1350 MARATOS, MOGG, BRADLEY terms of its arousal-provoking properties. Recent research that has used verbal, rather than pictorial, stimuli as targets suggests that the arousal value of word stimuli is an important determinant of the extent of the AB (Anderson, 2005; Keil & Ihssen 2004). In order to investigate further the relative influences of stimulus valence and arousal on attentional mechan- isms, it may be helpful to use real-life pictorial representations of emotional faces, because real-life faces not only have good ecological validity, but also a potentially wider range of emotional valence and arousal values for both threatening and positive facial expressions, relative to schematic faces. Another interesting finding from the present study was that, although the AB on trials with threat T2 faces was attenuated relative to trials with neutral T2 faces, there was still evidence of a residual AB for threat faces. That is, the results indicated an impaired ability to identify the threat T2 when it appeared at a short lag (T1 T2 SOA of 257 ms) relative to when it appeared at later lags (T1 T2 SOAs ranging from 643 1157 ms). The pattern of means in Fox et al. (2005) and Milders et al. (2006) similarly suggest that the AB effect was attenuated, rather than eliminated, by fearful faces (i.e., identification of fearful T2 faces appeared to be poorer at early lags compared with later time lags). Thus, one research question that remains to be addressed is whether the AB effect would be abolished entirely when more aversive stimuli are used, such as real-life stimuli depicting intense anger. Given that the present results support the hypothesis that threat stimuli are accorded higher priority (relative to neutral stimuli) when there is competition for processing resources, it is helpful to consider the mechan- isms that may underlie such emotional influences on the AB. A dominant theoretical view is that performance decrements associated with the AB arise because the two targets (T1 and T2) and their immediately following distractor stimuli compete for access to a limited supply of processing resources (Shapiro et al., 1997a). Anderson (2005) recently reviewed several ways in which emotional stimuli might ‘‘win’’ in this competition. For example, the cognitive representations of emotional stimuli in short-term memory may persist longer than those of neutral stimuli, which would allow them an advantage in subsequent processing. Alternatively, threat cues could be processed automatically (LeDoux, 1996) and consequently place less demand on processing resources in order to reach awareness. Third, emotional stimuli may activate a network of neural structures, including the amygdala, prefrontal and sensory cortices, which in turn modulate attention and visuo-perceptual processing, resulting in enhancement of the subjective perceptual experience of threat cues and their ability to capture attention (e.g., Davis & Whalen, 2001; Vuilleumier, 2005). Recent research has indicated that, within the time window of the AB, healthy individuals who have intact amygdalae are better at detecting aversive words than neutral words; whereas patients with left amygdala