Effects of facial expressions on visual short-term memory in relation to alexithymia traits

We examined dysfunctional memory processing of facial expressions in relation to alexithymia. Individuals with high and low alexithymia, as measured by the Toronto Alexithymia Scale (TAS-20), participated in a visual search task (Experiment 1A) and a change-detection task (Experiments 1B and 2), to assess differences in their visual short-term memory (VSTM). In the visual search task, the participants were asked to judge whether all facial expressions (angry and happy faces) in the search display were the same or different. In the change-detection task, they had to decide whether all facial expressions changed between successive two displays. We found individual differences only in the change-detection task. Individuals with high alexithymia showed lower sensitivity for the happy faces compared to the angry faces, while individuals with low alexithymia showed sufficient recognition for both facial expressions. Experiment 2 examined whether individual differences were observed during early storage or later retrieval stage of the VSTM process using a single-probe paradigm. We found no effect of single-probe, indicating that individual differences occurred at the storage stage. The present results provide new evidence that individuals with high alexithymia show specific impairment in VSTM processes (especially the storage stage) related to happy but not to angry faces.