The Influence of Gaze Direction on Approach- vs. Avoidance-Oriented Emotions
When investigating the effect of gaze direction on facial expressions of emotion, previous imaging research indicated that dynamic presentation of stimuli produced higher amygdala responses (Sato, Kochiyama, Uono, & Yoshikawa, 2010). A behavioral study further suggested that approach-oriented emotions are intensified by direct gaze, where as avoidance-oriented emotions are intensified by averted gaze (Adams & Kleck, 2005). We hypothesized that direct gaze would elicit higher amygdala activity for the approach-oriented emotion of anger, where as averted gaze would elicit higher amygdala activity for the avoidance-oriented emotion of fear. Contrast estimates performed for the left and right amygdala supported our hypothesis and also displayed a lateralization effect. Approach-oriented emotions with direct gaze elicited higher responses in the left amygdala, while avoidance-oriented emotions with averted gaze elicited higher responses in the right amygdala.
The integration of facial expression of emotion and direction of gaze is an important aspect of human communication (Adams & Kleck, 2005). Facial expressions provide the outer response to changes within inner emotional states, where as gaze direction is indicative of how attention is directed and suggests behavioral intention. Previous findings implicated the amygdala as the particular region involved in the integration of emotional expression and gaze (Sato, Kochiyama, Uono, & Yoshikawa, 2010).
Sato, Kochiyama, Uono, and Yoshikawa (2010) noted inconsistent results among neural exploration of the amygdala and its role in the processing of facial expressions of emotion as a function of gaze direction. Their study attributed these differences to the type of stimulus presentation used to display the emotion. In their research, Sato et al. (2010) categorized stimulus presentation as either dynamic or static. Dynamic presentation consisted of video clips that showed a neutral expression evolving into an emotional expression of either anger or happiness, while static presentation used successive still image frames to display the change from neutral to emotional. The authors hypothesized that the integration of angry and happy emotional expressions with either direct or averted gaze would elicit higher amygdala activity in the dynamic condition than in the static condition. The results of this study supported their hypothesis and indicated the strength of dynamic presentation. Furthermore, their findings showed that both angry and happy dynamic facial expressions elicited greater amygdala activity in response to direct gaze orientation compared to averted gaze orientation.
Behavioral research by Adams and Kleck (2005) suggested that the integration of emotional expression and gaze direction implies the expressor’s behavioral intent to either approach or avoid. They suggested that the emotions of anger and happiness are categorized as approach-oriented emotions, where as the emotions of fear and sadness are defined as avoidance-oriented emotions (Adams & Kleck, 2005). Furthermore, Adams and Kleck (2005) implicated direct gaze would enhance approach-oriented emotions (anger, happiness) and averted gaze would enhance avoidance-oriented emotions (fear, sadness). Their behavioral findings indicated this effect: direct gaze increased the perceived intensity of approach-oriented expression of anger and joy, where as averted gaze increased the perceived intensity of avoidant-oriented expressions of fear and sadness.
The findings of Sato and colleagues (2010) are not clear in light of Adams and Kleck’s (2005) behavioral study. Sato et al. (2010) found greater amygdala activity for emotions of anger and happiness when combined with direct gaze compared to averted gaze. Anger and happiness, according to Adams and Kleck (2005), are approach-oriented emotions. Therefore, Sato and colleagues’ (2010) study does not investigate the integration of gaze with avoidance-oriented emotions and how this combination influences amygdala activity. Furthermore, Harmon-Jones and Sigelman (2001) explored the effects of both approach-oriented and avoidance-oriented affect and suggested a lateralization of activity. Their EEG study implicated greater left-hemisphere responses to be associated with processing anger, an approach-oriented emotion, and right hemispheric activity to be more connected to fear, an avoidance-oriented emotion.
Based upon the findings of Sato et al. (2010) and Adams and Kleck (2005), we investigated the neural bases of both approach- and avoidance-oriented emotions with regards to gaze direction. We used the dynamic presentation of stimuli adapted from Sato and colleagues (2010) due to the elicitation of higher amygdala activity compared to the static presentation. Our study contained the approach-oriented emotion of anger and the avoidance-oriented emotion of fear because each affect is negative and produced the most salient responses in their respective studies. We hypothesized that the amygdala response to anger stimuli with direct gaze would be higher than that of anger stimuli with averted gaze. Furthermore, we expected the amygdala response to fear stimuli with averted gaze would be higher than that of fear stimuli with direct gaze. Based upon the findings of Harmon-Jones and Sigelman (2001), we also predicted a lateralization of activity within the amygdala, with the left amygdala eliciting higher responses to the approach-oriented emotion of anger and the right amygdala eliciting greater activity for the avoidance-oriented emotion of fear.
Behavioral data analysis