Infrequent panic: physiological and subjective reactions to hyperventilation.

Forty-eight females were evaluated to detect differences in panic-related symptomatology and physiological responses to 2 min of hyperventilation. Ss were divided into 3 groups: infrequent panickers; no panic/high trait anxiety; and no panic/low trait anxiety. The low trait anxiety group scored significantly lower on various self-report measures of anxiety-related symptomatology compared to Ss with infrequent panic and high trait anxiety. Hyperventilation produced no significant group differences in physiological reactivity or recovery. However, Ss with low trait anxiety reported significantly less severe sensations and a significantly lower incidence of panic during hyperventilation than the infrequent panickers and the high trait anxiety group. Ss who panicked during hyperventilation reported more intense sensations and negative cognitions than those who did not panic. Thus, Ss were distinguished by their subjective, but not their physiological responses.