The processing of task-irrelevant emotion and colour in the Approach-Avoidance Task.

When processing information about human faces, we have to integrate different sources of information like skin colour and emotional expression. In 3 experiments, we investigated how these features are processed in a top-down manner when task instructions determine the relevance of features, and in a bottom-up manner when the stimulus features themselves determine process priority. In Experiment 1, participants learned to respond with approach-avoidance movements to faces that presented both emotion and colour features (e.g. happy faces printed in greyscale). For each participant, only one of these two features was task-relevant while the other one could be ignored. In contrast to our predictions, we found better learning of task-irrelevant colour when emotion was task-relevant than vice versa. Experiment 2 showed that the learning of task-irrelevant emotional information was improved in general when participants' awareness was increased by adding NoGo-trials. Experiment 3 replicated these results for faces and emotional words. We conclude that during the processing of faces, both bottom-up and top-down processes are involved, such that task instructions and feature characteristics play a role. Ecologically significant features like emotions are not necessarily processed with high priority. The findings are discussed in the light of theories of attention and cognitive biases.