Abstract:

The Distractor Previewing Effect (DPE) is one of the inter-trial effects in visual search based on features or categories. In the DPE tasks, oddball-present and oddball-absent trials are intermixed to present. The target is defined by one feature (e.g., a green diamond among red ones) or category (e.g., a face picture among house pictures), and the response is defined by another feature, such as the shape of the color oddball or which side of the face pictures has a red dot next to it. The DPE is indicated by faster responses on the current oddball-present trial when the distractors are congruent with the stimuli on the preceding oddball-absent trial than when the target does so. Both behavioral and neuroscience studies have revealed that the DPE reflects an attentional bias caused by past unsuccessful experience. In this study, participants were shown three emotional stimuli on each display, with or without one picture having a different valence from the other two. They searched for this emotional oddball and identified its non-affective feature if an oddball was present. If the RTs on the current oddball-present trial are faster when the valence of the target is congruent with that of the stimuli on the preceding oddball-absent trial than when the target does so, this inter-trial effect is the emotional DPE. Pictures of veridical faces of emotional expressions were shown in Experiment 1, whereas pictures of threat-relevant and threat-irrelevant animals were shown in Experiment 2. The emotional DPE was elicited in both experiments. In Experiment 1, the emotional DPE was significant in visual search for an angry face among neutral faces, but this effect was eliminated when these faces were inverted, suggesting that the DPE was due to the emotional category of the faces. In addition, the DPE was not significant in visual search for a neutral face (among angry or happy ones) or for a happy face among neutral distractors, suggesting the asymmetry of the emotional DPE. By contrast, the results of Experiment 2 revealed reliable DPEs in visual search for a fearful animal among peaceful animals. Taken together, the results of this study suggest that the valence of emotional stimuli can be remembered by the attention system to guide attention. Specifically, experience with negative stimuli can be remembered to guide attention to elicit a reliable DPE. Future research is called to test the influence of the observer’s emotional state on the DPE.

Key words: visual search, emotion, attention inhibition, inter-trial effect, Distractor Previewing Effect