Background:
Although delusions of reference are one of the most frequently occurring symptoms of psychosis, they have been the focus of little research. Only one theory has been advanced to explain them and this theory has not received consistent empirical support. Recent research has suggested there are two different kinds of delusion of reference: delusions of communication and delusions of observation, and only the latter is associated with hallucinations and persecutory ideation. Delusions of communication may derive from difficulties with self-monitoring, whereby what seems to be communicated concerns the self and originates from the self, although the origin is not recognized but attributed externally.
Methods:
This theory was tested with people suffering an acute psychotic episode (n = 63) using a visual signal detection task. Participants were required to distinguish between video clips of gestures and nonges-tures under conditions of uncertainty (visual noise).
Results:
The previous finding of two kinds of delusions of reference was replicated. A signal detection analysis showed that people with delusions of communication were no less sensitive to gestures than people with psychosis without these delusions but showed a significantly greater bias toward perceiving them. Whether people had auditory hallucinations or not made no difference to their sensitivity or bias.
Conclusions:
It is suggested that bias to perceive gestures occurs because people misattribute self-generated events to an external source. However, this bias is not part of a general tendency to externalize one's own thoughts but may be specific to delusions of communication.
