Frontal lobe dysfunction and memory impairment in patients with chronic progressive multiple sclerosis

Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly.     

Forecasting the impact of the federal sentencing guidelines

The Sentencing Reform Act of 1984, which created the U.S. Sentencing Commission, required that the commisson consider prison capacity in drafting sentencing guidelines. As part of the commission's efforts to meet this requirement, we developed a computer simulation capable of projecting the impact of the commission's guidelines on future sentences and prison populations. According to our projections, “straight” probation sentences will be reduced significantly under the guidelines. However, reducing the use of probation will generate only modest demands on the prisons, and then mostly for community corrections phased in over the course of 5 years. We also project that, while average time served for violent offenses will increase substantially, average time served for most property crimes will remain largely the same. Finally, while we forecast that federal prison populations will grow markedly by the end of this century, this is more a result of the Anti-Drug Abuse Act of 1986 and the career offender provision of the Comprehensive Crime Control Act of 1984 than a result of the guidelines.     

Song frequency as a cue for recognition of species and individuals in the field sparrow (Spizella pusilla)

Estimate the amount of frequency variation that affected individual and species recognition by song in territorial male field sparrows with field playbacks of neighbors' songs lowered in frequency in 6 increments between 324 and 1296 Hz. Males gave strong responses to neighbors' songs that had been lowered by about 400 Hz, which is about 11% of the mean midfrequency in field sparrow song. Territorial responses were eliminated when neighbors' songs were lowered by more than about 900 Hz. Thus, there is a fairly narrow range of frequencies within which field sparrow songs can vary while functioning in communication. Ss' responses appear to be constrained by the normal range of song frequency variation within the species, but the range of variability within songs of individuals did not influence the degree of frequency shift required to render neighbors' songs unfamiliar.     

Automation of learning-set testing: The video-task paradigm

Researchers interested in studying discrimination learning in primates have typically utilized variations in the Wisconsin General Test Apparatus (WGTA). In the present experiment, a new testing apparatus for the study of primate learning is proposed. In the video-task paradigm, rhesus monkeys (Macaca mulatta) respond to computer-generated stimuli by manipulating a joystick. Using this apparatus, discrimination learning-set data for 2 monkeys were obtained. Performance on Trial 2 exceeded 80% within 200 discrimination learning problems. These data illustrate the utility of the video-task paradigm in comparative research. Additionally, the efficient learning and rich data that were characteristic of this study suggest several advantages of the present testing paradigm over traditional WGTA testing.     

A controlled comparative investigation of psychological treatments for chronic sleep-onset insomnia

A sample of physician-referred chronic insomniacs was randomly allocated to either progressive relaxation, stimulus control, paradoxical intention, placebo or no treatment conditions. Treatment process and outcome were investigated in terms of mean and standard deviation (night to night variability) measures of sleep pattern and sleep quality. Only active treatments were associated with significant improvement, but the nature of treatment gains varied. In particular, stimulus control improved sleep pattern, whereas relaxation affected perception of sleep quality. All improvements were maintained at 17 month follow-up. Results are discussed with reference to previous research and guidelines are given for clinical practice.     

Testing between the TRACE model and the fuzzy logical model of speech perception

The TRACE model of speech perception (McClelland & Elman, 1986) is contrasted with a fuzzy logical model of perception (FLMP) (Oden & Massaro, 1978). The central question is how the models account for the influence of multiple sources of information on perceptual judgment. Although the two models can make somewhat similar predictions, the assumptions underlying the models are fundamentally different. The TRACE model is built around the concept of interactive activation, whereas the FLMP is structured in terms of the integration of independent sources of information. The models are tested against test results of an experiment involving the independent manipulation of bottom-up and top-down sources of information. Using a signal detection framework, sensitivity and bias measures of performance can be computed. The TRACE model predicts that top-down influences from the word level influence sensitivity at the phoneme level, whereas the FLMP does not. The empirical results of a study involving the influence of phonological context and segmental information on the perceptual recognition of a speech segment are best described without any assumed changes in sensitivity. To date, not only is a mechanism of interactive activation not necessary to describe speech perception, it is shown to be wrong when instantiated in the TRACE model.