The physiological response to implicit and explicit fear faces in alexithymia

Alexithymia is a form of disordered emotional processing associated with psychiatric illness and poor treatment outcomes. Its hallmarks are difficulty identifying, representing and evaluating emotional material. Research on alexithymia includes investigations of behavioral, physiological and neural responsivity. Findings within and between these different methodologies are inconsistent and often not well motivated. We use the neuroimaging literature to motivate a design that links behavior and physiology in alexithymia. The aims of this study are to determine: 1) whether individuals with alexithymia exhibit behavioral responses to emotional faces that differ from controls and whether there are corresponding changes in physiology, 2) whether behavioral and physiological responses in alexithymia are differentially influenced by an implicit versus explicit manipulation of emotional task context, compared to controls. For Aim 1, we measure behavioral and physiological responses during two explicit facial categorization tasks: an emotion task requiring categorization of morphed emotional facial expressions, and an identity task requiring categorization of morphed facial identities. For Aim 2, we evaluate responses to emotional and neutral facial expressions in two task contexts: in an explicit task participants label the emotion of the face, while in an implicit task participants label the gender of the face. Using these experiments we determined whether undergraduates scoring high or low on alexithymia (TAS-20) differ on accuracy, reaction time, heart rate and skin conductance. Counter to prevailing theories of alexithymia as an appraisal problem, we found that alexithymia participants task accuracy on emotional and non-emotional tasks is intact. We found less sensitivity to fearful faces during an emotion categorization task, but not a non-emotional identity categorization task, as we expected. In alexithymia, we found less sensitivity to emotion and altered heart rate reactivity during implicit and explicit tasks, compared to healthy controls. Counter to current conceptualizations of alexithymia as a difficulty engaging in top-down appraisal of emotional information, our findings suggest that alexithymia may be a problem generating physiological responses to emotional information. Based on our view of alexithymia, we revisit the current state of the alexithymia literature, provide suggestions for future research and propose potential therapeutic interventions