Behavioural context and a distributed system: metabolic mapping studies of the basal ganglia.

Behavioural context is known to affect neural activity in the striatum. Responses of single cells increase to rewarding stimuli, or drop out as a bar press or saccade is learned. Networks that can accomplish a unique response to changing contexts are of particular interest to systems neuroscience and were a part of Hebb's interest in perception and learning. An overall map of the striatum that localizes changes related to this remarkable phenomenon of contextual responses contributes to our understanding of anatomical substrates of neural systems that integrate information, and may lead us to new striatal regions to study synaptic mechanisms of learning.     

Wildcat World: Simulation programs for teaching basic concepts in psychological science

A series of computer programs is described that allows beginning psychology students to design, conduct, analyze, and interpret virtual (computer-simulated) psychological studies. This technique allows the instructor more control over the outcome of student experiments, increases the scope of experiments that can be done by students, decreases the amount of class time that must be devoted to conducting experiments, and eliminates concerns about student experimenters using human or animal subjects.     

Scale-invariance as a unifying psychological principle

How can the classical psychological laws be explained and unified? It is proposed here that scale-invariance is a unifying principle. Distributions of many environmental magnitudes are observed to be scale invariant; that is, the statistical structure of the world remains the same at different measurement scales [Mandelbrot, B., 1982. The Fractal Geometry of Nature (2nd Edn.). W.H. Freeman, San Francisco, CA; Bak, P., 1997. How Nature Works: The Science of Self-organized Criticality. Oxford University Press, Oxford, UK]. We hypothesise that the perceptual-motor system reflects and preserves these scale invariances. This allows derivation of several of the most widely applicable psychological laws governing perception and action across domains and species (Weber's, Stevens', Fitts' and Piéron's Laws). We suggest that these fundamental laws reflect accommodation of the perceptuo-motor system to the scale-invariant physical world and therefore have a common foundation.     

Staying fit and staying well: physical fitness as a moderator of life stress

Previous research suggests that physical fitness moderates the adverse effects of stressful life events. However, a reliance on self-reports of fitness and health may limit the validity of prior investigations. The present research tested the stress-buffering effect of fitness with subjective and objective indicators of exercise, fitness, and physical well-being. For self-reports of health, both self-reports of exercise and objective measures of fitness showed the buffering effect; however, only objective fitness levels buffered stress when visits to a health facility were considered. Additional evidence indicated that this effect was largely independent of measures of psychological distress. Implications for understanding the link between fitness, stress, and health status are discussed.     

Informational masking and auditory attention.

Informational masking is broadly defined as a degradation of auditory detection or discrimination of a signal embedded in a context of other similar sounds; it is not related to energetic masking caused by physical interactions between signal and masker. In this paper, we report a systematic release from informational masking of a target tone in a nine-tone rapid auditory sequence as the target is increasingly isolated in frequency or intensity from the remaining sequence components. Improved target-tone frequency difference limens as isolation increases are interpreted as a reflection of increasingly focused auditory attention. The change from diffuse to highly focused attention is gradual over the frequency and intensity ranges examined, with each 1-dB increment in target intensity relative to the remaining components producing performance improvements equivalent to those produced by a 2% increase in frequency isolation. The results are modeled as bands of attention in the frequency and intensity domains. For attention directed by frequency isolation, there is a strong correspondence with auditory filters predicted by the power spectrum model of masking. These data also support the existence of an attention band of intensity, with a bandwidth of about 5-7 dB at the moderate levels used in this experiment.     

Believing the impossible

A version of this paper was read at the Western Division meetings of the APA in April 1990. I am indebted for the comments of my commentator on that occasion, Stephen Hetherington. I am also indebted to Ruth Marcus for helpful correspondence, and to Steven Luper-Foy for comments. Work on the paper was supported by an academic leave from Trinity University.     

Comparison of mediational selected strategies and sequential designs for preventive trials: Comments on a proposal by pillow et al.

Summary Mediational selection designs can increase the chance of finding an intervention to be statistically better than a control when compared to interventions applied to a selected subpopulation such as all children of divorce. Selection based on poor mediational variable scores creates a high expectation that many subjects will benefit because it matches a population to a given intervention strategy. It does not permit examination of the impact on other subjects nor the possibility of interventions that may be tuned to the specific needs of different subpopulations. A sequence of trials each built on the results of previous ones has the potential for extending the results obtained from a mediational selection design.     

Developmental epidemiologically based preventive trials: Baseline modeling of early target behaviors and depressive symptoms

Describes a conceptual framework for identifying and targeting developmental antecedents in early childhood that have been shown in previous work to predict delinquency and violent behavior, heavy drug use, depression, and other psychiatric symptoms and possibly disorders in late adolescence and into adulthood. Criteria are described that guided choices of targets for two epidemiologically based, randomized preventive trials carried out in 19 elementary schools in the eastern half of Baltimore, involving more than 2,400 first-grade children over the course of first and second grades. Baseline models derived from the first of two cohorts show the evolving patterns of concurrence among the target antecedents. The central role of concentration problems emerged. From Fall to Spring in first grade, concentration problems led to shy and aggressive behavior and poor achievement in both genders and to depressive symptoms among girls. There was evidence for reciprocal relationships in girls. For example, depressive symptoms led to poor achievement in both girls and boys, whereas poor achievement led to depressive symptoms in girls but not boys, at least over the first-grade year. These results provide important epidemiological data relevant to the developmental paths leading to the problem outcomes and suggest preventive trials.     

Progressive elaboration and memory for order in children

Three experiments were conducted investigating memory for items and order in a progressive elaboration paired-associates task. For all subjects retention of item information was improved by the use of progressively elaborated interactions relative to a no-elaboration control condition. For second and fourth graders, retention of order information depended upon the type of elaboration. If successive interactions were added in a logical temporal order, retention (of order information) was superior to the case where the successive interactions were added in a random order. This effect was not obtained with kindergarten children. In the second and third experiments, kindergarteners were instructed regarding the sequencing of the successive items, and results similar to those obtained with older children ensued. The data were discussed in terms of Tulving's distinction between episodic and semantic memory.