Affective flexibility without perceptual awareness

In an ever-changing environment, survival depends on learning which stimuli represent threat, and also on updating such associations when circumstances shift. Humans can acquire physiological responses to threat-associated stimuli even when they are unaware of them, but the role of awareness in updating threat contingencies remains unknown. This complex process - generating novel responses while simultaneously suppressing learned ones - relies on distinct neural mechanisms from initial learning, and has only been shown with awareness. Can it occur unconsciously? Here we show that it can. Participants underwent classical threat conditioning to visual stimuli that were suppressed from their awareness. One of two images was paired with an electric shock; halfway through the experiment, contingencies were reversed and the shock was paired with the other image. We found that physiological responses reflected changes in stimulus-threat pairings independently of stimulus awareness, demonstrating the sophistication of unconscious affective flexibility.