists and psychiatrists are fond of writing sentences such as ‘‘Individuals with the short allele of the serotonin transporter are vulnerable to depression if they have experienced past stressors’’ when this relation was found with one sample using one source of evidence. I suggest that psychologists should more often write sentences such as ‘‘Women with a European pedigree possessing the short allele of the serotonin transporter who live in a large city far from their family, and grew up as a later born child in an economically disadvantaged family are at risk for a depression based on information gathered in an interview that asked about current moods and memories of early and recent stressors.’’ I make this suggestion because of evidence implying that if the above sentence referred to middle-class Japanese men with the short allele who said they had harshly socializing fathers, then the presumed risk for depression would not be valid (Wagatsuma, 1977).
Maturation The third assumption I had not awarded sufficient significance as a young investigator is the influence of brain maturation on the patterns of behaviors observed over the first dozen years. The second half of the 1st year, for example, is marked by a large number of anatomical changes in prefrontal cortex and hippocampus (Chrousos & Gold, 1992; Huttenlocher, 1990; Mrzljak, Uylinges, van Eden, & Judas, 1990). It cannot be a coincidence that these structural changes occur at the same time that developmental psychologists observe a significant improvement in working memory (Fox, Kagan, & Weiskopf, 1979; Reznick, Morrow, Goldman, & Snyder, 2004). The biological changes permit infants older than 7 or 8 months to hold representations of recent experience in an active state for a longer time and to retrieve representations of events that occurred minutes or days earlier (Kagan & Herschkowitz, 2005). There is a U-shaped function between age and duration of looking at a variety of visual stimuli across the 4- to 12-month interval in many different samples of infants (Kagan, 1971; Kagan et al., 1978). Duration of looking is high from 4 to 6 months, low at 7 to 8 months, and increases after 8 months to the end of the 1st year. Courage, Reynolds, and Richards (2006) replicated this function with eight different categories of visual stimuli, and Hsu (2010) reported the same U-shaped function for the retrieval of an operant response following varied delays after the original conditioning experience. This robust developmental function helps explain why crying in response to a stranger and to temporary separation from the primary caretaker usually emerges after 7 to 8 months in most infants (Kagan, 1971). One implication is that the theoretical meaning of looking time in infants younger than 7 months may differ from its meaning in infants older than 8 months. A majority of the investigators studying the cognitive competences of infants rely only on changes in looking time and many
fail to acknowledge how this important transition in the middle of the 1st year affects this measure (Kagan, 2008). The child’s 2nd year provides an equally persuasive example of the influence of maturational changes on psychological functioning. This 12-month interval is marked by the appearance of at least four new competences that either are absent or are fragile during the 1st year. These include meaningful speech, the capacity to infer select cognitive and feeling states in others, representations of actions adults prohibit and an initial understanding of the concept of right and wrong, and, finally, the first signs of a conscious awareness of self’s feelings and intentions. The close correspondence in the time of emergence of these functions, typically between 14 and 20 months, suggests that they share a universal set of changes in brain that are necessary but probably not sufficient for their actualization (Kagan, 1981). The most important anatomical change is an elongation of the spines on the neurons of layer 3 that connect the right and left hemispheres. This growth should be accompanied by more efficient communication between the two hemispheres via the corpus callosum (Mrzljak et al., 1990). Hence, when a 2-yearold sees a cup, the acquired perceptual schemata for cups, represented primarily in the right hemisphere, will be rapidly integrated with the semantic representation for cup in the left and motivate the child to say ‘‘cup.’’ The enhanced hemisphere connectivity could also explain why 2-year-olds infer select emotional states in others. The visceral schemata that represent past feelings, stored primarily but not exclusively in the right hemisphere, will be rapidly integrated with semantic representations of the state of another represented in the left hemisphere (Sato & Aoki, 2006). The new ability to infer the mind of another helps explain why an initial understanding of right and wrong, as well as the semantic concepts good and bad, emerge in the 2nd year. When an examiner models three coherent actions with toys and then says to the child, ‘‘It’s your turn to play,’’ many 2-year-olds, but very few 1-year-olds, cry because they infer that the adult wishes them to imitate the prior actions and they are aware of their inability to do so. Their distress implies that they inferred that a failure to perform might provoke adult disapproval. This inference requires a comprehension of the meaning of ought and the consequences of improper actions. A group of my students studied children from 12 to 24 months of age, who were growing up in Cambridge, one of the Fiji islands, or in California as recent Vietnamese immigrants. They discovered that the peak distress to an adult who had modeled three actions occurred when the children were between 18 to 24 months old (Kagan, 1981). The appearance of an early form of self-awareness is implied by the observation that 18- to 24-month-olds begin to direct adults to behave in particular ways, lower their head as if ashamed when they cannot perform a task, and describe what they are doing as they are doing it (Kagan, 1981). The coordination of visceral schemata for the child’s feeling tone, represented primarily in the orbitofrontal prefrontal cortex of the right hemisphere, with the semantic categories representing
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the self’s properties, represented primarily in the left, could contribute to what psychologists call consciousness. One obvious implication of this maturational transition is that we should expect different predictive relations between the characteristics children display before their 1st birthday compared with the competences and traits present at 2 years of age and most later outcomes. The evidence supports that expectation (Kagan, 1971; Kagan & Moss, 1962). These transitions in psychological functioning can be likened to the changes in mode of travel during a journey. One drives to the airport, flies to Athens, and sails to Heraklion.
preconceptions. When Freeman Dyson was a young physicist, he showed some mathematical calculations to Enrico Fermi that he believed explained Fermi’s empirical observations on the scatter of mesons. When Fermi asked how many open parameters Dyson had used, the younger man confessed that his equations had four open parameters. Fermi’s reply captures my sentiments regarding the ambiguous nature of many psychological constructs: ‘‘Johnny von Neumann used to say that with four parameters I could make an elephant and with five I can make him wiggle his trunk.’’ Editor’s Note
Summary In this article, I urge psychologists to give more serious attention to patterns of measurements; to be sensitive to the influence of the features of the measurement context and the gender, ethnicity, and cultural background of the participants; and, for those studying children, to be aware of the child’s developmental stage. The corpus of data gathered during the study of day care by Kearsley, Zelazo, and myself, mentioned earlier, illustrates the usefulness of these three recommendations. We studied 116 children belonging to one of two ethnic groups (ChineseAmerican or European-American) who were attending a daycare center we administered or who were reared only at home. The daycare and home-reared groups were matched on ethnicity, gender, and class, and the children were administered a number of different procedures on each of eight evaluations conducted from 3.5 to 29 months of age. The specific procedure and its setting had the largest effect on the behaviors we coded. The frequencies of motor activity, avoidance, smiling, vocalizing, crying, and duration of attention were profoundly dependent on the task and the context. Maturation had the second most significant effect. The frequencies of the above behaviors displayed before 8 months were very different from those displayed after 8 months. Ethnicity accounted for the third largest amount of variance. The Chinese-American infants, whether in the day care or home groups, smiled and vocalized less often, were more avoidant, and had more stable heart rates at every age. Finally, patterns that combined smiling, vocalizing, avoidance of novelty, and heart rate variability best distinguished the Chinese-American children from the European-Americans. To our surprise, the differences between the daycare and homereared children were minimal. Too many contemporary psychological concepts are contextually naked. Constructs such as fear or stress do not specify the agent (mouse, monkey, or human), the source of the fear or stress (body restraint, separation from the mother, or sexual abuse), or the evidence on which the attribution of fear or stress is based (body immobility, distress vocalizations, potentiated startle, or a verbal report on a questionnaire). This indifference to specifying a context for all theoretical ideas makes concepts like fear or stress open terms, analogous to the open parameters in the equations of physicists and economists who insert any value that fits their
This article is the first in the ‘‘Three Things’’ series—occasional pieces written by distinguished faculty members at or near retirement. These articles provide the opportunity to write about three things they have learned in their careers that they want to share with the rest of us.
Declaration of Conflicting Interests The author declared that he had no conflicts of interest with respect to his authorship or the publication of this article.
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Mrzljak, L., Uylings, H.B., van Eden, C.G., & Judas, M. (1990). Neuronal development in human prefrontal cortex in prenatal and postnatal stages. Progress in Brain Research, 85, 185–222. Nisbett, R.E. (2003). The geography of thought. New York: Free Press. Patten, S.B. (2010). Correspondence. Psychological Medicine, 40, 1757–1758. Raczka, K.A., Gartmann, N., Mechias, M.L., Reif, A., Buchel, C., Deckert, J., & Kalisch, R. (in press). A neuropeptide S receptor variant associated with over-interpretation of fear reactions. Molecular Psychiatry. Reznick, J.S., Morrow, J.D., Goldman, B.D., & Snyder, J. (2004). The onset of working memory in infants. Infancy, 6, 145–154. Riggio, H.R., & Riggio, R.E. (2002). Emotional expressiveness, extraversion, and neuroticism: A meta-analysis. Journal of Nonverbal Behavior, 26, 1321–1348. Sato, W. & Aoki, S. (2006). Right hemispheric dominance in processing of unconscious negative emotion. Brain and Cognition, 62, 261–266. Schiff, M., Duyme, M., Dumaret, A., Stewart, J., Tomkiewicz, S., & Feingold, J. (1978). Intellectual status of working-class children adopted early into upper-middle class families. Science, 200, 1503–1504. Schreier, S.S., Heinrichs, N., Alden, L., Rapee, R.M., Hofmann, S.G., Chen, J., et al. (2010). Social anxiety and social norms in individualistic and collectivistic countries. Depression and Anxiety, 27, 1128–1134. Schwartz, C.E., Kunwar, S., Greeve, D.N., Moran, L.R., Viner, J.C., Covino, J.M., et al. (2010). Structural differences in adult orbital and ventromedial prefrontal cortex predicted by infant temperament at four months of age. Archives of General Psychiatry, 67, 1–7. Simm, R.W., & Nath, L.E. (2004). Gender and emotion. American Journal of Sociology, 109, 1137–1176. Spielman, R.S., Bastone, L.A., Burdick, J.T., Morley, M., Ewens, W.J., & Cheung, V.G. (2007). Common genetic variants accounts for differences in gene expression among ethnic groups. Nature Genetics, 39, 226–231. Striano, T., & Bushnell, E.W. (2005). Haptic perception of material properties by 3-month-old infants. Infant Behavior and Development, 28, 266–289. Vervaecke, H., De Vries, H., & Van Elsacker, L. (1999). An experimental evaluation of the consistency of competitive ability and agnostic dominance in different social contexts in captive bonobos. Behavior Genetics, 136, 423–442. Wagatsuma, H. (1977). Some aspects of the contemporary Japanese family. Daedalus, 106, 181–210. Westman, J., Hasselstrom, J., Johannson, S.E., & Sundquist, J. (2003). The influence of place of birth and socio-economic factors on attempted suicide in a defined population of 4.5 million people. Archives of General Psychiatry, 60, 409–414. Woodward, S.A., Lenzenweger, M.F., Kagan, J., Snidman, N., & Arcus, D. (2000). Taxonic structure of infant reactivity: Evidence from a taxometric perspective. Psychological Science, 11, 296–301.
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Three Lessons Learned Jerome Kagan Department of Psychology, Harvard University, Cambridge, MA
Abstract In this article, I describe varied observations from the past 60 years that motivated three significant changes in the assumptions I held as a young psychologist interested in the development of children. Aspects of these early assumptions penetrate a great deal of current research. The new beliefs are (a) a greater willingness to base concepts on patterns of measurements rather than single independent or dependent variables, (b) learning to include the physical features of the observational setting, including the procedure that generated the evidence, as well as the participants’ gender, social class, and cultural background, as part of the concept, and (c) remaining aware of the possibility that the relations among continuous variables can change as a function of brain maturation during the early stages of childhood. Keywords child development, scientific methodology
Close to 60 years of reflection on experimental observations in laboratories and naturalistic observations in homes, schools, playgrounds, and backyards have forced me to revise a number of assumptions I held on that warm day in 1954 when I received my Ph.D. This article describes three significant changes in my earlier beliefs about the development of cognitive competences, morality, and the balance between experience and biology in creating psychological variation among children. The new beliefs had their origins in collaborative research with many students and colleagues and, fortunately, find support in the empirical work of others. One belief calls for basing a larger number of constructs on patterns of causal conditions and outcomes rather than on the relation between one incentive and one dependent variable. A second belief is that the setting of the observation, as well as the gender, social class, and cultural background of the participants, often limit the generality of an inferred construct. The third new belief recognizes that the relations among measurements are often a function of the child’s maturational stage, especially during the opening years of development. The editor requested that the arguments in this article be based primarily on work from my laboratory. Hence, the frequent references to the research of my students and colleagues should not be interpreted as a narcissistic indifference to the significant efforts of many psychologists who have made the same claims, often with better evidence and more coherent prose.
Look For Patterns Most—I am tempted to say all—of the phenomena psychologists study can result from more than one set of conditions, whether the observations refer to motor behaviors, verbal reports, or biological processes. This implies that the probability of discovering robust relations between a class of incentive and a category of outcome will be enhanced by looking for patterns of measures, rather than focusing on single, usually continuous, variables.
Infant temperaments Persuasive support for the significance of patterns is found in research on high and low reactive infant temperaments. Initially, my students and I had affirmed the variation in the frequency of avoidant reactions to unfamiliar situations or people among 2-year-old children. We called the consistently shy, avoidant 2-year olds inhibited to the unfamiliar and the sociable, bold children uninhibited. It seemed useful to search for the infant behaviors that might predict these two behavioral categories in older children (Kagan, 1994). We filmed the behaviors of more than 450 4-month-old, middle-class, Caucasian infants to nonthreatening, but unfamiliar, visual, auditory, and olfactory events. About 20% of the Corresponding Author: Jerome Kagan, Department of Psychology, Harvard University, 33 Kirkland St., Cambridge, MA 02138 E-mail: [email protected]
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infants combined vigorous limb activity, arching of the back, and frequent crying to these incentives, and we labeled these infants high reactive. In addition, 40% showed the complementary pattern of minimal motor activity, few arches of the back, and little crying, but occasional smiling and babbling, and we labeled these infants low reactive. Two other groups were characterized either by vigorous motor activity with little crying or minimal motor activity with frequent crying. We could have created a continuous variable of arousal to novelty and given each infant a score based on the average of the standardized values for motor activity, arching, crying, smiling, and vocalizing. However, we created high and low reactive categories based only on combinations of motor activity and crying because we believed that these two types of infants varied in the excitability of the amygdala. The work of neurobiologists indicated that an activated amygdala could mediate limb activity, arching of the back, and crying, but it was less obvious that an excitable amygdala mediated the more pleasant affect states reflected in babbling and smiling (Adamec, 1991). That decision turned out to be fruitful. Longitudinal observations of these infants revealed that the behavioral and biological features of the high and low reactives remained different from age 1 to 18 (Kagan, 1994; Kagan & Snidman, 2004; Kagan, Snidman, Kahn, & Towsley, 2007). One of five high reactives (20%), but not one low reactive, combined high levels of avoidance to unfamiliar events in the 2nd year with minimal talking with an examiner, a large brain stem evoked potential from the inferior colliculus to click sounds, and a large event related waveform in frontal sites to discrepant visual scenes at 11 years of age. By contrast, one of four low reactives (25%), but not one high reactive, at age 11 combined high vagal tone in the cardiovascular system, low systolic blood pressure, greater EEG activation in the left rather than right frontal lobe, a small brain stem evoked potential to the click sounds, and a small event related waveform to the discrepant scenes (Kagan & Snidman, 2004). Carl Schwartz assessed 135 of these youths at age 18 using MRI technology. The high reactives had significantly thicker values in a small area in the right ventromedial cortex. This area projects to the amygdala and the central gray. The latter site mediates arching of the back, which was so frequent among high reactive infants at 4 months of age (Schwartz et al., 2010). High reactive adolescents are at a higher risk for developing social phobia than low reactives, but not all social phobics were high reactive infants. Therefore, clinicians and investigators would profit from trying to determine which patients with social phobia began life with a temperamental bias and which developed their symptoms as a sole result of experience. Had we given each infant a score on a continuous index of arousal, none of these predictive relations would have emerged. A taxonic analysis of the infant data by Woodward, Lenzenweger, Kagan, Snidman, and Arcus (2000) and Loken’s (2001) latent class analysis of the more extensive evidence gathered from 4 months to 7 years of age affirmed the wisdom of our decision to create categories of infants based on patterns of behaviors. In
addition, Fox, Henderson, Rubin, Calkins, and Schmidt (2001) have replicated some of these results and confirmed the utility of basing the classification of these two infant temperamental biases on patterns of motor activity and crying. Hinde (1998) provided a persuasive example of the utility of searching for patterns when there are nonlinear relations among measures. A group of 4-year-olds were observed in a preschool setting and also with their mothers at home. Mothers who combined moderate levels of warmth and control, rather than low or high levels, had children who displayed very low levels of aggression. This relation would not have emerged if Hinde had treated the three critical variables as continua and computed correlations among them.
Newborn responsiveness to sounds Almost 40 years ago, a graduate student in Harvard wanted to discover which features of sound would alert newborn infants. He recorded the behaviors of 2-day-old infants to 27 sounds, each sound composed of one of three frequencies, one of three loudness levels, and one of three rise times. After spending several years gathering and analyzing the data with an analysis of variance, he discovered that no particular pitch, loudness, or rise time had a special influence on the infants’ behavior. Frustrated, and in need of advice, I suggested that he look for the one or two stimuli that produced the most obvious signs of alerting in a majority of newborns. After implementing this analysis, he discovered one pattern that fit this criterion. This stimulus, which combined one particular pitch, loudness, and rise time, bore the closest resemblance to the human voice (Kearsley, 1973).
Patterns of verbal reports and behavior The suggestion to base more concepts on patterns of evidence implies that sole reliance on verbal reports, whether from informants or those familiar with them, should be supplemented with behavioral and/or biological measurements, because the same verbal description of a psychological state can originate in different life histories and be accompanied by different brain and psychological states. There are many reasons for this claim. First, individuals vary in their networks of representations of past feelings and images that are linked to the words. No person has conscious access to these implicit knowledge networks or their brain states, each of which can affect their verbal replies. Second, most children and adults are reluctant to admit to actions, traits, or feelings that might be embarrassing or provoke a critical appraisal from the examiner. A shy, avoidant personality is more acceptable in Japan than in the Netherlands. Thus, it is not surprising that Japanese college students reported much higher levels of social anxiety than Dutch students (Schreier et al., 2010). Most important, the correlations between what people say about themselves, or what others say, and their actual traits or actions are usually small (Di Bartolo & Grills, 2006; Riggio
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& Riggio, 2002). The mothers’ descriptions of shyness and timidity in the 11-year-old high and low reactives were not significantly correlated with the child’s past or present behavior. However, when we combined these descriptions with the child’s behavior in the laboratory, we were able to differentiate the high and low reactives (Kagan & Snidman, 2004). Filmed interviews of these youths when they were 15 years old provide a clear example of the mismatch between what people say and their actual behavior. A number of high reactive adolescents told the interviewer that they were neither shy nor anxious with strangers. But these adolescents frequently looked away from the interviewer, and a few never looked directly at her during the 3-hr interview in their homes. By contrast, not one low reactive adolescent who denied being shy shifted their gaze from the interviewer’s face (Kagan, Snidman, Kahn, & Towsley, 2007). Thus, the addition of behavioral observations to the verbal reports permitted us to distinguish between two groups of adolescents who gave exactly the same verbal description of this personality trait. The potential mismatch between what adults say about their past and what objective observations would reveal has special relevance for investigators who attribute current psychological problems to the occurrence of past stressors, when the evidence for the latter comes only from the adults’ fallible recall of their childhoods. Some individuals possess a brain chemistry that leads them to exaggerate the distress accompanying rejection, abuse, or bullying in the past; others have a chemistry that leads them to minimize the level of distress experienced to the same stressor (Patten, 2010; Raczka et al., in press). Thus, variation in verbal descriptions of past stressful experiences becomes a phenomenon to understand rather than the obvious cause of contemporary problems. I suspect that psychologists know that political candidates, seducers, and salespersons say things they do not believe. It is difficult, therefore, to understand why many investigators who rely only on verbal reports assume that a stranger’s answers to their questions are by and large truthful and accurate.
Statistics and patterns The decision to base concepts either on continuous measurements of one variable or on patterns of measures should be determined by a priori, theoretical hunches. A majority of psychologists prefer concepts based on quantitative differences in single continuous measurements because of the statistical techniques they were taught and the demands of reviewers, rather than theory. The problem is that correlations and analyses of variance or covariance were not designed to be especially sensitive detectors of patterns that involve nonlinear relations among the measures—recall Kearsley’s work with newborns and Hinde’s study of children. Until statisticians invent better methods to detect patterns, psychologists will rely on regression and covariance to control for conditions they want to believe are not a necessary element in a causal cascade in which one particular condition of interest leads to some outcome.
For example, psychologists typically rely on covariance techniques to prove that one condition, say abuse, daycare, or bullying during childhood, makes a significant contribution to an outcome that is correlated with the participants’ social class by statistically controlling for the effects of social class. However, this strategy can sometimes lead to the misleading conclusion that the single condition had a causal influence that did not require it being part of a larger pattern that included the social class of the participants. Imagine a scientist who was convinced that a cold temperature made a significant, independent contribution to yearly snowfall levels. This investigator used covariance to control for the influence of relative humidity and would probably find that cold temperatures did account for a small but significant amount of the variation in snowfall. But that conclusion is flawed because snow only falls when both conditions are present. Magnusson and Torestad (1993) appreciate the importance of patterns: ‘‘Pattern description is the first step to an understanding and explanation of the lawfulness of individual functioning. Its main merit ... is that it considers the holistic character of the function of subsystems’’ (p. 445).
The Context and Generality All scientists hope that the concept they invented to explain a new phenomenon is not restricted to the context in which the observations were gathered. Although physicists have been successful at imagining concepts that apply across an extraordinary range of situations, psychologists have found it more difficult to infer concepts that apply to settings very different from the ones that gave rise to the evidence. One reason for this frustration is an inadequate understanding of the fundamental mechanisms mediating the phenomenon. Although biologists agree that DNA strings are the foundations of the protein content of all cells, psychologists are not yet close to an accord on the basic elements or processes that underlie actions, beliefs, or emotions. Hence, they disagree on the defining properties of many popular concepts, including memory, emotion, regulation, morality, stress, and reward. For that reason, the generality of a concept is often restricted to a particular class of context. The term context has both a narrow and a broad definition. The former refers to the physical and social features of the setting, especially its familiarity, the presence of others, and the procedure that produced a specific class of evidence. Variation in these features often affects the outcome. For example, 3-month-old infants display behaviors indicating that they are able to discriminate between a heavy and a light object, as they will hold the lighter object for a longer time. However, this ability is only observed when the infants are tested in a dark room and does not occur when the room is fully illuminated (Striano & Bushnell, 2005). The probability that one bonobo chimpanzee will dominate another depends on whether only two chimps are interacting or a third animal is present (Vervaecke, De Vries, & Van Elsacker, 1999).
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A broad definition of context, which applies primarily but not exclusively to humans who interpret the symbolic meaning of a setting, include the participant’s gender, ethnicity, developmental stage, social class, and cultural background. Because the subjective construal of a measurement context varies with these symbolic categories, psychologists should be concerned by the fact that most of the world’s research on humans is conducted in English by Americans on Americans, often college students with a European pedigree (Arnett, 2008; see Henrich, Heine, & Norenzayan, 2010, for a similar argument).
Ethnicity and class A person’s social class exerts a significant influence on a host of behaviors because class of rearing is associated with distinctive experiences in home and school, an identification with a privileged or less privileged group, an awareness of the differences in potency between self and others, and the biological response to particular challenges (Lahti et al., 2006; Manuck, Flory, Ferrell, & Muldoon, 2004). The robust correlations among adults in developed nations between social class and IQ scores, academic grades, vocation, anxiety and depressive disorders, health, divorce, and antisocial behavior cannot be attributed only to genes (Adler et al., 1994; Schiff et al., 1978; Simm & Nath, 2004). The combined influence of class and ethnicity was apparent in a study of the likelihood of a suicide attempt by residents of Sweden. To predict this rare action, the investigators had to examine both the person’s national origin and social class. Lower class women who had been born in Finland and upper-middle-class women born in East Asia had the highest suicide risk (Westman, Hasselstrom, Johannson, & Sundquist, 2003). The influence of ethnicity was revealed in the different reactions 4-month-old Caucasian infants from Boston or Dublin and Chinese infants from Beijing displayed to the episodes used to categorize infants as high or low reactive. Recall that a combination of high motor activity and crying, characteristic of high reactive infants, occurred in about 20% of Caucasian 4-month-olds. This category of infant was rare among the Chinese infants (Kagan et al., 1994). Kagan, Kearsley, and Zelazo (1978) studied ChineseAmerican and Caucasian infants living in contiguous Boston neighborhoods who were either attending the same daycare center or being reared only at home. The Chinese-American infants, whether attending the center or reared only at home, showed behavioral profiles that differed from the profiles displayed by the Caucasian infants. The Chinese-American infants smiled, laughed, and vocalized less often; as toddlers, stayed closer to their mothers in unfamiliar rooms with children they did not know; and, in addition, displayed remarkably stable resting heart rates. Geneticists have discovered that the proportion of humans possessing the long allele in the promoter region of the gene for the serotonin transporter is high among Africans, moderately high among Caucasians, and lowest among East Asians who are most likely to inherit the short allele (Chiao & Blizinsky,
2010; Li et al., 2008; Spielman et al., 2007). Possession of the short allele is accompanied by a lower concentration of the serotonin transporter and, as a result, serotonin remains in the synapses for a slightly longer time. Most neurobiologists believe that the prolonged presence of serotonin leads eventually to lower chronic levels of serotonin activity due to a gradual reduction in the number of serotonin receptors and/or an inhibitory feedback loop from the serotonin neurons to the raphe nucleus, which is the source of brain serotonin (Chiao & Blizinsky, 2010; Gelernter, Kranzler, & Cubells, 1997). Either or both mechanisms would lead to chronically lower levels of brain serotonin. Because serotonin contributes to behavioral signs of pleasure, such as smiling and laughing, the greater prevalence of the short allele among East Asians might explain why Chinese infants from Beijing and ChineseAmerican infants from Boston smiled and laughed less frequently than Caucasian infants (Kagan, 2010).
Three perspectives on contexts The evidence supports three positions regarding the generality of a concept based on one source of information gathered in one setting on one occasion. The most popular position assumes that the participants possess the presumed property even if they do not display it in all relevant contexts. This view is reasonable for sensory capacities and representations stored in long-term memory, although there are exceptions. A less frequent perspective assumes that a property ascribed to an agent possesses special features when expressed that it does not have when not observed. Most 4-year-olds point correctly at the cow when they are shown pictures of a cow, cup, and car and are asked to point to the animal, implying that the children have some representation of the semantic concept animal. But that knowledge lacks many of the significant features of the concept animal understood by adults. The least popular solution urges psychologists to combine a description of an agent’s properties with the features of the observational setting, the source of evidence, and the characteristics of the participants. This solution is essential when the concepts refer to emotions, values, personality traits, and cognitive processes because of the serious disagreements over the intrinsic features of these constructs. Put plainly, each class of context is associated with a set of probabilities describing the likelihood of particular outcomes. Change the context and those probabilities change. The abstract concept of altruism is an example. The probability that an adult will help a stranger who appears to be blind, based on direct observations, was high in Rochester, NY, but low in Chattanooga, TN. However, residents of Chattanooga were more likely than those in Rochester to aid a stranger who appeared to be injured (Levine, 2003). The suggestion that psychologists replace the individual or one of the individual’s properties as the primary element in theory with the individual in a context awards equal power to genes and brains, on the one hand, and to culture, historical era, social class, and the local setting, on the other—a position argued persuasively by Mischel (2004) and Nisbett (2003),
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along with others. The injunction inscribed on the Oracle at Delphi, ‘‘Know thyself,’’ should be reworded to read, ‘‘Know thyself in each context.’’ Psychologists and psychiatrists are fond of writing sentences such as ‘‘Individuals with the short allele of the serotonin transporter are vulnerable to depression if they have experienced past stressors’’ when this relation was found with one sample using one source of evidence. I suggest that psychologists should more often write sentences such as ‘‘Women with a European pedigree possessing the short allele of the serotonin transporter who live in a large city far from their family, and grew up as a later born child in an economically disadvantaged family are at risk for a depression based on information gathered in an interview that asked about current moods and memories of early and recent stressors.’’ I make this suggestion because of evidence implying that if the above sentence referred to middle-class Japanese men with the short allele who said they had harshly socializing fathers, then the presumed risk for depression would not be valid (Wagatsuma, 1977).
Maturation The third assumption I had not awarded sufficient significance as a young investigator is the influence of brain maturation on the patterns of behaviors observed over the first dozen years. The second half of the 1st year, for example, is marked by a large number of anatomical changes in prefrontal cortex and hippocampus (Chrousos & Gold, 1992; Huttenlocher, 1990; Mrzljak, Uylinges, van Eden, & Judas, 1990). It cannot be a coincidence that these structural changes occur at the same time that developmental psychologists observe a significant improvement in working memory (Fox, Kagan, & Weiskopf, 1979; Reznick, Morrow, Goldman, & Snyder, 2004). The biological changes permit infants older than 7 or 8 months to hold representations of recent experience in an active state for a longer time and to retrieve representations of events that occurred minutes or days earlier (Kagan & Herschkowitz, 2005). There is a U-shaped function between age and duration of looking at a variety of visual stimuli across the 4- to 12-month interval in many different samples of infants (Kagan, 1971; Kagan et al., 1978). Duration of looking is high from 4 to 6 months, low at 7 to 8 months, and increases after 8 months to the end of the 1st year. Courage, Reynolds, and Richards (2006) replicated this function with eight different categories of visual stimuli, and Hsu (2010) reported the same U-shaped function for the retrieval of an operant response following varied delays after the original conditioning experience. This robust developmental function helps explain why crying in response to a stranger and to temporary separation from the primary caretaker usually emerges after 7 to 8 months in most infants (Kagan, 1971). One implication is that the theoretical meaning of looking time in infants younger than 7 months may differ from its meaning in infants older than 8 months. A majority of the investigators studying the cognitive competences of infants rely only on changes in looking time and many
fail to acknowledge how this important transition in the middle of the 1st year affects this measure (Kagan, 2008). The child’s 2nd year provides an equally persuasive example of the influence of maturational changes on psychological functioning. This 12-month interval is marked by the appearance of at least four new competences that either are absent or are fragile during the 1st year. These include meaningful speech, the capacity to infer select cognitive and feeling states in others, representations of actions adults prohibit and an initial understanding of the concept of right and wrong, and, finally, the first signs of a conscious awareness of self’s feelings and intentions. The close correspondence in the time of emergence of these functions, typically between 14 and 20 months, suggests that they share a universal set of changes in brain that are necessary but probably not sufficient for their actualization (Kagan, 1981). The most important anatomical change is an elongation of the spines on the neurons of layer 3 that connect the right and left hemispheres. This growth should be accompanied by more efficient communication between the two hemispheres via the corpus callosum (Mrzljak et al., 1990). Hence, when a 2-yearold sees a cup, the acquired perceptual schemata for cups, represented primarily in the right hemisphere, will be rapidly integrated with the semantic representation for cup in the left and motivate the child to say ‘‘cup.’’ The enhanced hemisphere connectivity could also explain why 2-year-olds infer select emotional states in others. The visceral schemata that represent past feelings, stored primarily but not exclusively in the right hemisphere, will be rapidly integrated with semantic representations of the state of another represented in the left hemisphere (Sato & Aoki, 2006). The new ability to infer the mind of another helps explain why an initial understanding of right and wrong, as well as the semantic concepts good and bad, emerge in the 2nd year. When an examiner models three coherent actions with toys and then says to the child, ‘‘It’s your turn to play,’’ many 2-year-olds, but very few 1-year-olds, cry because they infer that the adult wishes them to imitate the prior actions and they are aware of their inability to do so. Their distress implies that they inferred that a failure to perform might provoke adult disapproval. This inference requires a comprehension of the meaning of ought and the consequences of improper actions. A group of my students studied children from 12 to 24 months of age, who were growing up in Cambridge, one of the Fiji islands, or in California as recent Vietnamese immigrants. They discovered that the peak distress to an adult who had modeled three actions occurred when the children were between 18 to 24 months old (Kagan, 1981). The appearance of an early form of self-awareness is implied by the observation that 18- to 24-month-olds begin to direct adults to behave in particular ways, lower their head as if ashamed when they cannot perform a task, and describe what they are doing as they are doing it (Kagan, 1981). The coordination of visceral schemata for the child’s feeling tone, represented primarily in the orbitofrontal prefrontal cortex of the right hemisphere, with the semantic categories representing
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the self’s properties, represented primarily in the left, could contribute to what psychologists call consciousness. One obvious implication of this maturational transition is that we should expect different predictive relations between the characteristics children display before their 1st birthday compared with the competences and traits present at 2 years of age and most later outcomes. The evidence supports that expectation (Kagan, 1971; Kagan & Moss, 1962). These transitions in psychological functioning can be likened to the changes in mode of travel during a journey. One drives to the airport, flies to Athens, and sails to Heraklion.
preconceptions. When Freeman Dyson was a young physicist, he showed some mathematical calculations to Enrico Fermi that he believed explained Fermi’s empirical observations on the scatter of mesons. When Fermi asked how many open parameters Dyson had used, the younger man confessed that his equations had four open parameters. Fermi’s reply captures my sentiments regarding the ambiguous nature of many psychological constructs: ‘‘Johnny von Neumann used to say that with four parameters I could make an elephant and with five I can make him wiggle his trunk.’’ Editor’s Note
Summary In this article, I urge psychologists to give more serious attention to patterns of measurements; to be sensitive to the influence of the features of the measurement context and the gender, ethnicity, and cultural background of the participants; and, for those studying children, to be aware of the child’s developmental stage. The corpus of data gathered during the study of day care by Kearsley, Zelazo, and myself, mentioned earlier, illustrates the usefulness of these three recommendations. We studied 116 children belonging to one of two ethnic groups (ChineseAmerican or European-American) who were attending a daycare center we administered or who were reared only at home. The daycare and home-reared groups were matched on ethnicity, gender, and class, and the children were administered a number of different procedures on each of eight evaluations conducted from 3.5 to 29 months of age. The specific procedure and its setting had the largest effect on the behaviors we coded. The frequencies of motor activity, avoidance, smiling, vocalizing, crying, and duration of attention were profoundly dependent on the task and the context. Maturation had the second most significant effect. The frequencies of the above behaviors displayed before 8 months were very different from those displayed after 8 months. Ethnicity accounted for the third largest amount of variance. The Chinese-American infants, whether in the day care or home groups, smiled and vocalized less often, were more avoidant, and had more stable heart rates at every age. Finally, patterns that combined smiling, vocalizing, avoidance of novelty, and heart rate variability best distinguished the Chinese-American children from the European-Americans. To our surprise, the differences between the daycare and homereared children were minimal. Too many contemporary psychological concepts are contextually naked. Constructs such as fear or stress do not specify the agent (mouse, monkey, or human), the source of the fear or stress (body restraint, separation from the mother, or sexual abuse), or the evidence on which the attribution of fear or stress is based (body immobility, distress vocalizations, potentiated startle, or a verbal report on a questionnaire). This indifference to specifying a context for all theoretical ideas makes concepts like fear or stress open terms, analogous to the open parameters in the equations of physicists and economists who insert any value that fits their
This article is the first in the ‘‘Three Things’’ series—occasional pieces written by distinguished faculty members at or near retirement. These articles provide the opportunity to write about three things they have learned in their careers that they want to share with the rest of us.
Declaration of Conflicting Interests The author declared that he had no conflicts of interest with respect to his authorship or the publication of this article.
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