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If the magnitude of the GOE is quite small (between 8 and 30ms across studies), its emotional

modulation is even smaller (5ms on average in this thesis) and influenced by the experimental design (i.e., SOA, face cue sequence, possibly number/type of emotions included). In addition, the GOE is only an indirect measure of gaze-oriented attention, as it reflects processes that occurred after cue presentation as well as during and after target presentation. Event Related Potentials (ERPs) can be used to track these processes directly when they take place. In Chapters 3 and 5, we demonstrated that ERPs could reliably index the stages involved in attention orienting to gaze.

Importantly, the experiments presented in Chapters 3 and 5 are the first gaze cueing studies to report the presence of both attention-related EDAN and ADAN components recorded to the cue, despite variations in the paradigms used, which attests to the reliability of these findings. EDAN indexes attention-orienting to the gazed-at location, while ADAN, occurring later, reflects holding of attention at a gazed-at location. Previously, these components had been reliably shown only with symbolic cues (e.g., Praamstra et al., 2005). A study contrasting gaze and symbolic cueing, found the presence of EDAN and ADAN for arrow cues but not for gaze cues (Hietanen et al., 2008). However, the gaze cues were embedded in overly schematic pictures of faces, a stimulus that might not have been realistic enough to elicit the same processes as gaze perceived from face photographs. Using pictures of real emotional faces in a discrimination task, Holmes and colleagues (2010) showed the presence of ADAN but not EDAN in a gaze cueing paradigm. The fact that we observed both ADAN and EDAN when using pictures of real emotional faces and the more ecologically valid localization task, suggests that task might impact the processes recruited for gaze-oriented attention. We argue that a localization task is more ecologically valid as one usually orients toward a location before assessing what is present at that location. In any case,

our results suggest that similar attention stages, as revealed by these two ERP components, can be seen in both symbolic and gaze cueing paradigms. The finding of EDAN/ADAN presence for arrow cues but not gaze cues led some to argue that eyes are special in engaging attention and rely on a different attention- orienting mechanism than arrows (e.g., Hietanen et al., 2008). The presence of both components for gaze cues reported in this thesis questions this assumption. Given that EDAN and ADAN are characteristic of symbolic cueing known to rely on voluntary or endogenous attention (see section 1.1.3), our results suggest that the early stages of gaze cueing might also rely on endogenous attention. This idea is in accordance with previous evidence demonstrating similarities between arrow and gaze cueing (see Frischen et al., 2007 for a review). However, caution is required given arrow and gaze cues were not compared in a single experiment in this thesis. Future studies will need to compare the ERPs elicited by both types of cueing in the same experiment for more conclusive evidence of similarities and differences in the processes engaged by arrow and gaze cueing.

In addition to cue-triggered ERPs, we also investigated the modulations of the P1 component triggered by the presentation of targets as a function of gaze congruency and preceding emotion cue. In accordance with previous findings (Schuller & Rossion, 2001, 2004, 2005), P1 exhibited larger amplitudes in the congruent condition than in the incongruent condition, across two different experiments. Planned

comparisons revealed that this effect was found for targets preceded by emotional faces but not by neutral faces, a finding interpreted as reflecting an effect of the emotional context in which neutral faces were presented. Overall, this P1 congruency effect indicates an enhancement of visual processing at the cued location (Hopf & Mangun, 2000). However, we did not find an earlier P1 latency in the congruent

compared to the incongruent condition, as reported previously with neutral face cues (Schuller & Rossion, 2001; 2004; 2005). Instead, using emotional faces, we showed that P1 occurred later in the congruent than in the incongruent condition (although in Chapter 5 this effect was restricted to inverted faces). This was the first report of a congruency effect on both P1 amplitude and latency in gaze cueing experiments using emotional faces. The reliability of these effects (especially latency) will thus have to be assessed by future studies.

No emotional modulation of EDAN and ADAN was found in either study, suggesting that, at the brain level, gaze-oriented attention is not modulated by emotion in the first 500ms after gaze shift. In contrast, emotion modulates the P1 congruency effect compared to neutral faces but the emotional modulations of the congruency effect on P1 (for happy, fearful and surprised faces) do not yet reflect the emotional

modulation of the GOE seen at the behavioral level (for fearful, surprised and angry faces). Thus, we conclude that, in both studies, further emotional modulation of the neural processes associated with gaze- oriented attention occurs between the P1 (~100ms after target onset) and the behavioral response (~300ms after target onset), that is, between 600-800ms after gaze cue onset (which always occurred 500ms after gaze cue onset), which is fairly late.

6.2.3 Autistic traits influence gaze oriented attention and its modulation by facial