The role of interference in identification of emotional facial expressions in normal ageing and dementia

Abstract

In normal daily life, the identification of emotional facial expressions (EFEs) usually takes place simultaneously with other demands, requiring working memory resources. In the current study, the authors investigate the role of the interference caused by a secondary task in emotional facial identification. The decline in performance in a given task when adding a secondary task may be one of the strongest variables differentiating between normal and pathological ageing. The goal of the current study was to assess to what extent processing of EFEs is affected when cognitive resources are experimentally (over)loaded. Three groups of participants (Alzheimer's patients, healthy older adults, and healthy young adults) had to identify six basic emotions under two conditions: identification-only and identification with a visual secondary task. The results showed a decrease in performance of EFEs identification when the processing of this mental image was interfered by another visual stimulus, for all groups. When computing the dual-task costs, AD patients showed higher costs than older and young adults, revealing that dementia but not ageing itself, is more vulnerable to interference effects. This study reveals further data supporting the hypothesis of a top-down control in emotional processing and offers a new approach to understand EFEs identification in analogous real-life conditions and reveals how this processing is differentially affected by ageing and dementias.