Do You Match What I Match? A Systematic Review of Over 20 Years of the Emotional Face Matching Task Reveals Vast Inconsistencies in Design and Implementation.

We performed a systematic review of over 20 years of literature that implemented a variant of the emotional face matching task (EFMT). We aimed to quantify the heterogeneity in tasks used across studies, and to summarise the regions reported as activated when participants match the target face stimuli, as compared to matching the control stimuli, within and between patients with a mental health diagnosis and unaffected controls. Our results highlight the vast heterogeneity in all aspects of task design and implementation across studies. Our high-level synthesis of brain regions activated broadly confirms the involvement of the amygdala during emotional face matching, but shows that an increase in amygdala activation is inconsistent both within and across mental health conditions. We further highlight increased activation within the cingulate cortex as a transdiagnostic alteration (vs. controls) during emotional face matching. We introduce solutions to address the challenge of heterogeneity, including a standard version of the EFMT and applicable statistical methods, and provide recommendations for the field to progress our understanding of emotional face processing.