Dissociation theories of hypnosis.

Hypnotic responses have been attributed to 2 mechanisms that are characterized as dissociative. In E. R. Hilgard's (1986) neodissociation theory, responses are hypothesized to be due to a division of consciousness into 2 or more simultaneous streams, separated by an amnesic barrier that prevents access to suggestion-related executive functions, monitoring functions, or both. In K. S. Bowers's (1992) dissociated control theory, hypnotic inductions are hypothesized to weaken frontal control of behavioral schemas, thereby allowing direct activation of behavior by the hypnotist's suggestions. The authors review the empirical base, conceptual issues, and strengths and weaknesses of both theories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of Dissociation Throughout the Lifespan.

In the past 20 years, the study of dissociation has flourished partly because of the research on the links between traumatic events and dissociation. Epidemiological studies have shown that dissociative symptoms and disorders are not uncommon. The nonspecialist in this area needs a guide to the extensive literature on the evaluation of dissociation across the lifespan to choose the most appropriate form of evaluation. The authors provide summaries of various types of assessment for dissociation in infants, children, teens, and adults. The techniques they review include structured interviews, specialized questionnaires, and scales on more general instruments, along with their psychometric properties. A good evaluation of dissociation can guide diagnosis, help focus treatment, and provide a measure of treatment efficacy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of stimulus compounds by pigeons.

Used a matching-to-sample (MTS) procedure to investigate short-term memory for compound visual stimuli in 10 mixed-breed pigeons. In Exp I, a symbolic MTS procedure was used. Three Ss were trained to match element samples, and 3 were trained to match compound samples. Findings indicate that the compound-trained group did not learn to match the compound samples in terms of element matching rules but rather processed them as unitary events. In Exp II, Ss were trained to match either element or compound samples in a true MTS task. Both groups were able to match elements and compounds in the transfer test. Findings show that at least some compound stimuli were represented in a unitary, nonanalytic fashion until the S was exposed to the elements of the compound in isolation from the compound. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation in epilepsy and conversion nonepileptic seizures

PURPOSE: We examined the dimensionality of the item content of the Dissociative Experiences Scale (DES) in relation to the clinical diagnosis of conversion nonepileptic seizures (C-NES) versus complex partial epilepsy (CPE). METHODS: The DES was administered to a sex- and age-matched sample of 132 patients with C-NES and 169 with CPE and was factor analyzed with principal components analysis (PCA) with varimax rotation. RESULTS: The mean total DES score was 15.1 in the C-NES group and 12.7 in the CPE group (p = 0.079). The factors obtained by PCA differentiated the CPE and C-NES groups more strongly than did the total DES score. The factor accounting for the most variance, interpreted as "depersonalization-derealization," was significantly greater in C-NES than CPE (p = 0.005). An "absorption-imaginative involvement" factor, which included some of the clinical features of posttraumatic stress disorder was elevated only in subjects reporting histories of childhood abuse (p = 0.001) regardless of the diagnosis of CPE or C-NES. An "amnestic" factor appearing to represent memory problems related to neurologic impairment showed a trend toward elevation in CPE (p = 0.056) and may have confounded the CPE versus C-NES distinction using total DES scores. CONCLUSIONS: The DES has separate underlying dimensions that appear to relate distinctively to depersonalization and derealization, childhood trauma, and neurologic impairment. The heterogeneous item content of the DES is a potential confound that should be appreciated when this instrument is used to study dissociation in neuropsychiatric populations.     

Dissociation of fibronectin from gelatin-agarose by amino compounds

Soluble fibronectin of human plasma was specifically dissociated at neutral pH from gelatin-agarose by several cationic amino compounds, notably the polyamines spermine, spermidine and putrescine, the basic amino acid arginine, and amino sugars. The neutral and acidic amino acids and the N-acetylated derivatives of amino sugars tested were ineffective. Gel-filtration experiments demonstrated that [14C]spermidine bound to fibronectin but not to gelatin.     

Dissociation between location and shape in visual space.

There are often large perceptual distortions of shapes lying on the ground plane, even in well-lit environments. These distortions occur under conditions for which the perception of location is accurate. Four hypotheses are considered for reconciling these seemingly paradoxical results, after which 2 experiments are reported that lend further support to 1 of them-that perception of shape and perception of location are sometimes dissociable. The 2 experiments show that whereas perception of location does not depend on whether viewing is monocular or binocular (when other distance cues are abundant), perception of shape becomes more veridical when viewing is binocular. This means that perception of shape is not fully constrained by the perceived locations of the vertices that define the shape. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation as a predictor of psychopathology following burns injury

Forty-six burned adults were seen, on average 7 days after admission to hospital. Eighty per cent suffered from one or more dissociative symptoms during trauma and three or more dissociative phenomena were experienced by 19.5 per cent. Blunting or absence of emotion was the symptom most frequently reported. The number of dissociative phenomena during trauma was statistically significant and associated with extreme anxiety. The intensity of the dissociation-anxiety reaction during trauma was a predictor for psychopathology measured at the moment of discharge.     

Dissociation in the laboratory: a comparison of strategies

Several methods for inducing dissociation in the laboratory were examined in a sample of 78 undergraduate students. Participants scoring high or low on the Dissociative Experiences Scale participated in three dissociation challenge conditions: (a) dot-staring task, (b) administration of pulsed photic and audio stimulation and (c) stimulus deprivation. Participants recorded their dissociative experiences both before and after each of the three challenge conditions. Across conditions, high DES participants reported significantly more dissociative sensations than low DES participants, even after controlling for pre-challenge dissociation. Moreover, regardless of DES status, pulsed photo and audio stimulation produced the greatest level of dissociative symptoms. The findings suggest that the induction of dissociative symptoms in a nonclinical sample is easily accomplished in the laboratory and that those who report more dissociative symptoms in their day-to-day life exhibit more pronounced dissociative symptoms when undergoing dissociative challenge in the laboratory. Implications for the study and treatment of dissociative symptoms are discussed.     

Dissociation and schizophrenia. Schizophrenias--a dissociative nosopoietic construct?

The historical roots of the nosopoietic construct schizophrenia are traced: the nosographic construction by Kraepelin, an act of unification and split at the same time. The name schizophrenia reflects the tradition of the model of dissociation which is aetiologically connected with the idea of weakness of the synthetic power of the psyche: psychasthenia. In the establishment of the supposed nosological entity schizophrenia, the name-giving idea of dissociation was almost forgotten. Thus, nowadays Dissociative Disorders are classified in ICD and DSM separately from schizophrenic disorders, but it must be borne in mind that the schizophrenic disorders represent the most severe of disorders, hypothetically based on dissociation, namely, fragmentation of the ego.