Perception , Emotions and Delusions : Revisiting the Capgras ' Delusion

The study of delusions has important implications for understanding the role played by affective processes on the road from experience to belief. It can also shed light on the forms of modularity these processes manifest. There are at least two different ways in which emotional processes may be relevant to the etiology of delusional beliefs. First, current models of delusion converge in proposing that such beliefs are based on unusual experiences of various kinds. These unusual experiences are thought to include affective or emotional experiences. For example, it is argued that Capgras' delusion (the belief that a known person has been replaced by an impostor) is triggered by an abnormal affective experience in response to seeing a known person (Ellis & Young, 1990). Similarly, the Cotard delusion (which involves the belief that one is dead or unreal in some way) may stem from a general flattening of affective responses to external stimuli (Ellis & Young, 1990), while the seed of the Frégoli delusion (the belief that one is being followed by known people who are in disguise) may lie in heightened affective responses to unfamiliar faces (Davies et al, 2001). In 2 delusions of persecution, the experiential component could be an over-sensitivity to other people's disingenuous expressions of emotions (LaRusso, 1978; Davis & Gibson, 2000). Experience-based proposals have been provided for a number of other delusions (Stone & There is also a second way in which emotional processes may be relevant to the aetiology of delusional beliefs, for one must also explain why these abnormal experiences give rise to delusional beliefs and why these delusional beliefs are "firmly sustained despite what almost everyone else believes and despite what constitutes incontrovertible and obvious proof or evidence to the contrary" (DSM-IV-TR, 2000, p. 821). Although current models of delusion converge in proposing that delusions are based on unusual experiences, they differ in the role that they accord experience in the formation of delusions. On some accounts, the experience comprises the very content of the delusion, whereas on other accounts the delusion is adopted in an attempt to explain an unusual experience. I call these the endorsement and explanationist models respectively (see Bayne & Pacherie, 2004a, 2004b). Emotional factors may also contribute to such an explanation. In the present paper, I will focus on Capgras' delusion. Three reasons motivate this choice. First, central to this delusion is an emotion or rather a pair …