**3.4 N170/Vertex Positive Potential (N170/VPP)**

The N170/VPP complex is a negative peak around 170 ms in the temporal-occipital regions and simultaneously one central-frontal positivity (VPP), functionally equivalent (Joyce and Rossion, 2005). The source of N170 compromises the inferior temporal gyrus and the fusiform gyrus (two neural areas associated with specific face processing). Its amplitude is greater for human faces, compared with objects or other stimuli (Bentin, Allison, Puce, Perez and McCarthy, 1996; Jeffreys, 1989). During the face-processing task, N170 is sometimes followed by a P2, a N250 and an LPP component modulated by other variables. The N170 component has shown amplitude/latency modulation based on race cues (Ibanez et al., 2010c; Ito and Ulrand, 2005; Gonzales et al., 2008), emotional variables (Ashley, Vuilleunier and Swick, 2004) and contextual effects (Ibanez et al. 2011d).

#### **3.5 Early Posterior Negativity (EPN)**

The EPN is a middle-latency component that has been associated with different stages of valence information processing and affective discrimination (Schupp et al., 2004a, 2004b). Di Russo, Taddei, Apnile and Spinelli (2006) suggested that EPN would reflect early valence discrimination and response selection processes. Additionally, Schupp et al. (2004a) have stated that the processing indexed by the EPN is modulated by perceptual features that facilitate further evaluation of arousing stimuli. Different studies have found a modulation differing from the neutral for both emotional (pleasant, unpleasant) categories of pictures (e.g., Dufey et al., 2010; Cuthbert, Schupp, Bradley, Birbaumer and Lang (2000). Nevertheless, specific effects (task or stimuli-dependent) on EPN in relation to valence and the influence of arousal should be further assessed.

### **3.6 P300 (or P3)**

This component has been described as engaging higher-order cognitive operations related to selective attention and resource allocation (Donchin and Coles, 1988). The P3 amplitude may serve as a covert measure of attention that arises independently of behavioral responding (Gray et al., 2004). The component has also been related to a post-decisional "cognitive closure" mechanism (Desmedt, 1980; Verleger, 1998); and to the access of information for consciousness (Picton, 1992). Its amplitude generally varies as a function of the temporal distance between a target and a preceding outgoing stimulus (e.g., Cornejo et al., 2007). There are two sub-components (P3a and P3b). The P3a has a more frontal distribution and is observed after an unexpected event, regardless of the relevance of the stimulus. Usually, it is associated with automatic attentional modulation. The P3b is related to attention, working memory and superior cognitive functions and is observed at centro-parietal sites. This ERP is affected by several psychological processes, the most important of which are motivation and sustained attention.
