Transmitting and Decoding Facial Expressions

Abstract

This article examines the human face as a transmitter of expression signals and the brain as a decoder of these expression signals. If the face has evolved to optimize transmission of such signals, the basic facial expressions should have minimal overlap in their information. If the brain has evolved to optimize categorization of expressions, it should be efficient with the information available from the transmitter for the task. In this article, we characterize the information underlying the recognition of the six basic facial expression signals and evaluate how efficiently each expression is decoded by the underlying brain structures.

Atypical information-use in children with autism spectrum disorder during judgments of child and adult face identity

“…This information was used even though the mouth was not particularly helpful for discriminating between these two particular identities (confirmed by the saliency model). Such a bias to draw information from the mouth is very much in line with other published work on information use during face judgments, which is suggested to be broadly optimized to support face expertise (Smith, Cottrell, Gosselin, & Schyns, 2005). We speculate that across their extensive face experience accumulated from infancy, typical individuals might develop a “default” face processing strategy, which is then flexibly adapted to match stimulus characteristics and task demands but was not wholly recalibrated in the 216 trials of the current study.…”

The Role of Alexithymia in Reduced Eye-Fixation in Autism Spectrum Conditions

“…R 2 values indicated on each graph scan paths of the eyes and mouth may be unrelated to autism diagnosis, but instead are determined (in part) by the degree of co-morbid alexithymia in the sample of individuals with autism. Second, many studies have demonstrated the importance of typical scan paths in recognising facial emotion (Aviezer et al 2008;Calder et al 2000;Smith et al 2005;Wong et al 2005), therefore if alexithymia is associated with atypical scan paths to eyes and mouth, then the inconsistent findings with respect to recognition of emotional facial expression in autism (see Bal et al 2010;Jemel et al 2006) may also be explained by varying degrees of co-morbid alexithymia in the sample of individuals with autism across studies. We suggest therefore, that future studies of emotion processing in individuals with autism obtain measures of alexithymia in order to determine whether any impairments seen are due to autism, alexithymia, or the combination of these two factors.…”

“…More generally, many studies show that in order to accurately categorize observed emotional expressions one must appropriately scan eye and mouth features, as different emotional expressions are most reliably signalled by different parts of the face (Aviezer et al 2008;Calder et al 2000;Smith et al 2005;Wong et al 2005).…”

“…Several studies support this conjecture, reporting impaired recognition of facial emotion in alexithymia (Mann et al 1994;Parker et al 1993;Jessimer and Markham 1997;Lane et al 1996Lane et al , 2000Prkachin et al 2009). The reliance of accurate emotion recognition on typical visual scan paths to emotional face stimuli (Aviezer et al 2008;Calder et al 2000;Smith et al 2005;Wong et al 2005), makes it possible that the impaired emotion recognition in individuals with alexithymia is due to atypical attention to the eye and mouth regions of emotional face stimuli. As far as we are aware, no previous study has examined visual scan paths in individuals with alexithymia (irrespective of autism diagnosis).…”

“…Findings of impaired emotion recognition in individuals with alexithymia but without autism raise the possibility that levels of co-morbid alexithymia in individuals with autism determine the appropriateness of visual scan paths to emotional faces, particularly eye:mouth ratios which have been shown to be important for recognising emotion (Aviezer et al 2008;Calder et al 2000;Smith et al 2005;Wong et al 2005). Varying degrees of co-morbid alexithymia across studies may therefore explain the heterogeneity of findings in relation to atypical eye:mouth fixation behaviour in autism.…”