Abstract
The perceptual strength of a facial expression is widely shaped by context. Binocular rivalry (BR) has proven to be a promising tool in studying face perception. It involves the alternation between two stimuli that are simultaneously, but monocularly, presented. BR is postulated to occur due to inhibitory interactions between neuronal populations tuned for the presented stimuli. Therefore, BR provides a reflection of perceptual strength, whereby shorter stimulus perception (dominance duration) signifies greater inhibition and weaker tuning. We previously demonstrated that, while there may be an interaction between the identity and emotion portrayed by face stimuli during BR, emotion has a stronger influence and thus holds greater perceptual strength. Moreover, positive emotions tend to dominate over negative ones. To assess whether perceptual strength is also dependent on the intensity of an emotion (valence), 3D natural-looking face identities of similar skin tone and gender were created in FaceGen Modeller to express five emotions (very happy, happy, neutral, sad, and very sad) and were set to rival as 29 human subjects reported which stimulus they perceived throughout a trial. Prior BR studies that investigated valence-dependence were confounded by stimuli discrepancies that highlight certain local facial features over others. Here, extreme emotions were portrayed through the use of Duchenne eye constrictions, which permitted control over feature-salience across stimuli. Subjects reported that extreme emotions were perceived for significantly greater dominance durations than basic ones (p < 7.91x10-7, Kolmogorov-Smirnov [KS]). Furthermore, when the same stimuli were inverted and rivaled, all dominance durations were rendered insignificantly different from one another (p > 0.11, KS). This verifies that the observed significance using Duchenne characteristics was not driven by the local feature—eye wrinkles, but rather by the global emotion portrayed. Overall, the more intense an emotion, the greater its perceptual strength and possibly the higher its processing priority during BR.
Meeting abstract presented at VSS 2015