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.