L A A LCALDÍA I NDÍGENA EN PROCESO DE CAMBIO

In all three conditions, participants exhibited a GOE. However, this GOE was largest in the more ecologically valid condition (Condition 2), and reflected the combined effects of a faster response to congruent targets and a slower response to incongruent targets in Condition 2 compared to Conditions 1 and 3. The use of a more ecological stimulus sequence (Condition 2) could thus potentiate attention to gaze by both enhancing engagement to the gazed-at location and hindering disengagement from this location.

Our main goal was to determine which cue sequence would enable the congruency effect to be influenced by emotions. Only in Condition 2, in which the cue averted its gaze before expressing an emotion, did we find an enhancement of the GOE with angry, fearful and surprised facial expressions compared to neutral expressions. Thus, the type of cue used in this Condition 2 seems best suited to study the impact of emotions on gaze-oriented attention. It is more naturalistic as in real settings one tends to react to a stimulus after orienting towards it. It is also possible that the short presentation of an emotion in that sequence (300ms compared to 800ms in Condition1 and 500ms in Condition 3) enabled a particular sensitivity to the expressive face. Finally, in Condition 2, the gaze shift is independent of facial

expression so it is not confounded by the differences of eye aperture between the various emotions (Graham et al., 2010).

The eye size has been shown to enhance the gaze orienting effect to some extent (Bayless et al., 2011; Tipples, 2006), so we expected to find an enhanced modulation of the GOE with emotions in which the sclera was enlarged (fear and surprise) in Conditions 1 and 3. Indeed, in those conditions, the gaze shift was confounded with the eye aperture associated with emotion (as it occurred after or together with the emotion onset). Fearful and surprised faces are characterized by wide open eyes so it is easier to process a change in the gaze direction with those emotions compared with happy faces, for which the eyes are squinted. On the contrary, we found that the GOE was only modulated in Condition 2 where the gaze shift occurred in a neutral face and thus was not confounded by eye aperture. Our results suggest that eye aperture is not a critical factor in the modulation of gaze-oriented attention with emotional faces. In

accordance with those results, other studies in which the cueing stimulus consisted of a facial stimulus averting its gaze before expressing an emotion also yielded a modulation of the GOE with emotions (Graham et al., 2010; Neath et al., 2013).

The lack of GOE modulation by emotions when gaze was averted after or simultaneously with emotion onset (Condition 1 and Condition 3 respectively) is consistent with most studies in which similar designs have been used (Fichtenholtz et al., 2007; 2009; Galfano et al., 2011; Hietanen & Leppänen, 2003; Holmes et al., 2010; Mathews et al., 2003). The fact that a modulation of attention to gaze with emotions was observed in Chapter 3 is interesting. Indeed, the exact same sequence as in Condition 3 was used in Chapter 3 except that only three emotions were included in each condition (fear, surprise, neutral for the FSN condition and happy, angry, neutral for the HAN condition). This suggests that the affective context in which an emotion is presented might influence its ability to impact attention to gaze. Using a similar sequence to Condition 3 (a neutral face with straight gaze immediately followed by a frame showing the emotional face with averted gaze or by a succession of frames representing the face gradually shifting its gaze and expressing an emotion), several authors (Putman et al. 2006; Tipples et al., 2006; Uono et al., 2009) found an enhancement of the GOE with fearful faces relative to neutral faces.

However, their results are difficult to interpret because high anxious participants were included and it has been shown that anxiety influences the way in which emotion modulates gaze-oriented attention

(Mathews et al., 2003; Putman et al., 2006; Tipples, 2006).

Our findings are crucial for future experiments that will investigate the impact of emotion on the gaze orienting effect. Indeed, if researchers are interested in the role of emotional gaze in social interaction, it will be in their best interest to use the more ecologically valid cue sequence that was used in Condition 2, which conclusively shows that gaze can be modulated by emotion in a non-anxious population. However, we acknowledge several limiting factors in this experiment which future studies will have to address. First, it will be important to use a different non-directional cue than a face with direct gaze, which

includes some facial movement to determine whether some of the observed effects were due to the lack of movement in our direct gaze neutral condition. Second, it will be important to test the influence of the presentation time of facial expression on attention to gaze, as, despite a constant SOA of 500ms, this parameter differed between our three conditions, with the emotion being expressed for 800ms in

Condition 1, for 300ms in Condition 2 and for 500ms in Condition 3. It will also be crucial to determine whether or not the time elapsing between the last change in the stimulus sequence and the target onset is

an important factor, as it varied between experiments in the present study (500ms for Condition 1 and Condition 3 but 300ms for Condition 2). Finally, it will be important to determine the affective context in which one emotion could enhance the GOE compared to neutral faces. Indeed, even though we used the exact same experimental design in Condition 3 as used in Chapter 3, we failed to show a statistically significant enhancement of the GOE with fearful, surprised and angry faces compared to neutral faces in Condition 3 while a significantly larger GOE for fearful, surprised and angry faces compared to neutral faces was found in Chapter 3.

4.5.2 Enhanced GOE for fear, surprise and anger: facilitation of engagement or