Hallucinations in schizophrenia, sensory impairment, and brain disease: a unifying model

Based on recent insight into the thalamocortical system and its role in perception and conscious experience, a unified pathophysiological framework for hallucinations in neurological and psychiatric conditions is proposed, which integrates previously unrelated neurobiological and psychological findings. Gamma-frequency rhythms of discharge activity from thalamic and cortical neurons are facilitated by cholinergic arousal and resonate in networks of thalamocortical circuits, thereby transiently forming assemblies of coherent gamma oscillations under constraints of afferent sensory input and prefrontal attentional mechanisms. If perception is based on synchronisation of intrinsic gamma activity in the thalamocortical system, then sensory input to specific thalamic nuclei may merely play a constraining role. Hallucinations can be regarded as underconstrained perceptions that arise when the impact of sensory input on activation of thalamocortical circuits and synchronisation of thalamocortical gamma activity is reduced. In conditions that are accompanied by hallucinations, factors such as cortical hyperexcitability, cortical attentional mechanisms, hyperarousal, increased noise in specific thalamic nuclei, and random sensory input to specific thalamic nuclei may, to a varying degree, contribute to underconstrained activation of thalamocortical circuits. The reticular thalamic nucleus plays an important role in suppressing random activity of relay cells in specific thalamic nuclei, and its dysfunction may be implicated in the biological vulnerability to hallucinations in schizophrenia. Combined with general activation during cholinergic arousal, this leads to excessive disinhibition in specific thalamic nuclei, which may allow cortical attentional mechanisms to recruit thalamic relay cells into resonant assemblies of gamma oscillations, regardless of their actual sensory input, thereby producing an underconstrained perceptual experience.     

Noncontingent reinforcement, alternative reinforcement, and the matching law: a laboratory demonstration

Basic researchers, but not most applied researchers, have assumed that the behavior-decelerating effects of noncontingent reinforcement result at least partly from adventitious reinforcement of competing behaviors. The literature contains only sketchy evidence of these effects because few noncontingent reinforcement studies measure alternative behaviors. A laboratory model is presented in which concurrent schedules of contingent reinforcement were used to establish a "target" and an "alternative" behavior. Imposing noncontingent reinforcement decreased target behavior rates and increased alternative behavior rates, outcomes that were well described by the standard quantitative account of alternative reinforcement, the generalized matching law. These results suggest that adventitious reinforcement of alternative behaviors can occur during noncontingent reinforcement interventions, although the range of conditions under which this occurs remains to be determined in future studies. As an adjunct to applied studies, laboratory models permit easy measurement of alternative behaviors and parametric manipulations needed to answer many research questions.     

Amplitude scaling in a bimanual circle-drawing task: pattern switching and end-effector variability

The authors manipulated movement amplitude in a bimanual circle-tracing task performed by 11 participants. With pacing frequency fixed, the systematic increase and decrease of circle diameter within a trial induced phase transitions from the asymmetric (33% of trials) to the symmetric bimanual circle-tracing pattern; the transitions resulted from a loss of stability in the asymmetric pattern. Tracing frequency varied inversely with circle diameter so that end-effector variability was minimized in a set of self-paced trials in which the circle diameter in a trial was fixed. In the amplitude-scaling trials, end-effector variability varied directly with circle diameter, a consistent speed-accuracy tradeoff. The results support the conclusion that movement amplitude is a nonspecific control parameter. The findings are discussed with reference to several factors, e.g., tactile feedback, the recruitment and suppression of biomechanical degrees of freedom, and the role those factors may play in stabilizing bimanual coordination patterns     

Bullying and victimization: prevalence and relationship to gender, grade level, ethnicity, self-esteem, and depression

This study investigated the prevalence of bullying and victimization among students in grades 7 and 8. It also explored the relationship of bullying and victimization to gender, grade level, ethnicity, self-esteem, and depression. Three survey instruments were used to obtain data from a convenience sample of 454 public school students. Twenty-four percent reported bullying involvement. Chi-square tests indicated significantly more male than female bullying involvement, seventh graders reported more involvement than did eighth graders, and there were no statistically significant differences in involvement based on ethnicity. Both bullies and victims manifested higher levels of depression than did students who were neither bullies nor victims. There were no significant differences between groups in terms of self-esteem.     

Assessing the factorial invariance of Harter's self-concept measures: comparing preadolescents with and without spina bifida using child,parent, and teacher report

The purpose of this study was to determine whether the structure of children's self-concept, as rated by children themselves on the Self-Perception Profile for Children (SPPC; Harter, 1985), and the structure of children's competence, as rated by their parents on the Rating Scale of Child's Actual Behavior (PRS) and teachers on the Rating Scale of Child's Actual Behavior (TRS; Harter, 1985), are similar across samples of children with and without spina bifida (children were 8 and 9 years of age; n = 68 in each sample). Using confirmatory factor analyses, results revealed that a multidimensional model for the SPPC and the TRS fit the data well for both samples. On the other hand, the model for both mothers' and fathers' PRS ratings did not fit the data for the spina bifida sample. Further tests of factorial invariance conducted on the SPPC and TRS revealed that the spina bifida and able-bodied samples tended to have the same pattern and magnitude of factor loadings for both instruments. There was some invariance, however, in the amount of unique error variance accounted for across samples. These results bolster our confidence in using the SPPC and TRS to compare children with and without spina bifida.     

Four studies extending the utility of the Schwartz Outcome Scale (SOS-10)

The Schwartz Outcome Scale (SOS-10; Blais et al., 1999) is a brief, cost free, and easy to administer assessment device designed to measure a broad domain of psychological health. The 4 studies using the SOS-10 reported here extend the initial reliability and validity studies beyond psychiatric patients in a hospital setting to examine (a) test-retest reliability in a college student population, (b) concurrent validity with college students using an indirect technique assessing maladjustment, (c) concurrent validity with college counseling center clients using a self-report measure of client distress, and (d) sensitivity to treatment changes with outpatient clients. These studies lend further support for using the SOS-10 as a measure of psychological well-being and as an outcome measure in varied settings.     

Feeling textures through a probe: effects of probe and surface geometry and exploratory factors

Vibratory roughness perception occurs when people feel a surface with a rigid probe. Accordingly, perceived roughness should reflect probe and surface geometry, exploratory speed, and force. Experiments 1 and 2 compared magnitude estimation of roughness with the bare finger and two types of probes, one designed to eliminate force moments, under the subject's active control. Experiments 3 and 4 varied speed under passive control. Log magnitude was consistently a quadratic function of log spacing between elements in the surface. The location of the function's peak was related to the drop point--that is, the spacing at which the probe can just drop between elements--which is affected by probe tip diameter, element height, and speed. Other parameters of the quadratic were affected by probe type and speed.     

Evaluation of bizarre-idiosyncratic thinking scale as a measure of thought disorder in children and adolescents with severe psychiatric disorders

To investigate the prevalence of thought disorder and the possible appropriateness of the Bizarre-Idiosyncratic Thinking Scale for children and adolescents with severe psychiatric disorders, 96 child and adolescent inpatients and day hospital patients, ages 6 to 18 years, at a state psychiatric hospital were rated by review of retrospective records using Marengo and Harrow's 1986 Evaluation of Bizarre-Idiosyncratic Thinking Scale for the presence of thought disorder in the Thematic Apperception Test and Rorschach Inkblot Test responses. Although the Evaluation of Bizarre-Idiosyncratic Thinking Scale had not been previously used with children and adolescents, the analysis suggested possible indications of thought disorder in several diagnostic groups. No significant differences were found on the Rorschach between patients with Schizophrenia and Psychosis, Not Otherwise Specified and those with Attention Deficit Hyperactivity Disorder, Major Depression, and Conduct Disorder. On the basis of the Thinking Scale ratings, the Thematic Apperception Test responses showed significantly higher ratings of thought disorder for patients with Schizophrenia and Psychosis, Not Otherwise Specified. There was no general relation between thought disorder and age or IQ, but schizophrenic patients, aged 13 and older, had more thought disorder than schizophrenic patients who were younger than 13.     

It's not my fault: when and why attributions to prejudice protect self-esteem

This study tested the hypothesis that awareness of the possibility of being a target of discrimination can provide individuals with a means of self-esteem protection when they are faced with negative outcomes. Men and women contemplated being rejected from a course due to sexism, personal deservingness, or an exclusively external cause. Regardless of gender, participants in the sexism condition blamed themselves less, attributed the rejection less to internal causes, and anticipated feeling less depressed than those in the personal deservingness condition. Furthermore, the more participants discounted the rejection--blamed it more on discrimination than themselves--the less depressed emotions they anticipated feeling. Discounting did not buffer participants from feeling hostility or anxiety. These findings advance our understanding of when and why attributions to prejudice protect emotional well-being.