We evaluated the feasibility of recording multiple
physiological anxiety measures during a flight and how
well they could distinguish flight phobics from controls.
Benefits of baseline adjustment and transformation for
all variables and adjustment of heart rate by ventilation
to give additional heart rate were calculated. Effect size,
one measure of the power to discriminate groups, was between
1.1 and 1.7 for heart rate measures. Although respiratory
rate and minute ventilation, indicators of hyperventilation,
did not differ between groups, phobics paused more during
inspiration than did controls. Phobics also showed more
skin conductance fluctuations and less respiratory sinus
arrhythmia. Self-reported anxiety was a more powerful discriminator
than physiological measures, a result that may be partially
explained by how phobics were selected. These results indicate
that monitoring of multiple physiological systems outside
the laboratory is practical and informative. Physiological
measures of psychological importance can be quantified
accurately in a noisy, changing, unsupervised ambulatory
setting.