617 adults and children served as Ss in 9 studies of the relation between expressed preference and differing amounts of variability of stimulation. Random shapes and different sequential approximations to English were used as variations in stimulus variability. The results supported the following generalizations. Human beings arc sensitive to amount of variability in stimulation. There is an intermediate amount of variability which was consistently most preferred by unsophisticated Ss. Preference for the stimuli used was jointly determined by number of independent characteristics of the stimuli and their meaningfulness. Preference for variability changed with Ss' experience with variable stimulation, whether the experience was induced experimentally or was the result of specific professional training. The tendency to increase preference for stimulation of high variability is related to Ss' ability to code or process variability.
This review summarizes all reliable published data about the nature and nurture of adopted children's IQs and draws conclusions about the relative importance of heredity and environment on children's mental development.Any study that compares the central tendency of adopted children's IQs with a group mean of 100 IQ points for a normal population cannot be taken seriously until several methodological criteria have been met: (a) representative sampling, (b) no differential loss of subjects over time, (c) accurate, age-corrected information on biological and adoptive parents, (d) careful attention to early separation and placement of children, and (e) elimination of practice effects and regression to the mean artifacts. Existing adoption studies that rely on group average comparisons are flawed by the biased sampling and other methodological problems that they all contain. On the other hand, some firm conclusions can be drawn from the resemblance between individual adopted children's IQ scores and their adoptive and biological parents' mental abilities. Analysis shows that the adoptive parents' home environment has only a modest effect on their adopted children's intellectual growth (r = .19 for 351 families), while the heredity and environment of the biological parents have a strong effect on their own children's intellectual growth (r = .58, n = 378 families). At present there is disagreement about the precise values of genetic and environmental effects on IQ, and several assumptions must be made before accurate statistics can be derived. But, the available data strongly suggest that under existing circumstances, heredity is much more important than environment in producing individual differences in IQ.After L. F. Richardson (1912-13) pro-adopted children and compared their scores posed the use of adopted x children to study with various groups to determine whether the nature and nurture of IQ, many investi-genetic or environmental factors exert more gators measured the mental development of influence on cognitive development. A mass of adoptive evidence on the nature-nurture Requests for reprints should be sent to Harry issue has accumulated within the last half Munsinger,
Newborn humans presented with pairs of shapes, each shape differing in number of turns (angles), prefer shapes with 10 turns to shapes with 5 turns or 20 turns, as inferred from photographic recordings of eye fixations.
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