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Nonshared environmental influences have consistently been shown to account for at least as much of the variance in personality as genetic factors, but the nature of these nonshared influences has largely remained unidentified. To identify environmental predictors of differential personality development, the Personality Research Form and 4 measures of people's perceptions of their background environments were administered to 143 adult twin pairs (93 monozygotic [MZ] and 50 dizygotic [DZ]) and 66 pairs of same-sex nontwin (NT) siblings. Differences between MZ twins, DZ twins, and NT siblings in a number of dimensions of personality were significantly related to differences on the environmental measures, and phenotypic correlations between the personality and environment measures were themselves entirely attributable to correlated nonshared environmental effects.

The evaluation of dynamic spatial performance and general intelligence in a group of 94 university students reveals that dynamic spatial measure, despite the link to performance, does not load performance IQ. The dynamic spatial measure is determined by the number of times a moving target is hit. The number of hits is correlated with performance IQ, but not with verbal IQ.

Abstract Background Although significant response time deficits (both reaction time and movement time) have been identified in numerous studies of patients with Parkinson's disease (PD), few attempts have been made to evaluate the use of these measures in screening for PD. Methods Receiver operator characteristic curves were used to identify cutoff scores for a unit-weighted composite of two choice response tasks in a sample of 40 patients and 40 healthy participants. These scores were then cross-validated in an independent sample of 20 patients and 20 healthy participants. Results The unit-weighted movement time composite demonstrated high sensitivity (90%) and specificity (90%) in the identification of PD. Movement time was also significantly correlated (r = 0.59, p < 0.025) with the motor score of the Unified Parkinson's Disease Rating Scale (UPDRS). Conclusions Measures of chronometric speed, assessed without the use of biomechanically complex movements, have a potential role in screening for PD. Furthermore, the significant correlation between movement time and UPDRS motor score suggests that movement time may be useful in the quantification of PD severity.

The paper describes recent research investigating the relationship between speed with which individuals can execute basic cognitive processes and performance on tests of intelligence and mental ability. Results are discussed in terms of three properties of the working-memory system which limit the amount of information for simultaneous storing and processing. (Author/CL)

Longstreth's critique of Jensen's research on the relationship of IQ to individual differences in visual reaction time (RT), measured in the Hick paradigm, is said to have numerous errors of fact and interpretation, some trivial and some of theoretical importance. (Author/LMO)

Ruchalla, Schalt, and Vogel (1985) reported a negative correlation between the g-loadness of intelligence subtests and the extent to which the subtests correlated with reaction times. Possible methodological problems with Ruchalla et al. are described, and results of two other studies pertinent to the issue are discussed. (Author/LMO)

To assess the effects of timed/untimed testing conditions on intelligence scores, high school students were assigned to an intelligence test under either conditions and subsequently to a battery of eight reaction time tests. Results showed that subjects scores were related to the speed with which they processed information. (JAZ)

Eighty-one university students were given a battery of reaction time tests and a group test of intelligence which yielded timed and untimed scores. Multiple regression analyses indicated that speed of information-processing was an equally good predictor of timed and untimed intelligence test performance. (Author/LMO)