The Relationship between Pain and Emotional Faces: Investigating the Roles of Load and Valence

It is well established that pain perception can be decreased when one is completing a cognitive task or exposed to mood enhancing stimuli. However, there is much less research concerning valenced distractors. In this experiment, both stimulus valence and cognitive load were manipulated by presenting emotional faces that were either upright (low-load) or inverted (high-load). Participants viewed the images while experiencing noxious heat pulses and then gave ratings on both the visual and thermal stimuli. Pain intensity and unpleasantness were significantly higher when participants viewed happy faces compared with neutral faces, regardless of orientation. This finding is at odds with studies on emotional modulation of pain, in which pleasant stimuli reduce pain compared with neutral stimuli. However, as both upright and inverted happy faces were recognized with high accuracy, the present findings are in line with distraction studies in which concurrently presented low-load stimuli result in higher pain ratings than high-load distractors. That is, happy faces required much less processing for identification and were thus ineffective distractors compared with the more ambiguous neutral faces. Limitations and future directions are discussed.Master of Art