Edinburgh Napier University

  In two experiments we measured the effects of 7.5% CO₂ inhalation on the interpretation of video footage recorded on closed circuit television (CCTV). As predicted, inhalation of 7.5% CO₂ was associated with increases in physiological and subjective correlates of anxiety compared with inhalation of medical air (placebo). Importantly, when in the 7.5% CO₂ condition, participants reported the increased presence of suspicious activity compared with placebo (Experiment 1), a finding that was replicated and extended (Experiment 2) with no concomitant increase in the reporting of the presence of positive activity. These findings support previous work on interpretative bias in anxiety but are novel in terms of how the anxiety was elicited, the nature of the interpretative bias, and the ecological validity of the task.