The developmental approach toward mental retardation historically has examined whether retarded individuals behave as do nonretarded individuals. An alternative approach involves using data from handicapped populations as “experiments of nature” to provide information about typical developmental processes. Three examples of this use of mental retardation findings include examinations of sequences, rates, and cross-domain relations. Certain instances of universal sequences appear to have been replicated by findings from children with mental retardation, but in other cases mentally retarded children help illustrate the extremes to which certain individual styles of development can be taken. Changing rates of development in different types of retarded children sometimes appear due to changes in the developmental tasks facing the child, sometimes to changes in neurobiologic factors related to chronological age. Cross-domain findings from children of diverse etiologies suggest the necessity of certain, specific connections among seemingly disparate behaviors in development. The article concludes with a discussion of mental retardation research as an experiment of nature that serves to replicate and amplify existing findings as well as to spur new extensions of developmental theory.

Sixty male adjudicated juvenile delinquents between the ages 14–17, and 20 nondelinquent controls were administered measures of moral reasoning, social convention understanding, interpersonal awareness, socialization, empathy, autonomy, and psychopathy in an effort to explore the relations between moral reasoning, moral sentiment, and antisocial behavior. Not only did the delinquent group evidence developmental delays on all of these direct and indirect tests of morality functioning, but their performance on certain of these measures also differentiated those offenders who were more or less psychopathic. By demonstrating the special contribution of measures of moral will or sentiment to the study of antisocial behavior, these findings serve to underscore the multidimensional character of moral development, and the complexity of the relations between thought and action.

This article examines the frequency and stability of externalizing symptoms in a sample of 325 5-year-olds. Parent and teacher ratings, teacher nominations, parent-child interaction, and child measures were obtained. Using cutoff scores on teacher ratings, an average of 20% of the children were rated as having moderate externalizing problems in kindergarten and first grade. For both boys and girls, parent-teacher stability correlations ranged from .34–.45, and kindergarten teacher ratings from November and April correlated at .76. Instability in externalizing symptoms from kindergarten to first grade was related to a number of concurrent and previously assessed factors. For girls these included learning problems, shy-anxious behavior, mother-child interaction measures, and cognitive ability. Factors related to instability for boys included learning problems, social skills, cognitive ability, and self-control. These variables accounted for an additional 40% of the variance for boys (50% for girls) in first grade externalizing symptoms after controlling for externalizing symptoms in kindergarten.

A multidimensional study examined individual differences in observed behavior of 59 depressed mothers interacting with their 3–13-month-old infants in relation to selected demographic and psychosocial variables. Maternal competence–defined as sensitive, affectively appropriate maternal behavior, was positively related to maternal education, family income, and the number of hours mothers worked outside the home. Maternal competence was inversely related to life stress, marital discord, poor social support, and infant difficulty; all of these relations appeared to be mediated by the women's feelings of self-efficacy in the maternal role. A “risk index,” composed of noncorrelated variables (family income, hours per week mother worked outside the home, and maternal self-efficacy), was strongly related to maternal parenting competence. These results suggest that the quality of depressed mothers' behavior with their babies is related to self-evaluations and contextual risk or protective factors. The findings also highlight the heterogeneity in life circumstances and functioning of depressed women and the probable resulting variability in the level of functioning of their children.

Aggression observed in 2-year-old children of well and depressed mothers was examined in relation to problem behaviors at ages 5–6. Both normative (e.g., object struggles, rough play) and maladaptive (e.g., dysregulated, out-of-control behavior) forms of toddler aggression were identified. Dysregulated aggression predicted (a) externalizing problems reported by mothers when children were 5 years old, and (b) children's reports of difficulties during a structured psychiatric interview at age 6. Problems were more frequent and continuity patterns more evident in children of depressed, than well, mothers. Early maladaptive aggression was a better predictor of later externalizing, than internalizing problems. Childrearing practices of mothers of toddlers also appeared to contribute to later outcomes: negative influences were evident but protective patterns were present as well. Depressed mothers who used proactive childrearing approaches (e.g., anticipating the child's point of view; exerting modulated, respectful control; providing structure and organization during play environment) had children who showed fewer externalizing problems 3 years later.

The present study sought to examine two issues related to the phenomenological experience of depression in a normative sample of young, middle-school adolescents. The first hypothesis was that self-reported depressed affect would be highly related to low global self-worth. The second hypothesis was that depression is experienced as a blend of sadness and anger, where anger can be directed toward either the self or others. The findings revealed a strong correlation (r = .81) between global self-worth and affect (along a continuum of cheerful to depressed). With regard to the second issue, depression is clearly experienced by adolescents as a blend of affects. Eighty percent reported that depression represents a mix of sadness and anger. In addition, the vast majority reported that the anger is directed toward others, either as the only target or in conjunction with anger toward the self. Findings also revealed that the primary causes of depression involve actions of others against the self, thereby making the anger component realistic. Discussion focused on the role of self-deprecatory ideation in depression and on the issue of the comorbidity of internalizing and externalizing symptoms manifest in depression.

Two previous reports on a female population sample in Outer London, UK, had identified certain environmental experiences–such as lack of adequate replacement care after parental loss in childhood, premarital pregnancy, and low social class and poor emotional support in adulthood–as key factors intervening between childhood loss of parent and depression in adulthood. A third paper introduced a measure of the cognitive set of situational helplessness-mastery which was associated, on the one hand, with current depression and, on the other, with loss of mother in childhood. This article examines the relationship between these other factors and situational helplessness both in childhood and in adulthood. Most are highly associated with the cognitive set, but the relationship between childhood helplessness and loss of mother appears to be differentially mediated according to whether the loss was by death or separation. A series of multivariate statistical analyses aims to integrate all the findings so far reported on in this sample into a biographical model of the developmental pathways from childhood loss of mother to current depression.