Delusion-prone individuals : stuck in their ways?

Although false memories and confabulation have been linked to both executive dysfunction and greater suggestibility, similar associations with the emergence of delusional thinking remain unexamined. We therefore compared healthy individuals who scored high and low on the Peters Delusional Inventory (PDI: Peters et al., 1999) on measures of set-shifting (the intra–extradimensional set shift task: IED) planning (the Stockings of Cambridge Task: SOC). Additionally, we examined whether high delusion-prone individuals show greater suggestibility on the Gudjonsson Suggestibility Scale (GSS 2: Gudjonsson, 1987). On the IED task, the high group made more pre-extradimensional shift errors than the low PDI group, and this was especially notable for reversal learning. By contrast, no differences emerged on any aspect of the SOC. Finally, and intriguingly, the high PDI group was less likely than the low PDI group to change their responses after receiving suggestive negative feedback. We propose that delusional-style thinking may be underpinned by an orbitofrontal-based reversal learning difficulty affecting the flexibility to adapt responses to changing contingencies and external pressure.