TABLE 2. Trial Types and Frequencies Across Phases in a Study of Conditioned Fear in Panic Disorder^a.

		Conditioning and Generalization Stimuli

							CS+

	Phase	CS−	C1	C2	C3	C4	Coterminated With UCS	Did Not Coterminate With UCS	ITI
1	Preacquisition	6					0	6	6
2	Acquisition	12					9	3	12
3	Generalization test	12	12	12	12	12	6	6	12

CS−=conditioned safety cue; CS+=conditioned danger cue; C1, C2, C3, and C4=generalization stimulus classes 1, 2, 3, and 4; UCS=unconditioned stimulus; ITI=intertrial intervals, during which perceived risk or startle magnitudes were assessed. The shock reinforcement of the CS+ at the generalization test was included to avoid extinction of the conditioned response during the generalization sequence.

TABLE 2. Trial Types and Frequencies Across Phases in a Study of Conditioned Fear in Panic Disordera.

TABLE 2. Trial Types and Frequencies Across Phases in a Study of Conditioned Fear in Panic Disorder^a.