摘要：We investigated whether offset-control of the unconditioned stimulus (US) reduces context conditioning induced by US-unpredictability within a human conditioned suppression preparation. We also examined lack of control vs. loss of control. Three groups (No Controllability, NC; Controllability, C; Loss of Controllability, LC) received unsignaled USs during two learning phases (ACQ1-2). The NC group, never had offset-control, whereas the C group, always had offset-control. The LC group, had offset-control during ACQ1, but not during ACQ2. Results indicated that US-unpredictability led to contextual conditioned suppression during ACQ1, only when participants did not have offset-control; when they did, no context conditioning was established. From ACQ1 to ACQ2, contextual conditioned suppression increased in the LC group, but it was not more pronounced than in the NC group. These data suggest that offset-control attenuates context conditioning induced by US-unpredictability and – at least in this paradigm – loss of control is not worse than lack of control.
