Increased generalisation in trait anxiety is driven by value transfer, not reduced perceptual discrimination

Anxiety has been linked to increased generalisation of threat expectations to stimuli that areperceptually similar. Such generalisation can arise either from a failure to distinguishbetween threatening and non-threatening stimuli (perceptual mechanism) or from thetransfer of learned values between stimuli (value-based mechanism). Despite importantimplications for treatment, how these two mechanisms contribute to generalisation, andwhether they are differentially impacted by anxiety remains unclear. Here, we combine a setof novel experimental and computational approaches to dissociate perceptual andvalue-based contributions to generalisation. Participants (N = 140) first underwent anextensive titration procedure that resulted in personalised stimulus spaces matched inperceived similarity across participants. These stimuli were then used in aversiveconditioning and generalisation tasks while we varied outcome probability anddiscriminability. Using computational modelling, we show that some participants generalisedue to a perceptual mechanism, while others due to value-based mechanisms. Further, weshow that trait anxiety is associated with stronger generalisation to stimuli that are mostdissimilar from the conditioned stimulus and that this effect is driven by greater reliance onvalue transfer, rather than an inability to discriminate stimuli. These results generate keynovel insights into the nature of generalisation and how trait anxiety impacts generalisationat the level of cognitive mechanisms.