Feldner et al., 2003

Feldner, M. T., Zvolensky, M. J., Eifert, G. H., & Spira, A. P. (2003). Emotional avoidance: An experimental tests of individual differences and response suppression during biological challenge. Behaviour Research and Therapy, 41, 403-411.

Abstract
The present study examined the affective consequences of response inhibition during a state of anxietyrelated
physical stress. Forty-eight non-clinical participants were selected on the basis of pre-experimental
differences in emotional avoidance (high versus low) and subjected to four inhalations of 20% carbon
dioxide-enriched air. Half of the participants were instructed to inhibit the challenge-induced aversive
emotional state, whereas the other half was instructed to simply observe their emotional response. Participants
high in emotional avoidance compared to those low in emotional avoidance responded with greater
levels of anxiety and affective distress but not physiological arousal. Individuals high in emotional avoidance
also reported greater levels of anxiety relative to the low emotional avoidance group when suppressing
compared to observing bodily sensations. These findings are discussed in terms of the significance of
emotional avoidance processes during physical stress, with implications for better understanding the nature
of panic disorder.

The intervention protocol is included below quoted from Feldner (2003).