Better discrimination of small changes in commonly encountered than in less commonly encountered auditory stimuli

Results from 3 auditory tasks revealed that small changes made in stimuli commonly encountered in everyday life are more easily discriminated than are the same changes made in stimuli not as commonly encountered. The tasks required discrimination of a frequency difference in 1 tone of 6-tone chords or nonchords, discrimination of a duration difference in 1 note of common tunes or nontunes, and discrimination of the deletion of a band of frequencies from speech sounds played forward or backward. Different crews of college-aged listeners served in the different tasks. If future research shows this difference in discriminability to be a general property of commonly encountered stimuli--attributable to a difference in the way they are processed in the nervous system--then discrimination tests of this sort could become useful for assessing whether stimuli have made the transition from one form of processing to the other.     

A developmental grammar for syllable structure in the production of child language.

The order of acquisition of Dutch syllable types by first language learners is analyzed as following from an initial ranking and subsequent rerankings of constraints in an optimality theoretic grammar. Initially, structural constraints are all ranked above faithfulness constraints, leading to core syllable (CV) productions only. Subsequently, faithfulness gradually rises to the highest position in the ranking, allowing more and more marked syllable types to appear in production. Local conjunctions of Structural constraints allow for a more detailed analysis.     

Frequency of perseveration in normal subjects

Although perseveration is a recognized sign of disturbed brain function, it also occurs in normal individuals. Determination of the frequency of perseveration in normal subjects would enable clinicians to use perseveration as a marker of possible pathology. The purpose of this study was to document the extent of perseveration in normal young and older subjects. Thirty young normal individuals between the ages of 20 and 35 years and 30 older normal individuals between the ages of 60 and 75 years were given four tasks on which perseveration has been reported in brain-damaged individuals. Four percent of all responses were perseverative. No age or gender effects on frequency were observed. Of the four neuropsychological tasks, the Modified Wisconsin Card Sorting Test elicited the greatest number of perseverations.     

The medico-legal status of young sex offenders: forensic psychiatric evaluations in Sweden 1988-1995.

Young sex offenders (YSOs) attract significant public and professional concern. YSOs might be perceived as more psychologically deviant or dangerous than other offenders. This study focused on how often YSOs subjected to forensic psychiatric investigation (FPI) were declared medico-legally insane as compared to young non-sex offenders and adult sex offenders. Logistic regression models were applied to data from all major FPIs performed in Sweden between 1988 and 1995 (N=4354) to explore factors affecting the likelihood of receiving a medico-legal insanity declaration. When we adjusted for the statistical effects of age, sex offender status, and psychopathology, YSOs (n=47) were three to four times more likely to be declared insane in the medico-legal sense. The results indicate that YSOs in Sweden constitute a medico-legally distinct subgroup of forensic psychiatric examinees.     

A longitudinal study of negative affect and self-perceived competence in young adolescents.

In a 4-wave, 2-year longitudinal design, the authors obtained measures of negative affect (NA) and self-perceived competence from 220 boys and 216 girls who were 7th graders at the beginning of this study. NA was operationalized as the common dimension underlying self-reports of depressive symptoms, anxiety symptoms, and negative emotions. Self-perceived competence consisted of 2 higher order constructs: a well-behaved/good-student factor and an attractive/athletic/popular factor. Structural equation modeling revealed very high stability estimates for all constructs. Nevertheless, self-perceived competence in the attractive/athletic/popular domain predicted changes in NA. Conversely, NA predicted changes in self-perceived competence in the well-behaved/good-student domain. The primacy of NA versus self-cognitions depends, in part, on the type of self-cognitions being examined.     

Construct validity of the Sivik Psychosomaticism Test and test of operational style: correlations with Karolinska Scheme of Personality.

To evaluate the construct validity (convergent and divergent) of Sivik Psycho Somaticism test (SPS) and test of Operationality (OPER), Pearson correlation coefficients between SPS scales and subscales and Karolinska Scheme of Personality (KSP) were calculated. Seventy-eight healthy individuals and 196 psychosomatic patients completed the SPS and OPER tests and KSP. The results show that the SPS and OPER subscales are significantly correlated to most KSP subscales. The correlations were higher for the psychosomatic group than for the normal population. The results confirm the validity of the SPS and OPER constructs.     

Simulating consciousness in a bilateral neural network: "nuclear" and "fringe" awareness

A technique for the bilateral activation of neural nets that leads to a functional asymmetry of two simulated "cerebral hemispheres" is described. The simulation is designed to perform object recognition, while exhibiting characteristics typical of human consciousness-specifically, the unitary nature of conscious attention, together with a dual awareness corresponding to the "nucleus" and "fringe" described by William James (1890). Sensory neural nets self-organize on the basis of five sensory features. The system is then taught arbitrary symbolic labels for a small number of similar stimuli. Finally, the trained network is exposed to nonverbal stimuli for object recognition, leading to Gaussian activation of the "sensory" maps-with a peak at the location most closely related to the features of the external stimulus. "Verbal" maps are activated most strongly at the labeled location that lies closest to the peak on homologous sensory maps. On the verbal maps activation is characterized by both excitatory and inhibitory Gaussians (a Mexican hat), the parameters of which are determined by the relative locations of the verbal labels. Mutual homotopic inhibition across the "corpus callosum" then produces functional cerebral asymmetries, i.e., complementary activation of homologous "association" and "frontal" maps within a common focus of attention-a nucleus in the left hemisphere and a fringe in the right hemisphere. An object is recognized as corresponding to a known label when the total activation of both hemispheres (nucleus plus fringe) is strongest for that label. The functional dualities of the cerebral hemispheres are discussed in light of the nucleus/fringe asymmetry.