Increased frequency of involuntary semantic memories or mind-pops in schizophrenia: a diary study.

INTRODUCTION: Hallucinations constitute a prominent symptom of schizophrenia and may take a variety of forms (verbal, visual, musical, or environmental noises). Interesting similarities exist between hallucinations and so-called mind-pops which refer to isolated fragments of one's semantic knowledge (e.g., a word/sentence, visual image, or a song/melody) that come to mind unexpectedly, often without any obvious triggers, and are difficult to control. The aim of the present study was to evaluate whether mind-pops may constitute the raw cognitive material from which hallucinations are constructed by studying the nature and frequency of mind-pops in the everyday life of people with schizophrenia and non-clinical controls. METHODS: Eleven participants with schizophrenia and 14 non-clinical controls kept a diary of their mind-pops for seven days and completed a brief questionnaire every time they had a mind-pop. RESULTS: Schizophrenia participants reported significantly more verbal and image mind-pops than controls and their content was negative more often than in controls. No group differences were obtained in terms of reported triggers or ongoing activities. Data from both groups also supported the priming hypothesis by showing that stimuli encountered in one's environment or thoughts could later re-appear in the form of a mind-pop. CONCLUSIONS: The findings have implications for models of schizophrenia that emphasise the role of intrusive thoughts and memories in the aetiology and development of key psychotic symptoms.

From mind-pops to hallucinations? A study of involuntary semantic memories in schizophrenia.

Involuntary semantic memories or mind-pops consist of isolated fragments of one's semantic knowledge (e.g., a word or a sentence, proper name, image or a melody) that come to mind unexpectedly, without any deliberate attempt to recall them. They can be experienced as alien and uncontrollable, and may share some phenomenological similarities with hallucinations. The aim of the present study was to investigate the nature and frequency of mind-pops in people with schizophrenia (N=37), as well as clinically depressed (N=31) and non-clinical controls (N=31). Results showed that schizophrenia patients reported experiencing mind-pops more frequently than both depressed and non-clinical controls. Schizophrenia patients also reported a wider range of different types of mind-pops than non-clinical controls. The depressed group did not differ from non-clinical controls in the frequency and range of mind-pops, indicating that mind-pops are not characteristic of clinical populations in general, but may be particularly prevalent in patients with schizophrenia. The possible implications of this finding to current models of auditory verbal hallucinations are discussed and the need for future research in this area is emphasized.