In this article we review information-processing studies applicable to the similar structure hypothesis. This hypothesis holds that when nonorganically impaired retarded and nonretarded persons are similar in general developmental level, they are also similar in the cognitive processes and concepts by which they reason. Results of this review were strikingly different from those of an earlier review focusing on Piagetian investigations. A meta-analysis revealed that the performance of retarded groups was significantly inferior to that of their nonretarded psychometric mental age peers. We also found a significant relation between the mental age of the subjects and the probability of finding a significant difference between retarded and nonretarded subjects. A number of alternative explanations are offered for these findings.

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As puppets are found in most every playroom, their relevance to play therapy is often taken for granted. This paper reviews the therapeutic value of puppets, detailing the psychological functions they can serve. Clinical technique--how to choose and use puppets--is addressed in both theoretical and practical terms.

To investigate the impact of low-level lead exposure on children's behavior within a natural setting, we assessed the school performance of a sample of 141 elementary school children classified according to dentine lead level. Twenty-two children had "elevated" levels (≥20 parts per million), 71 had "midrange" levels (10.0-19.9 parts per million), and 48 had "low" levels (<10 parts per million). Four types of outcome data were collected: (1) scores on a standardized group intelligence test, (2) teachers' ratings, (3) incidence of academic failure (assignment to remedial aid, grade retention), and (4) observations of classroom behavior. In general, higher dentine lead levels were associated with less favorable school performance, with most covariance-adjustedp-values in the range of 0.05-0.15. The incidence of grade retention was the outcome most strongly related to lead level. The pattern of results suggests a consistent, though weak relationship between children's dentine lead levels and elementary school performance.