Alexithymia and automatic processing of emotional stimuli: a systematic review.

Alexithymia is a personality trait characterized by difficulties in recognizing and verbalizing emotions and the utilization of a cognitive style that is oriented toward external events, rather than intrapsychic experiences. Alexithymia is considered a vulnerability factor influencing onset and course of many psychiatric disorders. Even though emotions are, in general, elicited involuntarily and emerge without conscious effort, it is surprising that little attention in etiological considerations concerning alexithymia has been given to deficits in automatic emotion processing and their neurobiological bases. In this article, results from studies using behavioral or neurobiological research methods were systematically reviewed in which automatic processing of external emotional information was investigated as a function of alexithymia in healthy individuals. Twenty-two studies were identified through a literature search of Psycinfo, PubMed, and Web of Science databases from 1990 to 2016. The review reveals deficits in the automatic processing of emotional stimuli in alexithymia at a behavioral and neurobiological level. The vast majority of the reviewed studies examined visual processing. The alexithymia facets externally oriented thinking and difficulties identifying feelings were found to be related to impairments in the automatic processing of threat-related facial expressions. Alexithymic individuals manifest low reactivity to barely visible negative emotional stimuli in brain regions responsible for appraisal, encoding, and affective response, e.g. amygdala, occipitotemporal areas, and insula. Against this background, it appears plausible to assume that deficits in automatic emotion processing could be factors contributing to alexithymic personality characteristics. Directions for future research on alexithymia and automatic emotion perception are suggested.