Testing for symmetry in the conditional discriminations of language-trained chimpanzees

If subjects are taught to match Stimulus A to B and then, without further training, match B to A, they have passed a test of symmetry. It has been suggested that non-humans' lack of success on symmetry tests might be overcome by giving them a history of symmetry exemplar training, that is, by directly teaching a large number of conditional relations (e.g., AB, CD, EF,...) and also directly training the "reverse" of these relations (e.g., BA, DC, FE,...). The chimpanzee subjects of the present study, Sherman, Austin, and Lana, had already received extensive symmetry exemplar training as a result of attempts to teach a selection-based language system of lexigrams. The present study systematically subjected 2 of these chimps (Sherman and Lana), for the first time, to standard symmetry tests in controlled conditions. Both chimps failed the tests, even when their correct responses on test trials were reinforced. The findings do not support the exemplar training hypothesis, and cast doubt upon whether the chimps can pass tests of stimulus equivalence.     

Unreinforced Conditional Selection by Two-Year-Olds in A Six-Comparison Matching Task

The Psychological Record - Four normally developing 2-year-old children were exposed to a story in which six novel characters appeared and were named. To assess learning of the character name...     

Factors influencing school achievement of children from low socioeconomic groups in Malaysia(1)

A general model is proposed relating the social and nutritional factors involved in school performance of children from poor socio-economic backgrounds. The model has been tested in a group of 263 primary school children who came from mainly lower-class families in Malaysia. School performance was assessed by the mark in a national school examination; the factors considered were race, sex, type of school attended, nutritional status and score in the Goodenough-Harris Draw-a-Man test, and also the family size, income and education of parents. Multiple linear regression and extended median test were used in the analysis. There were strong associations between poor school performance on the one hand and nutritional and socio-economic conditions on the other. However, detailed analysis showed that, for most sub-groups, nutritional status was not a direct causal factor in school performance. Both nutrition and school achievement reflected home circumstances, particularly family income. There were however significant differences among children of different races. Many of the pathways on the general model have been shown to be irrelevant in this group of children; those pathways which remain are likely to be causal. The Goodenough-Harris test showed highly significant differences between children of different ethnic groups. The general model seems justified as a framework for investigating school performance. It has been shown that simple correlation between factors is not a good guide to cause-and-effect relationships. Each deprived group is likely to have its own significant pathways, so that each group should be analysed rather than applying generalisations derived from other populations.