Individuals with an autism spectrum disorder (ASD) are thought to encounter planning difficulties, but experimental research regarding the mastery of planning in ASD is inconsistent. By means of a meta-analysis of 50 planning studies with a combined sample size of 1755 individuals with and 1642 without ASD, we aim to determine whether planning…

Responds to "Birth Order and Intelligence: Further Tests of the Confluence Model" by Robert D. Retherford and William H. Sewell. Reviews their arguments and suggests that their analyses of the Wisconsin Longitudinal Study data support rather than contradict the model. (CJS)

Studies comparing the strengths and weaknesses of intellectually retarded and superior groups are reviewed, with particular attention given to studies in which these extreme groups were matched with each other on mental age. (Author)

Persons representing the extremes of intelligence cannot be included in the same study unless they are approximately equated on mental age, in which case the relative performances of the extreme groups can provide useful information about the nature of intelligence. (Author/RD)

Reviews the major contributions of Alfred Binet. Explains why the fame of the Binet-Simon Intelligence Scale was so long lasting whereas that of his other contributions was so fleeting. Discusses implications of his contributions for current efforts to formulate unified theories of cognition and cognitive development. (Author/GLR)

Surveys 30 studies involving 104 separate tests of the "similar structure hypothesis" which holds that, when nonorganically impaired retarded and nonretarded persons are similar in developmental level, they are also similar in the processes and concepts by which they reason. (Researchers distinguished between studies that excluded…

Confluence theory was developed to explain the negative effects of birth order on intelligence. Using aggregate, between-family, within-family, and paired-sibling data from the Wisconsin Longitudinal Study, tests the mathematical form of confluence theory and finds no support for it. Suggests that statistical methods used to fit the model to the…

The literature on the moral judgment and moral development of mentally retarded individuals is reviewed. The relative contribution of mental age, chronological age, cognitive functioning, social experience, and environmental factors to the moral characteristics of this population is discussed. (Author/RM)

The intellectual model of Jean Piaget asserts that individuals pass through a series of various intellectual stages as they mature. Human development is categorized into four basic stages: (1) sensory motor stage, which lasts from birth to about eighteen months; (2) preoperational stage, lasting from eighteen months to about seven years; (3)…