Reality discrimination, reality monitoring and disposition towards hallucination

Abstract

This investigation tested the hypotheses that individuals disposed towards hallucination are deficient in the meta-cognitive skills of reality discrimination and reality monitoring, and that there is a strong correlation between the measures of these skills. Normal subjects scoring high or low on a scale measuring predisposition towards hallucination were tested on an auditory signal detection task. High scorers on the scale were found to differ from low scorers on a measure of perceptual bias but not on a measure of sensitivity. The same groups of subjects were tested on a reality monitoring measure in which they were required to monitor two different types of word: words they were required to listen to, and words they were required to listen to on some trials and imagine on others. On a surprise frequency test it was found that high scorers did not differ from low scorers on their ability to accurately count the memories of words they had heard. It was also found that both high scorers and low scorers overestimated the number of times they had heard words when they had also been required to imagine these words on tests; however, high scorers made this error to a significantly greater extent. A strong correlation was found between reality discrimination and reality monitoring measures for high scorers, but no correlation was found for low scorers.

Do Positive Schizotypal Symptoms Predict False Perceptual Experiences in Nonclinical Populations?

“…When the task required a yes (target presence) or no (target absence) response, high schizotypy scorers demonstrated a positive response bias, although their accuracy remained intact. These findings replicate and extend past evidence, in the visual modality, that hallucinations, as well as psychometrically defined proneness to hallucinations, are linked to a bias toward believing that an auditory stimulus is present in the absence of such a stimulus (Bentall and Slade, 1985;Rankin and O'Carroll, 1995). Furthermore, when the task required a detailed description of the target (strict condition), positive schizotypal symptoms predicted false perceptions of words.…”

“…The same effect has been replicated in undergraduate students who score highly on measures of predisposition to hallucinations (Bentall and Slade, 1985;Rankin and O'Carroll, 1995). However, it remains unclear whether or not these participants actually had false perceptual experiences.…”

“…The main reason for studying such a bias as a function of symptoms of schizotypy in undergraduate students rather than schizophrenia patients was the utility of this approach in avoiding possible confounds (medication, hospitalization, and so forth) often inherent in research with clinical participants. Our main hypothesis was that positive schizotypal symptoms would predict false alarms, but not accuracy, replicating in the visual modality past evidence (Bentall and Slade, 1985;Cahill et al, 1996;Rankin and O'Carroll, 1995). In addition, we tested whether such bias would survive a strict response criterion (i.e., whether positive schizotypal symptoms would predict false perceptions of words).…”

Impaired performance in a working memory binding task in patients with schizophrenia

“…For example, patients with schizophrenia exhibit impairments of memory for temporal information (Schwartz et al, 1991;Rizzo et al, 1996), frequency of occurrence of events (Gras-Vincendon et al, 1994), and reality monitoring (i.e. determining if information was self-generated or provided by the experimenter) (Bentall et al, 1991;Rankin and O'Carroll, 1995). Such findings raise the possibility that episodic memory deficits in patients with schizophrenia may be related to a failure of binding features together to create more complex representations (Rizzo et al, 1996;Danion et al, 1999).…”

Recent developments in the management of delusional disorders

“…Rankin 1995;Sharp 1997;Garety 1999;Bentall 2001). Although these could be criticised for missing the point that associated affect and psychotic experiences can have a profound effect in maintaining an individual's delusional system, they were invaluable in providing an evidence base for exploring and challenging a patient's abnormal beliefs.…”