Book reviews

The Supernatural, the Occult and the Bible. Gerald A. Larue Buffalo, New York: Prometheus Books, 1990. 303 pp. £1355

My Dad's Hindu, my Mum's Side are Sikhs: Issues in Religious Identity Eleanor Nesbitt Oxford: The National Foundation for Arts Education, in collaboration with Warwick University, 1991. 47 pp. £ 450

God East and West Michael Barnes London: SPCK, 1991. 138 pp. £7.99     

Limb apraxia and motor performance

This study was desinged to determine if motor deficits in limb apraxia are task specific. Non-brain-damaged patients and apraxic and nonapraxic patients with left hemisphere damage performed language and limb apraxia tests and six motor tasks with the left hand. Contrary to previous data, no significant group differences occurred on a finger tapping task. Although task complexity or sequencing requirements affected group differences, greatest apraxic impairment was noted on a task of precise steadiness, but only when its response inhibition requirements were increased. This pattern of deficits appears to be associated with greater involvement of the premotor area in the apraxic group.     

Psychometric and CT scan measurements in a case of crossed aphasia in a dextral

A case of crossed aphasia with lesion deep to the right supramarginal gyrus was studied to determine (1) if this patient behaved similar to patients with the same lesion site in the left hemisphere, (2) if visuospatial deficits were present, and (3) if the CT scan asymmetries were similar to those of other right-handers. Speech and language skills were similar to those patients with similar lesions in the left hemisphere. Visuospatial and arithmetic deficits were similar to those described after right-hemisphere and left-hemisphere damage. CT scan asymmetries were atypical. These results provide behavioral and neuroradiological confirmation of atypical hemispheric dominance.     

Genes Determine Stability and the Environment Determines Change in Cognitive Ability During 35 Years of Adulthood

ABSTRACT— Previous research has demonstrated stability of cognitive ability and marked heritability during adulthood, but questions remain about the extent to which genetic factors account for this stability. We conducted a 35-year longitudinal assessment of general cognitive ability using the Armed Forces Qualification Test administered to 7,232 male twins in early adulthood and readministered to a subset of 1,237 twins during late middle age. The proportion of variance in cognitive functioning explained by genetic factors was .49 in young adulthood and .57 in late middle age. The correlation between the two administrations was .74 with a genetic correlation of 1.0, indicating that the same genetic influences operated at both times. Genetic factors were primarily responsible for stability, and nonshared environmental factors were primarily responsible for change. The genetic factors influencing cognition may change across other eras, but the same genetic influences are operating from early adulthood to late middle age.     

Inferring interventional predictions from observational learning data

Previous research has shown that people are capable of deriving correct predictions for previously unseen actions from passive observations of causal systems (Waldmann & Hagmayer, 2005). However, these studies were limited, since learning data were presented as tabulated data only, which may have turned the task more into a reasoning rather than a learning task. In two experiments, we therefore presented learners with trial-by-trial observational learning input referring to a complex causal model consisting of four events. To test the robustness of the capacity to derive correct observational and interventional inferences, we pitted causal order against the temporal order of learning events. The results show that people are, in principle, capable of deriving correct predictions after purely observational trial-by-trial learning, even with relatively complex causal models. However, conflicting temporal information can impair performance, particularly when the inferences require taking alternative causal pathways into account.     

Seeing versus doing: two modes of accessing causal knowledge

The ability to derive predictions for the outcomes of potential actions from observational data is one of the hallmarks of true causal reasoning. We present four learning experiments with deterministic and probabilistic data showing that people indeed make different predictions from causal models, whose parameters were learned in a purely observational learning phase, depending on whether learners believe that an event within the model has been merely observed ("seeing") or was actively manipulated ("doing"). The predictions reflect sensitivity both to the structure of the causal models and to the size of their parameters. This competency is remarkable because the predictions for potential interventions were very different from the patterns that had actually been observed. Whereas associative and probabilistic theories fail, recent developments of causal Bayes net theories provide tools for modeling this competency.