Hyperventilation (HV) is often considered part of a defense
response, implying an unpleasant emotion (negative valence)
combined with a strong action tendency (high arousal). In this
study, we investigated the importance of arousal and valence
as triggers for HV responses. Forty women imagined eight different
scripts varying along the arousal and valence dimensions. The
scripts depicted relaxation, fear, depressive, action, and desire
situations. After each trial, the imagery was rated for valence,
arousal, and vividness. FetCO2, inspiratory and
expiratory time, tidal volume, and pulse rate were measured
in a nonintrusive way. FetCO2 drops and decreases
in inspiratory and expiratory time occurred in all but the
depressive and the relaxation scripts, suggesting that a defense
conceptualization of hyperventilation is not always appropriate.