COMT val158Met and executive control: a test of the benefit of specific deficits to translational research

The role of catechol-O-methyltransferase (COMT) val158met in prefrontal cortical deficits associated with the liability to schizophrenia remains controversial. This study evaluated 464 healthy adult participants using three measures of executive functions in working memory: a 3-back version of the N-back continuous performance task (CPT) and two variants of the AX-CPT. The interpretability of N-back performance was confounded by possible generalized deficits, whereas the AX variants included internal controls for uncovering specific deficits. There was no relationship between the COMT genotype and N-back performance, whereas val/val individuals had a specific deficit on a dot-pattern version of the AX-CPT. In this case, a specific executive function known as context processing appeared to be compromised. These data suggest that the interpretability gained by including task manipulations to uncover specific deficits can enhance associations between cognitive and genetic levels of analysis.     

Initiation of Reflective Frames in Counseling for Huntingtons Disease Predictive Testing

Genetic professionals and clients are likely to assign different meanings to the extended format of the counseling protocols for predictive testing. In order to facilitate informed, client-centered decisions about the possibility of predictive testing, counselors routinely use the question format to initiate what we call "reflective frames" that invite clients to discuss their feelings and encourage them to adopt introspective and self-reflective stances toward their own experience--spanning the past, the present, and the hypothetical future. We suggest that such initiations of reflective frames constitute a key element of counselors' nondirective stance, although the exact nature of their formulations can be complex and varied. Examining 24 Huntington's Disease (HD) clinic sessions involving 12 families in South Wales with the tools of discourse analysis, our focus in this paper is twofold: (i) to propose a classification of six types of reflective questions (e.g. nonspecific invites, awareness and anxiety, decision about testing, impact of result, dissemination, and other) and to examine their distribution across the various clinic appointments, and (ii) to investigate the scope of these questions in terms of temporal and social axes. We link our analysis to the current debate within the genetic counseling profession about the merits of reflection- versus information-focused counseling styles and the need to abide by professionally warranted and institutionally embedded counseling protocols.     

What is being masked in object substitution masking?

Object substitution masking (OSM) is said to occur when a perceptual object is hypothesized that is mismatched by subsequent sensory evidence, leading to a new hypothesized object being substituted for the first. For example, when a brief target is accompanied by a longer lasting display of nonoverlapping mask elements, reporting of target features may be impaired. J. T. Enns and V. Di Lollo (2000) considered it an outstanding question whether OSM masks some or all aspects of a target. The authors report three experiments demonstrating that OSM can selectively affect target features. Participants may be able to detect a target while being unable to report other aspects of it or to report the color but not the orientation of a target (or vice versa). We discuss these findings in relation to two other visual phenomena.     

Event-related FMRI study of context processing in dorsolateral prefrontal cortex of patients with schizophrenia

Context processing is conceptualized as an executive function involved in voluntary, complex actions such as overcoming automatic responses. The present study tested the hypothesis that context-processing deficits in patients with schizophrenia are associated with a dysfunction of left dorsolateral prefrontal cortex (DLPFC). Using event-related functional magnetic resonance imaging (fMRI), 17 controls and 17 medicated patients performed a version of the AX task in which a learned, automatic response had to be inhibited. In controls, left DLPFC activity increased when preparing to overcome an automatic response, whereas patients with schizophrenia showed no differential activation. In controls, context processing appeared to be associated with the differential representation of cues associated with the need to provide top-down support for overcoming automatic responses. This mechanism appeared to be impaired in patients with schizophrenia.     

Response inhibition can affect reaction time to abrupt-onset visual displays

Reaction time (RT) to abrupt-onset stimuli has been widely used for more than a century to measure the duration of perceptuo-cognitive and motor processes [Donders, 1868/1969 Attention and Performance II (1969 Acta Psychologica 30 412-431)]. A complicating factor with the RT method is that of response withholding, or response inhibition (RI). The occurrence of RI (under this or other names) has been widely discussed in relation to studies of motor processes but has been largely ignored in relation to studies of perceptuo-cognitive processes. We demonstrate that RI can be a confounding factor when RT to abrupt-onset displays is used to study perceptual and cognitive processes. In experiment 1, new-object targets were more accurately detected than old-object targets in an unspeeded task, but were responded to more slowly in an RT task. Consistent with an interpretation in terms of RI, this pattern of results was dependent on the difficulty of target detection. The data of three further experiments also support predictions from the RI interpretation. It is suggested that RI may be an under-acknowledged factor in RT studies of perceptual and cognitive processes with abrupt-onset displays.     

Model Fit and Item Factor Analysis: Overfactoring,Underfactoring, and a Program to Guide Interpretation

In exploratory item factor analysis (IFA), researchers may use model fit statistics and commonly invoked fit thresholds to help determine the dimensionality of an assessment. However, these indices and thresholds may mislead as they were developed in a confirmatory framework for models with continuous, not categorical, indicators. The present study used Monte Carlo simulation methods to investigate the ability of popular model fit statistics (chi-square, root mean square error of approximation, the comparative fit index, and the Tucker–Lewis index) and their standard cutoff values to detect the optimal number of latent dimensions underlying sets of dichotomous items. Models were fit to data generated from three-factor population structures that varied in factor loading magnitude, factor intercorrelation magnitude, number of indicators, and whether cross loadings or minor factors were included. The effectiveness of the thresholds varied across fit statistics, and was conditional on many features of the underlying model. Together, results suggest that conventional fit thresholds offer questionable utility in the context of IFA.     

Book reviews

Gelman, R. and Gallistel, C. R. The Child's understanding of Number. Cambridge, Mass.: Harvard University Press. 1978. Pp. 260. ISBN 0 674 11636 4. £9.45.

Boden, M. A. Piaget. London: Fontana. 1979. Pp. 174. ISBN 000 635537 4. £1.25.

Vygotsky, L. S. Mind in Society. Cambridge, Mass: Harvard University Press. 1979. Pp. 159. ISBN 0 674 57628 4. $12.50.

Catania, A. Charles. Learning. Englewood Cliffs, N.J.: Prentice-Hall. 1979. Pp. xi + 406. ISBN 0 13 527432 X. $16.95 £11.00.

Kagan, J., Kearsley, R. B. and Zelazo, P. R. Infancy: Its place in Human Development. Second edition. Cambridge, mass.: Harvard University Press. 1979. Pp. 462. ISBN 0 674 45260 7. $17.50.

Shaffer, D. and Dunn, J. (Eds). The First Year of Life: Psychological and Medical Implications of Early Experience. Chichester: Wileys. 1979. Pp. 221. ISBN 0 471 99734 X. £11.80.     

Book reviews

Thomassen, A., Keuss, P. and van Galen, G. (Eds.). Motor aspects of handwiriting. Amsterdam: North-Holland. 1984. Pp 354. ISBN 0444-86774-0. $50.

Klatskyk, R. L. Memory and awareness. New York: W. H. Freeman. 1984. Pp. 155. ISBN 0-7167-1600-3. £9.95.

Longman Dictionary of Psychology and Psychiatry. New York: Longman. 1984. ISBN 0-582-28257, pp 816, £46.00.

Kintsch, W., Miller, J. R., and Polson, P. G. Methods and tactics in cognitive seience. Hilisadale, N.J.: Lawrence Erlbaum Associates. 1984. Pp. xii+324. ISBN 0-89859-372-1. £27.50.

Dubery, F. and Williats, J. Perspective and other drawing systems. London: The Herbert Press. 1983. Pp. 128. ISBN 0-906969 -25-5. £4.95.

Morris, P. E. and Hampson, P. J. Imagery and consciousness. London: Academic Press. 1983. Pp. 341. ISBN 0-12-507680-0. $36.50.

Bundy, A. The computer modelling of mathematical reasoning. London: Academic Press. 1983. Pp. 322. ISBN 0-12-141252-0. $15.00.

Jeeves, M. A. and Greer, G. B. Analysis of structural learning. London: Academic Press. 1983. Pp. 265. ISBN 0-12-382080-4. $40.00.

Taylor, I. and Taylor, M. M. The psychology of reading. New York: Academic Press, 1983. Pp. 511. ISBN 0-12-684080-6 $29.50.

Wade, N. J. (Ed.). Brewster and Wheatstone on vision. London: Academic Press. 1984. Pp. 358. ISBN 0-12-729550-X. $39.00.

Harre, R. and Lamb, R. The encyclopedic dictionary of psychology. Oxford: Blackwell. 1983. ISBN 0-631-12663-5. £55.00.

Kail, R. and Spear, N. E. (Eds.). Comparative perspectives on the development of memory. Hillsdale, N. J.: Lawrence Erlbaum Associates. 1984. Pp. x+ 374. ISBN 0-89859-317-4. £37.50.

R. Hockey (Ed.). Stress and fatigue in human performance. London: Wiley. 1983. ISBN 0-471 10-265-2. £16.50.

Sarris, V. and Parducci, A. (Eds.). Perspectives in psychological experimentation: Toward the year 2000. Hillsdale, N. J.: Lawrence Erlbaum Associates. 1984. Pp. 370. ISBN 0-89859-272-9. £33.30.