Although faces are often included in the broad category of emotional visual stimuli, the affectiveimpact of different facial expressions is not well documented. The present experiment investigatedstartle electromyographic responses to pictures of neutral, happy, angry, and fearful facialexpressions, with a frontal face direction (directed) and at a 45 angle to the left (averted).Results showed that emotional facial expressions interact with face direction to produce startlepotentiation: Greater responses were found for angry expressions, compared with fear andneutrality, with directed faces. When faces were averted, fear and neutrality produced largerresponses compared with anger and happiness. These results are in line with the notion thatstartle is potentiated to stimuli signaling threat. That is, a forward directed angry face may signal athreat toward the observer, and a fearful face directed to the side may signal a possible threat inthe environment.
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