Reliable evidence for implicit attentional responses to aversive conditioned stimuli

Literature on implicit Pavlovian conditioning has generated a long-standing debate, and evidence for implicit aversive learning effects has often been criticized for its lack of experimental rigor and statistical reliability. We set out to investigate whether attentional emotional responses to aversive conditioned stimuli can occur implicitly.Across two experiments, participants completed an aversive conditioning task in which abstract geometrical shapes were conditioned with high or low probabilities of hearing an aversive white noise. A novel Bayesian awareness categorization tool was applied to obtain evidence for participants who lacked stimulus-outcome contingency awareness. Then, conditioned stimuli were presented in an emotional attentional blink (Exp.1, n=40; n=21 unaware) and a modified flanker task (Exp.2, n=86; n= 69 unaware) to measure attentional conditioned effects. Finally, participants rated the subjective valence and arousal caused by the conditioned stimuli. We found that, for participants unaware of contingencies, conditioned stimuli associated with high probabilities of aversive noise were harder to detect in the emotional attentional blink and generated less attentional interference on the flanker task. Regarding the development of subjective responses, only aware participants showed learning effects. For both experiments, the awareness categorization did not lead to regression-to-the-mean effects, revealing a reliable determination of awareness states. These findings provide evidence for the existence of implicit aversive learning as demonstrated via conditioned attentional responses, and build an analytical framework that can be extrapolated to other implicit paradigms.