A comparison of implicit memory tests in schizophrenic patients and normal controls

The objective of the current study was to compare the performance of schizophrenic patients and normal controls on implicit memory tests. Two neuropsychological tasks were administered to 29 patients and normal participant samples. The implicit tests were: Word fragment completion and Word production from semantic categories. The priming score was the variable of interest. Priming effects are obtained in normal subjects and schizophrenia patients, regardless of the implicit test used. However, a dissociation in priming between normal and patient groups was observed, depending on the test used. For word fragment test, priming was identical between the two groups. However, for word production, priming obtained in schizophrenics was lower than priming in normal controls. Results confirm a dissociation effect in implicit memory tests. These results could be explained in the context of the Roediger and Blaxton (1987) distinction between data-driven and conceptually-driven processing. This evidence suggests that a complete neuropsychological assessment of memory in schizophrenia should include different kinds of implicit memory tests (procedural, perceptual, and conceptual tasks).     

Perceived unpleasantness and facial reactions to auditory stimuli

This study examined whether facial electromyographic (EMG) reactions differentiate between identical tone stimuli which subjects perceive as differently unpleasant. Subjects were repeatedly exposed to a 1000 Hz 75 dB tone stimulus while their facial EMG from the corrugator and zygomatic muscle regions were measured. Skin conductance and heart rate responses were also measured. The subjects rated the unpleasantness of the stimulus and based on these ratings they were divided into two groups, High and Low in perceived unpleasantness. As predicted the facial EMG activity reflected the perceived unpleasantness. That is, the High group but not the Low group reacted with an increased corrugator response. The autonomic data, on the other hand, did not differ between groups. The results are consistent with the proposition that the facial muscles function as a readout system for emotional reactions and that facial muscle activity is intimately related to the experiential level of the emotional response system.     

Normal auditory negative priming in schizophrenic patients

Performance of 28 schizophrenic patients and 28 matched controls was compared in an auditory priming task. A large auditory negative priming effect was obtained for the patients as well as for the control group, and the size of the negative priming effect was approximately the same for both groups. Under the same conditions, positive or repetition priming for the patients was enhanced compared to that of the control group. The present findings from an auditory priming task are consistent with a growing body of evidence from the visual domain showing normal rather than reduced or eliminated negative priming in schizophrenic patients.     

Normal auditory negative priming in schizophrenic patients

Performance of 28 schizophrenic patients and 28 matched controls was compared in an auditory priming task. A large auditory negative priming effect was obtained for the patients as well as for the control group, and the size of the negative priming effect was approximately the same for both groups. Under the same conditions, positive or repetition priming for the patients was enhanced compared to that of the control group. The present findings from an auditory priming task are consistent with a growing body of evidence from the visual domain showing normal rather than reduced or eliminated negative priming in schizophrenic patients.     

Reaction times to auditory and visual stimulation in schizophrenic and normal subjects

An experiment carried out to determine the relation between auditory and visual reaction times suggested that when the general level of response is slow visual RTs are faster than auditory, and that the reverse is the case when the level of response is fast. Thus most normal subjects have an auditory RT faster than visual, and most schizophrenics the reverse. However, the difference between auditory and visual RTs does not appear to depend directly on schizophrenic pathology except in so far as this is a factor in the general slowness of reaction time.     

Self-focused attention in schizophrenic patients with and without auditory hallucinations and normal subjects: A comparative study

Self-focused attention has been implicated in a number of psychiatric disorders, but little research has examined this in schizophrenic subjects. In this study, a sample of schizophrenic patients experiencing auditory hallucinations, schizophrenic patients not experiencing auditory hallucinations and normal controls were asked to complete the private self-consciousness subscale of the Self Consciousness Scale. It was found that patients experiencing auditory hallucinations exhibited significantly higher levels of self-focus than those not experiencing hallucinations, although they did not differ from normal subjects. It was also shown that level of self-focus predicted whether or not subjects experienced hallucinations. These results, and their implications, are discussed with reference to the literature.     

Probability ratings in claustrophobic patients and normal controls

Forty-nine DSM-IV diagnosed claustrophobics and 49 sex- and age-matched community controls, without any current or past psychiatric disorder, were asked to estimate the probability that three types if events would occur if they were in the described situations. The events were claustrophobic, generally negative, and positive in nature. The results showed that claustrophobics significantly overestimated the probability of events they specifically feared, i.e. the claustrophobic events, while there was no difference between the groups regarding generally negative events and positive events. This finding remained when the higher scores for claustrophobics on the Claustrophobia scale and the Anxiety Sensitivity Index were covaried out. The conclusion that can be drawn is that claustrophobics' probability ratings are characterized by distortions that are specifically connected to anxiety-arousing events and not negative events in general. The hypothesis is proposed that this may be explained by an exaggerated use of simplified rules-of-thumb for probability estimations that build on availability in memory, simulation, and representativity.     

A token economy program for chronic schizophrenic patients

Abstract.— A token economy program was applied on a ward for 12 chronic schizophrenic patients. An ABABC-design, i.e. a group reversal design with a noncontingent reinforcement phase at the end, was used to evaluate the treatment. The patients' activity-level increased from baseline to the treatment phase. During the reversal period the activity-level decreased but it increased again when the token economy was reintroduced. The non-contingent reinforcement resulted in the predicted decrease for two of the six behaviors recorded. Five of the twelve patients were discharged from the ward during the 8-month program period and none of them had been readmitted at the end of the one year follow-up. Individual treatment programs for two of the patients concerning aggressive acts, deficient eye-contact and lip-biting are described.     

Lowering of an auditory threshold by a near threshold warning signal

Following previous experiments on the effect of suprathreshold “warning” signals in lowering the threshold for stimuli in another modality, we have used visual “warning” signals which are themselves within the threshold range. These near threshold “warnings” appear to act in exactly the same way as suprathreshold “warnings” provided they are seen. Very weak “warnings” have a reduced effect, probably because they are not always seen. The experiment is of interest in that it supports the theory that the effect is due to the “warning” signal reducing the subject's uncertainty about when the threshold stimulus will occur, and secondly because it indicates that under these conditions at least, the subject can attend effectively to two simultaneous near-threshold stimuli.     

A controlled evaluation of token economy procedures with chronic schizophrenic patients

Eighteen chronic schizophrenic patients were allocated to 3 matched groups, one group acting as an own-ward no-treatment control group. The two other groups moved to a token-economy ward, where the token group received contingent tokens, social reinforcement, and informational feedback as a consequence of appropriate behaviour, and where the control group received contingent social reinforcement and feedback with a matched amount of non-contingent tokens. After a 3 month baseline phase, this procedure was followed for a total of 15 months. A continuous assessment system was used with some weekly and monthly assessments, incorporating nursing checklists and ratings, psychiatric ratings, psychological tests, and time-sampling procedures, as well as continuous monitoring of the ward programme. The introduction of contingent tokens had an immediate positive effect in 3 areas of behaviour, but this advantage disappeared over the 15 months owing to the slower but sustained improvement in the control group. Significant improvement was limited to the areas of Social Withdrawal. Appearance and Routine. The patients who improved the most on any measure were those who were initially the most deteriorated. There were paradoxical changes in non-target behaviour, and in symptomatic behaviour. Suggestions and instructions to nurses may play a major part in influencing patient behaviour within and between experimental phases.