Stage 2 Registered Report: Propositional Thought Is Sufficient for Imaginal Extinction as Shown by Contrasting Participants With Aphantasia, Simulated Aphantasia, and Controls.

Imaginal exposure is a standard procedure of cognitive behavioral therapy for the treatment of anxiety and panic disorders. It is often used when in vivo exposure is not possible, too stressful for patients, or would be too expensive. The Bio-Informational Theory implies that imaginal exposure is effective because of the perceptual proximity of mental imagery to real events, whereas empirical findings suggest that propositional thought of fear stimuli (i.e., thinking about the stimuli without seeing them in the mind's eye) could be sufficient. To investigate whether mental imagery or propositional thought is crucial for the success of imaginal exposure, participants with the rare state of aphantasia (= absence of sensory mental imagery) and two control groups were subjected to a fear conditioning paradigm followed by imaginal exposure and a reinstatement procedure. During imaginal exposure, a control group (N = 30) stared at a bright screen to disrupt visual imagery by incoming luminance (=simulated aphantasia), while a second control group (N = 30) and participants with actual aphantasia (N = 30) kept their eyes closed. Results showed successful extinction in all groups, thus demonstrating that imaginal extinction is possible using propositional thought. Moreover, exploratory analyses revealed less subjective fear in people with aphantasia during the fear conditioning procedure, potentially due to similar mechanisms as in alexithymia, that is, a decoupling between physiological arousal and emotional experience.