The following article discusses the phenomenon of auditory hallucinations in those who do not suffer from schizophrenia. Research has shown the occurrence of auditory hallucinations in the general population to such an extent that they cannot be said to be pathognomonic of psychiatric illness. In addition, it has long been known that certain hallucinatory experiences occur in health, such as hypnagogic and hypnopompic hallucinations. However, there are fundamental differences in the characteristics of these experiences. In the psychiatric population, these tend to be frequent, intrusive, and distressing. In contrast, in the nonclinical population, these are often predominantly positive and nonthreatening. The exact mechanism for the occurrence of auditory hallucinations is not yet known, but it is hoped that through the study of those in health, the mechanisms that underpin pathophysiologic processes in clinical conditions also can be elucidated.

BackgroundPatients suffering from Alzheimer’s dementia develop difficulties in social functioning. This has led to an interest in the study of “theory of mind” in this population. However, difficulty has arisen because the associated cognitive demands of traditional short story theory of mind assessments result in failure per se in this population, making it challenging to test pure theory of mind ability.MethodsSimplified, traditional 1st and 2nd order theory of mind short story tasks and a battery of alternative theory of mind cartoon jokes and control slapstick cartoon jokes, without memory components, were administered to 16 participants with mild-moderate Alzheimer’s dementia, and 11 age-matched healthy controls.ResultsNo significant differences were detected between participants with Alzheimer’s dementia and controls on the 1st or 2nd order traditional short story theory of mind tasks (p = 0.155 and p = 0.154 respectively). However, in the cartoon joke tasks there were significant differences in performance between the Alzheimer participants and the control group, this was evident for both theory of mind cartoons and the control ‘slapstick’ jokes.ConclusionIt remains very difficult to assess theory of mind as an isolated phenomenon in populations with global cognitive impairment, such as Alzheimer’s dementia, as the tasks used to assess this cognition invariably depend on other cognitive functions. Although a limitation of this study is the small sample size, the results suggest that there is no measurable specific theory of mind deficit in people with Alzheimer's dementia, and that the use of theory of mind representational models to measure social cognitive ability may not be appropriate in this population.Electronic supplementary materialThe online version of this article (doi:10.1186/2050-7283-1-28) contains supplementary material, which is available to authorized users.