Résumé : Behavioural studies have used spatial cueing designs extensively to investigate emotional biases in individuals exhibiting clinical and sub-clinical anxiety. However, the neural processes underlying the generation of these biases remain largely unknown. In this study, people who scored unusually high or low on scales of social anxiety performed a spatial cueing task. They were asked to discriminate the orientation of arrows appearing at the location previously occupied by a lateralised cue (consisting of a face displaying an emotional or a neutral expression) or at the empty location. The results showed that the perceptual encoding of faces, indexed by P1, and mobilisation of attentional resources, reflected in P2 on occipital locations, were modulated by social anxiety. These modulations were directly linked to the social anxiety level but not to trait anxiety. By contrast, later cognitive stages and behavioural performances were not modulated by social anxiety, supporting the theory of dissociation between efficiency and effectiveness in anxiety.