This is the fifth and final post in a series of posts on the papers published in an issue of Avant on Delusions. Here Glenn Carruthers (pictured above) summarises his paper 'Difficulties for Extending Wegner and Colleagues' Model of the Sense of Agency to Deficits in Delusions of Alien Control'.
When I reach my hand for the comb it is my hand and arm which move, and my fingers pick up the pen, but I don’t control them… I sit there watching them move, and they are quite independent, what they do is nothing to do with me… I am just a puppet who is manipulated by cosmic strings. When the strings are pulled my body moves and I cannot prevent it. (Mellor 1970: 18)
Perhaps part of the reason such patients think someone is controlling them is that they do not have this normal sense of agency. To investigate this further we would like to know how the sense of agency is elicited and why it is deficient in these cases. There have been a bunch of hypotheses developed to explain this. Here I will focus on one which was developed by Daniel Wegner and his collaborators (Wegner et al 2004; Wegner and Wheatley 1999).
Wegner and colleagues' hypothesised that the sense of agency is elicited when a subject (unconsciously) infers that one or other of their mental states (e.g. an intention) caused their action. This is called the inference to apparent mental state causation and it occurs automatically when three principles are met:
Priority: The mental state occurs at an appropriate time prior to the action.
Consistency: The mental state is consistent with the action (e.g. the intention specifies the action that actually occurred).
Exclusivity: The mental state is the only plausible cause of the action.