Asymmetries in the discrete and pseudocontinuous regulation of visually guided reaching.

An experiment was conducted to examine the contribution of the hemispheres to the organization of aiming movements. The spatial positions of targets were obtained by extrapolating from brief visual displays of geometric patterns. The patterns comprised linear, quadratic, cubic, and quartic mathematical functions and varied in spatial complexity. Vision of the hand was also manipulated. While the hands did not differ in spatial accuracy, movements made by the right hand were of shorter duration and had higher peak velocities. The stimulus pattern strongly influenced kinematics, in particular the number of discrete modifications of the movement trajectory. Vision of the hand resulted in superior accuracy, although subjects were unable to compare the relative positions of the limb and the target. Vision of the hand did not lead to an increase in discrete adjustments, suggesting that visual information was used in a continuous fashion. Movements into ipsilateral space differed from those into contralateral space with respect to a number of parameters.     

Book reviews

Campbell, B. A., Hayne, H., & Richardson, R. (Eds.) (1992). Attention and information processing in infants and adults. Perspectives from human and animal research. Hove: Lawrence Erlbaum Associates. Pp. viii + 360. ISBN 0-8058-0782-9. £54.95 (Hbk).

McFarland, D. (1993). Animal behaviour: Psychobiology, ethology and evolution (2nd ed.). Harlow: Longrnan Scientific and Technical. Pp. xiv + 585. ISBN 0-582-06721-9. £23.99 (Pbk).

Ward, J. P., & Hopkins, W.D. (Eds.) (1993). Primate laterality: Current behavioral evidence of primate asymmetries. New York/Berlin: Springer-Verlag. Pp. xii + 356. ISBN 0-387-97961-1 13-540-97961-1. £34.50 (Pbk).

Zentall, T. R. (Ed.). (1993). Animal cognition. A tribute to Donafd A. Riley. Hillsdale, NJ: Lawrence Erlbaum Associates, Inc. Pp. xiv + 369. ISBN 0-8058-1 184-2. £22.95 (Pbk); ISBN 0-8058-1 183-4. £53.50 (Hbk).

Roitblatt, H. L., Herman, L. M., & Nachtigall, P.E. (Eds.) (1993). Language and communication. Comparative perspectives. Hillsdale, NJ : Lawrence Erlbaum Associates, Inc. Pp. xvi + 502. ISBN 0-8058-0947-3. £26.95 (Pbk); ISBN 0-8058-0946-5. £59.95 (Hbk).

Bradshaw, J. L, & Rogers, L.J. (1993). The evolution of lateral asymmetries, language, roo1 use, and intellect. San Diego, CA: Academic Press. Pp. xiii + 463. ISBN 0-12-124560-8. £58.00 (Hbk).

Ten Cate, C., Slater, P. J. B., & Kruijt, J. P. (Eds.) (1993). Song learning and imprinting. An inquiry into mechanisms of behavioural development. Amsterdam: Netherlands Zoology Society. Pp. 234. £13.00 (Pbk).     

Imitation from 12 to 24 months in autism and typical development: a longitudinal Rasch analysis

The development of imitation during the second year of life plays an important role in domains of sociocognitive development such as language and social learning. Deficits in imitation ability in persons with autism spectrum disorder (ASD) from toddlerhood into adulthood have also been repeatedly documented, raising the possibility that early disruptions in imitation contribute to the onset of ASD and the deficits in language and social interaction that define the disorder. This study prospectively examined the development of imitation between 12 and 24 months of age in 154 infants at familial risk for ASD and 78 typically developing infants who were all later assessed at 36 months for ASD or other developmental delays. The study established a developmental measure of imitation ability and examined group differences over time, using an analytic Rasch measurement model. Results revealed a unidimensional latent construct of imitation and verified a reliable sequence of imitation skills that was invariant over time for all outcome groups. Results also showed that all groups displayed similar significant linear increases in imitation ability between 12 and 24 months and that these increases were related to individual growth in both expressive language and ratings of social engagement but not in fine motor development. The group of children who developed ASD by age 3 years exhibited delayed imitation development compared with the low-risk typical outcome group across all time-points, but were indistinguishable from other high-risk infants who showed other cognitive delays not related to ASD.     

Transformations of mathematical and stimulus functions

Following a pretest, 8 participants who were unfamiliar with algebraic and trigonometric functions received a brief presentation on the rectangular coordinate system. Next, they participated in a computer-interactive matching-to-sample procedure that trained formula-to-formula and formula-to-graph relations. Then, they were exposed to 40 novel formula-to-graph tests and 10 novel graph-to-formula tests. Seven of the 8 participants showed substantial improvement in identifying formula-to-graph relations; however, in the test of novel graph-to-formula relations, participants tended to select equations in their factored form. Next, we manipulated contextual cues in the form of rules regarding mathematical preferences. First, we informed participants that standard forms of equations were preferred over factored forms. In a subsequent test of 10 additional novel graph-to-formula relations, participants shifted their selections to favor equations in their standard form. This preference reversed during 10 more tests when financial reward was made contingent on correct identification of formulas in factored form. Formula preferences and transformation of novel mathematical and stimulus functions are discussed.     

MMPI-2 at the crossroads: aging technology or radical retrofitting?

Paradigmatic shifts are uncommon in psychological assessment, which is often steeped more in tradition than innovative practices. The introduction of the Restructured Clinical (RC) Scales by Tellegen et al. (2003) represents a radical shift in the development and validation of the MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989). In broadening the debate over the merit of the RC Scales, in this article, we examine current challenges to MMPI-2 interpretation including issues with discriminant validity and imprecision (e.g., standard errors of measurement).We evaluate the RC alternative in the context of these interpretive challenges. Although we note several improvements, the incremental validity for MMPI-2 interpretative statements remains to be established. MMPI-2 researchers may wish to test several innovative models for their comparative strengths in establishing scale properties and providing empirically based interpretations.