Eye Movements during Emotional Scene Processing: Exploring the Role of Visual Perception in Intrusive Mental Imagery

摘要

Persistent re-experiencing of involuntary mental images is a hallmark characteristic of several psychopathological disorders, including posttraumatic stress disorder, obsessive compulsive disorder, depression, and schizophrenia. This study uses the established link between eye movements and visual processes to investigate healthy cognitive processes during both perceptual search and mental recreation of negative valence, high arousal scenes. Non-clinical subjects, with no history of mental illness or previous trauma, viewed 40 photographic scenes selected from the International Affective Picture System (IAPS). Stimuli chosen for this experiment were rated by the IAPS to have either negative valence with high arousal or neutral valence with low arousal. An infrared eye tracker recorded spontaneous eye movements while 20 scenes from each emotional category were presented in blocks of 5 on a digital monitor. Scene presentations (5 s) were preceded by a fixation cross (6 s) and followed by a pleasantness rating prompt (1-5). After a brief fixation period (12 s), participants were prompted to imagine the preceding scene on a blank gray screen (5 s), followed by a rating of imagery vividness (1-5). Average fixation count toward the central one half and outer one half of the image were compared across emotional and viewing/imagining task conditions. Results revealed a significantly greater amount of average fixations to peripheral over central areas of interest (AOIs) in both emotional conditions (p = 0.0132). However, the discrepancy in fixations directed toward central and peripheral regions was significantly greater during imagining of negative scenes (p .0001) than in any other condition. We hypothesize that this task-specific effect reflects cognitive processes underlying the formation of mental images which lend themselves to intrusive and involuntary re-experiencing. These results may be used to improve future behavioral interventions designed to reduce flashback symptoms in patients.