To function effectively, individuals must voluntarily postpone immediate gratification and persist in goal-directed behavior for the sake of later outcomes. The present research program analyzed the nature of this type of future-oriented self-control and the psychological processes that underlie it. Enduring individual differences in self-control were found as early as the preschool years. Those 4-year-old children who delayed gratification longer in certain laboratory situations developed into more cognitively and socially competent adolescents, achieving higher scholastic performance and coping better with frustration and stress. Experiments in the same research program also identified specific cognitive and attentional processes that allow effective self-regulation early in the course of development. The experimental results, in turn, specified the particular types of preschool delay situations diagnostic for predicting aspects of cognitive and social competence later in life.

https://science.sciencemag.org/content/sci/244/4907/933.full.pdf

Delay of gratification in children

The present study used meta-analytic techniques to test whether trait consistency maximizes and stabilizes at a specific period in the life course. From 152 longitudinal studies, 3,217 test-retest correlation coefficients were compiled. Meta-analytic estimates of mean population test-retest correlation coefficients showed that trait consistency increased from .31 in childhood to .54 during the college years, to .64 at age 30, and then reached a plateau around .74 between ages 50 and 70 when time interval was held constant at 6.7 years. Analysis of moderators of consistency showed that the longitudinal time interval had a negative relation to trait consistency and that temperament dimensions were less consistent than adult personality traits.

http://jenni.uchicago.edu/Spencer_Conference/Representative%20Papers/Roberts%20&%20DelVecchio,%202000.pdf

The rank-order consistency of personality traits from childhood to old age: a quantitative review of longitudinal studies.

The present study used meta-analytic techniques (number of samples = 92) to determine the patterns of mean-level change in personality traits across the life course. Results showed that people increase in measures of social dominance (a facet of extraversion), conscientiousness, and emotional stability, especially in young adulthood (age 20 to 40). In contrast, people increase on measures of social vitality (a 2nd facet of extraversion) and openness in adolescence but then decrease in both of these domains in old age. Agreeableness changed only in old age. Of the 6 trait categories, 4 demonstrated significant change in middle and old age. Gender and attrition had minimal effects on change, whereas longer studies and studies based on younger cohorts showed greater change.

Patterns of mean-level change in personality traits across the life course: a meta-analysis of longitudinal studies.

Arthur Jensen argues that the failure of recent compensatory education efforts to produce lasting effects on children's IQ and achievement suggests that the premises on which these efforts have been based should be reexamined.

/pdf/how-much-can-we-boost-iq-and-scholastic-achievement-2dt4s2dafi.pdf

How Much Can We Boost IQ and Scholastic Achievement

Vulnerable periods during the development of the nervous system are sensitive to environmental insults because they are dependent on the temporal and regional emergence of critical developmental processes (i.e., proliferation, migration, differentiation, synaptogenesis, myelination, and apoptosis). Evidence from numerous sources demonstrates that neural development extends from the embryonic period through adolescence. In general, the sequence of events is comparable among species, although the time scales are considerably different. Developmental exposure of animals or humans to numerous agents (e.g., X-ray irradiation, methylazoxymethanol, ethanol, lead, methyl mercury, or chlorpyrifos) demonstrates that interference with one or more of these developmental processes can lead to developmental neurotoxicity. Different behavioral domains (e.g., sensory, motor, and various cognitive functions) are subserved by different brain areas. Although there are important differences between the rodent and human brain, analogous structures can be identified. Moreover, the ontogeny of specific behaviors can be used to draw inferences regarding the maturation of specific brain structures or neural circuits in rodents and primates, including humans. Furthermore, various clinical disorders in humans (e.g., schizophrenia, dyslexia, epilepsy, and autism) may also be the result of interference with normal ontogeny of developmental processes in the nervous system. Of critical concern is the possibility that developmental exposure to neurotoxicants may result in an acceleration of age-related decline in function. This concern is compounded by the fact that developmental neurotoxicity that results in small effects can have a profound societal impact when amortized across the entire population and across the life span of humans.

Critical periods of vulnerability for the developing nervous system: evidence from humans and animal models.

A developmental study of the behavior problems of normal children between twenty-one months and fourteen years

(1948). The Stability of Mental Test Performance Between two and Eighteen Years. The Journal of Experimental Education: Vol. 17, No. 2, pp. 309-324.

The Stability of Mental Test Performance Between two and Eighteen Years

Present and Past in Middle Life

A number of developmental studies have reported that the mental test scores of children under two years have little or no relationship to parental ability as measured by the number of years of schooling, ratings of intelligence, or test scores (I, 2, 6). When these same children are retested at later ages, their mental test scores are found to be significantly correlated with parental ability. A crucial question is the extent to which these age changes in relationship are due to environmental factors, or to intrinsic differences in the patterns of mental growth. One way in which this increasing resemblance can be evaluated is by comparing the age changes in the correlations which occur among children reared by their own parents in contrast to those reared apart from their parents.

Developmental studies of parent-child resemblance in intelligence.

The usefulness of psychological and pediatric appraisals of intelligence at 20 months in forecasting ability and achievement level at 10 years was explored for a time sample of 639 full-term children. The Cattell IQ was the best single predictor of IQ (r = .49) and achievement (r = .44) at age 10. A combination of Cattell IQ, pediatrician's rating, social quotient, perinatal-stress score, and parental SES yielded a multiple R of .58 with 10year IQ, with most of the added predictive power contributed by parental SES. For children with Cattell IQ's below 80, a combination of infant-test scores and pediatricians' ratings of intelligence yielded a multiple R of .80 with 10-year IQ. The majority of children scoring low on the Cattell or the pediatricians' ratings of intelligence at 20 months had serious schoolachievement problems at 10.

Marjorie P. Honzik

Papers

A developmental study of the behavior problems of normal children between twenty-one months and fourteen years

The Stability of Mental Test Performance Between two and Eighteen Years

Present and Past in Middle Life

Developmental studies of parent-child resemblance in intelligence.

Prediction of intelligence and achievement at ten years from twenty months pediatric and psychologic examinations.