Table 1. The presentation of cues that were conditioned to opioid withdrawal was sufficient to produce somatic and subjective signs of opioid withdrawal in men who were maintained on methadone for OUD.

UR, unconditioned response. Modified from (7), with permission.

Variable	Unconditioned response	Conditioned response
Respiration	Increase	Increase
Skin temperature	Decrease	Decrease
Heart rate	Increase	Increase
Motor responses	Increase	Increase
Pupil diameter	Increase	Changes (nonsignificant)
Subjective reaction	Simulates opioid withdrawal	Indistinguishable from UR at this dose (0.1 mg)