A comparison between auditory hallucinations, interpretation of voices, and formal thought disorder in dissociative identity disorder and schizophrenia spectrum disorders.

OBJECTIVES: Dissociative identity disorder (DID) and schizophrenia-spectrum disorders (SSD) share some overlapping phenomenological features making accurate diagnosis more difficult. Childhood abuse and depersonalization have been associated with psychotic symptoms across psychological disorders but their relationship to psychotic phenomenology remains understudied. METHOD: The present study used quantitative measures to examine (1) similarities and differences in phenomenological voice hearing experiences, interpretations of voices, and thought disorder symptoms in individuals with DID (n = 44) or SSD (n = 45), and (2) whether depersonalization and childhood maltreatment influenced the initial pattern of findings. RESULTS: DID participants perceived their voices as being more internally located and generated, louder, and uncontrollable than SSD participants. Furthermore, the DID participants endorsed a greater frequency of thought disorder symptoms. Adding the covariates (sex, depersonalization, and child maltreatment) did not change the findings associated with location and origin of voices, and derailment, but there were now no differences in loudness or controllability. However, the schizophrenia sample reported more distress and metaphysical beliefs associated with voices, as well as more thought disorder incoherence and word substitution with the covariates controlled. CONCLUSION: While tentative, metaphysical interpretations of voices, incoherent thoughts and word substitution may reflect more psychotic processes.

Rat choice in rapidly changing concurrent schedules.

In two experiments, experimentally naïve rats were trained in concurrent variable-interval schedules in which the reinforcer ratios changed daily according to a pseudorandom binary sequence. In Experiment 1, relative response rates showed clear sensitivity to current-session reinforcer ratios, but not to previous sessions' reinforcer ratios. Within sessions, sensitivity to the current session's reinforcement rates increased steadily, and by session end, response ratios approached matching to the current-session reinforcer ratios. Across sessions, sensitivity to the current session's reinforcer ratio decreased with continued exposure to the pseudorandom binary sequence, contrary to expectations based on previous studies demonstrating learning sets. Using a second group of naïve rats, Experiment 2 replicated the main results from Experiment 1 and showed that although there were increases over sessions in both changeover rate and response rate during the changeover delay, neither could explain the accompanying reductions in sensitivity. We consider the role of reinforcement history, showing that our results can be simulated using two separate representations, one local and one nonlocal, but a more complex approach will be needed to bring together these results and other history effects such as learning sets and spontaneous recovery.

Testing the linearity and independence assumptions of the generalized matching law for reinforcer magnitude: a residual meta-analysis.

We conducted a residual meta-analysis to test the assumptions of the generalized matching law that effects of relative reinforcer magnitude on response allocation in concurrent schedules can be described by a power function and are independent from the effects of relative reinforcer rate. We identified five studies which varied magnitude ratios over at least four levels and six studies in which reinforcer rate and magnitude ratios were varied factorially. The generalized matching law provided a reasonably good description of the data, accounting for 77.1% and 90.1% of the variance in the two sets of studies. Results of polynomial regressions showed that there were no systematic patterns in pooled residuals as a function of predicted log response ratios for data sets in which relative magnitude was varied. For data sets in which relative rate and magnitude were varied factorially, there was a significant negative cubic pattern in the pooled residuals, suggesting that obtained response allocation was less extreme than predicted for conditions with extreme predicted values. However, subsequent analyses showed that this result was associated with results from conditions in one study in which the product of the rate and magnitude ratios was 63:1, and in which response allocation may have been attenuated by a ceiling effect. When data from these conditions were omitted, there were no significant components in the residuals. Although the number of available studies was small, results provide tentative support for the assumptions of the generalized matching law that effects of reinforcer magnitude ratios on choice can be described by a power function and are independent from reinforcer rate ratios.