Nonlinear visuomotor transformations: locus and modularity

Participants in two experiments moved a mouse-like device to the right to move a cursor on a computer screen to a target position. The cursor was invisible during motion but reappeared at the end of each movement. The relationship between the amplitudes of the cursor movement and the mouse movement was exponential in Experiment 1 and logarithmic in Experiment 2 for two groups of participants, while it was linear for the control groups in both experiments. The results of both experiments indicate that participants adjusted well to the external transformation by developing an internal model that approximated the inverse of the external transformation. We introduce a method to determine the locus of the internal model. It indicates that the internal model works at a processing level that either preceded specification of movement amplitude, or had become part of movement amplitude specification. Limited awareness of the nonlinear mouse-cursor relationship and the fact that a working-memory task had little effect on performance suggest that the internal model is modular and not dependent on high-level cognitive processes.     

Cognitive style and learning: performance of adaptors and innovators in a novel dynamic task

The influence of cognitive style on performance in a novel dynamic task modelled on the task of controlling air traffic was investigated. It was hypothesized that participants who preferred a more adaptive cognitive style would maintain better rule adherence and safe distances between aircraft in a low‐fidelity air traffic control task than those who preferred a more innovative style. Problems were presented to participants using computer‐based scenarios in screening, practice, and experimental trials. Performance was measured by the number of times the participant violated two types of scenario rules. Screening, practice, and experimental performance were analysed separately. Cognitive style had a significant effect on performance only during experimental trials. Performance of individuals who preferred a more adaptive style improved across experimental trials while those preferring a more innovative style did not. Results suggest that the more innovative participants, although perhaps having some initial advantage, may not be able to sustain performance in this type of task. Published in 2001 by John Wiley & Sons, Ltd.     

Modeling individual differences in working memory performance: a source activation account

Working memory resources are needed for processing and maintenance of information during cognitive tasks. Many models have been developed to capture the effects of limited working memory resources on performance. However, most of these models do not account for the finding that different individuals show different sensitivities to working memory demands, and none of the models predicts individual subjects' patterns of performance. We propose a computational model that accounts for differences in working memory capacity in terms of a quantity called source activation , which is used to maintain goal-relevant information in an available state. We apply this model to capture the working memory effects of individual subjects at a fine level of detail across two experiments. This, we argue, strengthens the interpretation of source activation as working memory capacity.     

A Debate on the Ethics of Aging: Does the Concept of Autonomy Provide a Sufficient Framework for Aging Policy?

This article presents a debate on the issue of autonomy in aging policy held at the 1994 annual meeting of the American Society on Aging held in San Francisco, California. Harry R. Moody, director of the Institute for Human Values in Aging at Hunter College, supports a reconceptualized notion of personal autonomy which focuses on issues of power, theory, and practice, and finds conflicts between autonomy and justice in the lived world of the elderly and disabled. In aging policy, he promotes an emphasis on social movements such as Hospice rather than on autonomy of individuals. He suggests alternatives to extreme paternalism or complete autonomy, such as a communicative ethics approach. Larry Polivka, director of the Florida Policy Exchange Center on Aging at the University of South Florida, affirms that policy for the aging and disabled should be based ona commitment to autonomy. He describes an integrated model for long-term care that places autonomy first and includes features of communicative ethics and the negotiated consent and virtues models of ethics.