Stimulus generalization and the peak shift with movement stimuli

Stimulus generalization is suggested as an alternative method for examination of the "novelty" problem in motor learning. These experiments demonstrated that stimulus generalization occurs using simple movements as stimuli. The phenomenon of the "peak shift" in post-discrimination generalization gradients was also examined. The first experiment demonstrated that a peak shift occurred using linear movements as stimuli and that the magnitude of the peak shift increased as the difference between the training stimuli decreased. The second experiment showed similar results when the stimuli consisted of a range of movements rather than single movement length. The final experiment provided evidence that perception of movement length is influenced by the magnitude of an immediately preceding movement. The relevance of these studies to current motor-learning theory is discussed.     

Neuropsychological assessment of learning disabilities: a discriminant analysis

The neuropsychological test scores of 23 learning disabled children were compared with those of a matched population of normal children in the 9-1 to 13-1 age range. All children were administered the Wechsler Intelligence Scale for Children-Revised (WISC-R), a dichotic listening task involving both free and directed recall conditions, a handedness inventory, the Tactile Performance Test and the Category Test from the Halstead-Reitan Neuropsychological Test Battery. A multivariate analysis of variance resulted in a significant separation between groups (p less than .001) using these procedures. A stepwise discriminant function analysis revealed that both of the directed dichotic tasks contributed the most of all 13 measures to the significant group separation. In addition, other cognitive tasks found to discriminate normal from learning disabled children include general verbal processes, concept formation, and tactile memory. These findings suggest that the directed dichotic listening procedure and the WISC-R Verbal IQ measure are reasonably valuable clinical tools in the classification of learning disabilities.     

Effects of d-amphetamine on self-aggression and posturing in stumptail macaques

The behavioral effects of d-amphetamine sulfate were studied in adult male stumptail macaques living within a large heterogeneous group in an outdoor enclosure. Among five subjects that received a range of doses (.01 to .3 mg/kg), d-amphetamine increased self-aggressive behavior and abnormal posturing in subjects that exhibited these types of behavior prior to drug administration, but it had no effect in subjects not exhibiting those activities in the absence of the drug. For the former subjects, the dose-effect curves for self-aggression were of an inverted U-shape analogous to the effect of d-amphetamine on schedule-controlled behavior. Over the range of doses studied, the curve for abnormal posturing was monotonic. The data indicate that d-amphetamine can have effects on untrained behavior in individual animals in a quasinatural environment that are qualitatively and quantitatively similar to the behavioral effects observed in other laboratory environments, and that d-amphetamine does not evoke or increase a behavioral response in individual subjects that do not exhibit the response in the absence of the drug.     

Empirical sleep assessment in the home: A convenient,inexpensive approach

We have previously reported on a sleep assessment device (SAD) that addresses shortcomings inherent in self-report sleep data and polysomnography. The SAD produces a sleep record by tape recording subjects' verbal responses to auditory cues spaced at fixed intervals throughout the night. In prior studies, the SAD proved to be a reliable and valid assessment tool according to electroencephalographic comparisons. Herein, we report on the unassisted home use of the SAD by eight normal volunteers and four bedmates. Subjects and bedmates completed sleep questionnaires for 12 nights and subjects also employed the SAD the last 6 nights. Comparisons of subjects and bedmates self-report sleep data before and during SAD use indicated that the SAD did not disrupt sleep. Subjects were able to self-administer successfully the SAD in their homes. SAD data closely matched subjects' self-report data. The present study found the SAD to be an accurate, unobtrusive, and easily utilized empirical measure of sleep in the natural environment. In so doing, it extends the demonstrated reliability and validity of the SAD from the sleep laboratory to the home with normal sleepers.     

Accommodation fatigue and dark focus: The effects of accommodation-free visual work as assessed by two psychophysical methods

Past studies of accommodation fatigue have yielded inconsistent results, partly because they have not used direct measures of accommodation, and partly because they may have been based on a misleading conception of the nature of accommodation. The dual-innervation theory of accommodation suggests that the resting position of accommodation may be neuromuscular rather than just muscular, and that it lies not at optical infinity, as assumed by older conceptions, but at some intermediate position (dark focus). Among the predictions that may be deduced from this theory is that long-term visual work not requiring active accommodation will not induce fatigue. The present study involved continuous measurements of dark focus for 10 young adults over a 3-h period, using the laser optometer with two psychophysical procedures Ibracketing and staircase. Consistent with the prediction, no changes in dark focus were found, in spite of the demanding visual task. Furthermore, it was found that both psychophysical methods yielded essentially identical results. The practical and theoretical implications of these results are discussed, and recommendations are given regarding situations in which each of the psychophysical methods is likely to be most useful.     

Glutamate as a transmitter in the CNS and its presumed significance in the pathogenesis of cerebral seizure forms--recent aspects

Glutamate is believed to be quantitatively the most outstanding of the excitatory transmitters in the CNS. Certain conformationally related analogues, e. g. kainate, N-methyl-D-aspartate, ibotenate, and homocysteate, act as glutamate agonists. The local or systemic administration of these "excitotoxic" compounds induces epileptiform activity pointing out new and deeper insights into the epileptic process. Additionally, the glutamate transmitter hypothesis is expected to give a chance of a causal comprehension for choreatic processes as well as for the mode of action of anticonvulsant and antispastic agents.     

The structural theory and the representational world: developmental and biological considerations

Although the intriguing question of whether the division into two viewpoints within the structural theory is a theoretical convenience or whether it mirrors fundamental psychobiological truths is not capable of full resolution at the moment, fortunately that resolution is not required for our usual clinical purposes. I believe that analytic work presents us with data readily conceptualized now from one, now from the other, viewpoint, so that analytic understanding benefits from the analyst's shifting his frame of reference from moment to moment in listening and associating to the patient's material. I believe that in every event within the analytic situation or in a person's life, our understanding is deepened and made more complete by approaching the phenomena from both vantage points, bearing in mind that the same ego we conceptualize as testing, assessing, and evaluating emergent drives is also assessing the congruence or discrepancy between the wished-for and perceived states of the representational world. These processes are occurring both in the analysand and in the analyst who is attempting to resonate with and understand the intrapsychic functioning of his patient. They constitute two observational vantage points within the structural theory, organizations of motives (Friedman, 1980) either of which may offer the most immediate access to understanding a particular segment of clinical material. I believe our understanding is most often deepened, however, by subsequent scrutiny in the light of the other model. I have tried here to supplement my previous exposition of a representational world point of view (J.G. Jacobson, 1983) by providing some of its developmental, ethological, and psychophysiological landmarks and underpinnings.