The analysis of the EEG

The quantitative analysis of the electroencephalogram (EEG) relies heavily on methods of time series analysis. A quantitative approach seems indispensable for research (be it clinical or basic neurophysical research), but it can also be a useful information for purely clinical purposes. Apart from the ongoing spontaneous EEG, evoked potentials (EPs) also play an important role. They can be elicited by simple sensory stimuli or more complex stimuli. Their analysis requires methods which are different from those for the spontaneous EEG. Those methods operate usually in the time domain and offer many challenging problems to statisticians. Methods for analysing the spontaneous EEG usually work in the frequency domain in terms of spectra and coherences. Biomedical engineers who take care of the equipment are usually also trained in time series analysis. Thus, they have contributed much more to methodological progress for analysing EEGs and EPs, compared with statisticians. However, the availability of a sample of subjects, and the associated problems in modelling followed by an inferential analysis could make a larger influence from the statistical side quite profitable. This paper tries to give an overview of a fascinating area. In doing so we treat more extensively problems with some statistical appeal. This leads inevitably to some overlap with our own work.     

Recidivism rates among child molesters and rapists: a methodological analysis

We address the high variability in sex offender recidivism rates by examining several of the critical methodological differences that underlie this variability. We used a dataset on 251 sex offenders (136 rapists and 115 child molesters) who were discharged over a 25-year period to examine changes in recidivism as a function of changes in dispositional definition of reoffense (e.g., arrest or conviction), changes in the domain of criminal offenses that are considered, and changes in the length of exposure time. The data indicate that: (a) both rapists and child molesters remain at risk to reoffend long after their discharge, in some cases 15-20 years after discharge; (b) there was a marked underestimation of recidivism when calculating a simple proportion (%) consisting of those who were known to have reoffended during the follow-up period, and (c) there was a marked underestimation of recidivism when the criterion was based on conviction or imprisonment. Forensic, clinical and policy implications of this high variability are discussed.     

Aggression and the EEG: A quantitative analysis.

80 male offenders (mean age 33.93 yrs) at a psychiatric security hospital completed scales of aggression and hostility and were rated on previous history of assaulative behavior. Two psychiatrists agreed that 45 Ss had personality disorders and 35 were psychotic. Low frequency analysis was employed to obtain measures of EEG abundance at rest, during repetitive auditory stimulation, and during the cold pressor test. Neither within the sample as a whole nor within personality disorders alone was any relation found between resting abundance and aggression. More aggressive Ss tended to have a higher dominant frequency at rest, less increase in theta during monotonous stimulation, and greater alpha reactivity to cold pressor stimulation. Results are not in accord with the view that a high prevalence of theta activity characterizes aggressive offenders. The evidence of greater cortical excitability in aggressive patients suggests that persistent aggression is associated with a dominance of the ergotropic system. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpersonal dynamics in a simulated prison: A methodological analysis.

Analyzes the Stanford Prison experiment of P. G. Zimbardo et al (1973) and questions, on methodological grounds, various of their inferences. Empirical evidence is presented to elucidate and buttress these criticisms, and an alternative interpretation of the outcome of the Stanford experiment is proposed. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects on recall of hypnotic induction, motivational suggestions, and suggested regression: A methodological and experimental analysis.

90 Ss were assessed for recall of syllables (learned 2 mo. previously) under 1 of 9 experimental conditions in a 3 X 3 factorial design. The 3 levels of the 1st independent variable were: hypnotic induction, eyes closed; no induction, eyes closed; and no induction, eyes open. The 3 levels of the 2nd independent variable were: recall without suggestions; recall with motivational suggestions; and recall with suggestions to regress to the time of original learning. Recall was not affected by the independent variables or their interaction. A comparable number of Ss in each of the 9 experimental groups testified postexperimentally that, during the experiment, they had imagined, felt, and believed they were back in the original learning situation. (30 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

P50 suppression among schizophrenia and normal comparison subjects: a methodological analysis

The present report investigated the relationship between P50 suppression and habituation among 20 schizophrenia and 20 normal comparison subjects. Subjects were presented with clicks delivered over headphones in a S1-S2 paradigm (clicks were separated by 500 msec; average intertrial interval was 8 sec). There were 60 total trials; the data were analyzed separately for the first and second 30 trials. The groups did not differ either on the number of usable trials or on the morphology of their P50 responses. Consistent with previous reports, schizophrenia patients demonstrated deficient P50 suppression. The overall suppression effect was not due to a group difference on S1 P50 amplitudes, but was associated with schizophrenia patients having smaller S1-S2 P50 amplitude difference scores than normal comparison subjects. Furthermore, the suppression effect appears to be more pronounced during the first than during the second block of trials. Thus, it may be important to evaluate changes in P50 responses over time among schizophrenia and normal comparison subjects.     

The methodological aspects of experimental modelling and of assessing the hereditary sequelae of the irradiation of one and both parents

The paper summarises some methodological approaches which may be used in experimental modelling and study of hereditary radiation effects in mammals. These approaches are aimed to the elucidation of the possible specific character (aggravation) of radiation damage in the offspring determined by the participation of two exposed parents in conception. The main attention is drawn to the dependence of hereditary radiation effects yield on the stages of the cell cycle of the parent germ cells at the moment of exposure and to criteria of evaluation of radiation damage in the offspring during the ontogenetic development.     

The hemispheric relationships of the human brain during the recovery of consciousness after a long-term coma: an EEG analysis

Analysis of the intra- and interhemispheric EEG coherence in the dynamics of coma regress and its comparison with the clinical stages of postcomatose recovery period revealed both specific interhemispheric rearrangements of the structure of intercentral functional relations, which developed in parallel with the recovery at first of the visual, and then speech functions, and the adaptive-compensatory changes in activity of the regulatory systems, which provide the recovery of mental functions. It is emphasized that the interhemispheric EEG coherence asymmetry, its character and dynamics are significant for formation of neurophysiological mechanisms of consciousness and the course of compensatory processes under the extreme conditions.     

The Hawthorne effect: A reconsideration of the methodological artifact.

Reviews the literature on the Hawthorne effect (HE) which originated out of the studies at the Hawthorne Works of the Western Electric Company. This effect is generally defined as the problem in field experiments that Ss' knowledge that they are in an experiment modifies their behavior from what it would have been without the knowledge. An examination of the Hawthorne studies conducted 50 yrs ago does not reveal this "effect" probably because there were so many uncontrolled variables. HE is inconsistently described in contemporary psychology textbooks, and there is lack of agreement on how the effect is mediated. Controls for the HE in current field research (mostly in education) took several forms, each designed for different purposes. In 13 studies designed to produce HEs, only 4 using adult Ss were successful. It is suggested that most persons in any clearly identified situation define the context for their behavior and respond accordingly; the necessity to ascertain Ss' view of the experiment requires different procedures than those typically used to control for HEs in the past. It is concluded that better articulation of how to adapt postexperimental questioning procedures to a diversity of experimental settings is needed. (68 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of facial response in the experience of emotion: More methodological problems and a meta-analysis.

A recent review of the facial feedback literature by Laird (1984) suggested that the effect of facial movement on self-reported mood is large and consistent. In this article, two issues are discussed that suggest that these conclusions are unwarranted. First, methodological problems concerning the facial expressions used to represent valid analogs of emotion and the arousal value of the emotion-eliciting stimuli seriously bring into question the adequacy of the studies to test facial feedback as implied by Izard (1971, 1977) or Tomkins (1962, 1963). Second, even if one accepts the studies designed to represent tests of the effect of facial behavior on self-reported mood, Laird's (1984) box-score approach cannot provide an estimate of the magnitude of the effect. Using meta-analytic techniques (Hunter, Schmidt, & Jackson, 1983; Rosenthal, 1984), I show that the effect size of facial behavior on self-reported mood is actually only of small to moderate value and is most likely an inflated estimate. I conclude, on the basis of the evidence presently available, that the effect of facial feedback on emotional experience is less than convincing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Regional MRI measurements of the corpus callosum: a methodological and developmental study

A technique for quantifying the midsagittal size and shape of the corpus callosum (CC) from magnetic resonance brain scans is presented. The technique utilizes the distances to the ventral and dorsal boundaries of small sectors of the CC from a reference point to compute the size and shape parameters of the CC and its subdivisions. Intrarater and interrater interclass correlation coefficients for the area measurements ranged from 0.88 to 0.99. Correlations between these automated measures and those obtained by pixel counting were equally high. The corpus callosa of 104 (57 male and 47 female) right-handed healthy children and adolescents, ages 4-18, were examined in relation to age and sex. Corpus callosum growth was most striking for the splenium and isthmus with some changes in the midbody regions. The area and perimeter of these regions increased, shapes became more compact, and the boundaries became more regular with age. The length and curvature at the anterior and posterior regions of the CC increased more rapidly in males than in females. These significant and consistent results indicate that the method is reliable and sensitive to developmental changes of the CC.     

The effects of threat in bargaining: Critical and experimental analysis.

A 1st experiment replicated the main result of the Deutsch and Krauss experiment which showed that the presence of barriers in the bargaining situation led to poorer outcomes for the players. It also indicated, however, that the main results obtained by Deutsch and Krauss and the similar ones found in the present experiment are probably due to the spurious effect of the length of the longer pathway and the lack of comparability between conditions. In a 2nd experiment, the introduction of electric shock—whether given no interpretation, interpreted as a means of coercing the other to yield, or interpreted as a means of threatening future unpleasantness—did not significantly change the outcomes for the bargainers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of the work environment on cardiovascular health: a historical, conceptual, and methodological perspective

The framework of psychosocial epidemiology is used to examine research developments that characterize the accumulation of knowledge regarding the role of the work environment in cardiovascular health and disease. The discussion of current programs of research focuses on the work of T. Theorell and R. Karasek (1996) and J. Siegrist (1996) as exemplars of European and American studies that have contributed the most to the understanding of occupational cardiovascular health. It is argued that researchers need to maintain and nurture relatively broad conceptual models of etiology because cardiovascular disease involves multiple biomedical risk factors and because specific aspects of the work environment are embedded in a large, complex matrix of other psychosocial influences. At the same time, investigators need to push ahead with focused research strategies to clarify the precise nature of the work environmental risk factors that emerge in the broad, somewhat imprecise epidemiologic study designs.     

Nutrient regulation of gene expression: a methodological strategy

Nutrients should be viewed as the earliest of the hormone signals which allowed an organism to respond to changes in its nutrient environment. Defining nutrient function at the nuclear level will permit us to understand how our dietary environment is related to the development of nutritionally related pathophysiologies such as diabetes, heart disease, and cancer. Moreover, through the application of molecular techniques, we will begin to understand how specific nutrients govern the developmental pattern of specific organs such as the kidney. In this review, the fatty acid synthase gene is employed as a model to demonstrate how one sequentially approaches questions pertaining to the regulation of gene expression by a nutrient, and the article presents a nuclear explanation for how dietary polyunsaturated fats decrease blood triglycerides. More importantly, studies of this nature provide a basis for screening genetically susceptible populations and information that will allow the nutritionists of the 21st century to customize a diet for patients at risk.