26 Chapter 2 stimulus (e.g., an angry facial expression directed at him/her), he/she will engage in an automatic defensive freeze and flight-or-fight response, a quick and automatic sequence of defensive responses stages (Bradley, Codispoti, Cuthbert, & Lang, 2001). During threat exposure in particular, an initial freezing response is activated during which the individual ceases all ongoing activity and perception is enhanced to quickly assess the situation in order to optimize subsequent fight-or flight responses (Blanchard, Griebel, Pobbe, & Blanchard, 2011; Lojowska, Gladwin, Hermans, & Roelofs, 2015; Roelofs, Hagenaars, & Stins, 2010). This is an automatic process, and the evaluation directly results in a behavioral disposition towards the stimulus: aversive stimuli generally elicit the tendency to move away from the stimulus and appetitive stimuli will elicit a tendency to move towards the stimulus (Lang, Bradley, & Cuthbert, 1997). Such automatic tendencies can also influence more complex, instrumental approach–avoidance decision making (Geurts, Huys, den Ouden, & Cools, 2013; Guitart-Masip, Duzel, Dolan, & Dayan, 2014). For instance, Ly, and colleagues (2014) tested such influence in 45 healthy human individuals using an experimental set-up in which automatic freezing reactions towards negatively (versus positively) valenced stimuli were disentangled from instrumental approach–avoidance decisions (guided by monetary rewards and punishments). Critically, the transfer of valence (and related automatic reactions) to the instrumental approach–avoidance actions were systematically tested. The valence of angry (versus happy) faces was indeed found to transfer to instrumental decision making, in such a way that it induced an instrumental avoidance bias. The extent of freezing elicited by the angry faces was significantly correlated to the instrumental avoidance bias. Both automatic freeze–fight–flight tendencies and more instrumental approach and avoidance biases have been suggested to play a prominent role in the maintenance and perhaps even cause of psychopathology (Blanchard et al., 2011; Rudaz, Ledermann, Margraf, Becker, & Craske, 2017; Turk, Lerner, Heimberg, & Rapee, 2001; Wong & Moulds, 2011). Aggression, for instance, has been conceptualized as a defensive response system in which automatic fight - responses are triggered too easily and in which instrumental threat– approach tendencies become well-learned and rewarded (Blair, 2013; Blanchard et al., 2011; Ly et al., 2016). On the contrary, persistent avoidance in anxiety disorders has been thought of as a defensive response system in which automatic flight –response are easily triggered and in which instrumental threat– avoidance tendencies become rewarded and well learned (Blanchard et al., 2011). Rolls, (2000) emphasized the importance of facial expressions as input for these systems, as they convey social information. When applied in social approach–avoidance tasks (AATs), healthy people show a general tendency to move away from angry expressions and to approach happy faces (Bradley et al., 2001; Chen & Bargh, 1999; Heuer et
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