Stimulus awareness is necessary for both instrumental learning and instrumental responding to previously learned stimuli

Abstract

Instrumental conditioning is a crucial part of adaptive behaviour, allowing agents to selectively interact with stimuli in their environment to maximise benefit and minimise harm. Recently accumulating evidence suggests that instrumental conditioning, such as learning to approach/avoid, cannot proceed without conscious awareness of the stimuli. However, while unconscious instrumental conditioning may not be possible, whether accurate unconscious instrumental responding can emerge from consciously acquired knowledge of the stimulus-action-outcome contingencies is unknown. Here, we studied this question using instrumental trace conditioning, where participants learned to make approach/avoid decisions in response to reward- and punishment-predictive stimuli, in two within-subject modes: conscious (with the stimuli in plain view) and unconscious (visually masked). Both tasks were followed by an unconscious-only instrumental responding task. We show that even when the contingencies are reliably learned in the conscious mode, participants fail to act upon them instrumentally in the unconscious responding task. We also replicate the previous results that no instrumental learning occurs in the unconscious mode. Consequently, the absence of conscious awareness of the stimuli in the environment not only precludes instrumental conditioning, but also precludes any kind of instrumental responding to already known stimuli. This suggests that instrumental behaviour is entirely supported by conscious awareness of the world, and corroborates the proposals that consciousness may be necessary for adaptive behaviours requiring selective action.

Unconscious integration: Current evidence for integrative processing under subliminal conditions

“…Shanks et al (2021) recommend adjusting the stimulus presentation (durations) threshold individually for each participant to ensure subliminality (Beauny et al, 2020). However, for example as demonstrated by a series of rigorous studies from Skora and colleagues (Skora et al, 2021; Skora, Livermore, Nisini, & Scott, 2022; Skora & Scott, 2022), a large number of ‘aware’ trials/participants still needs to be removed after employing such procedure.…”

“…Skora, Livermore, Nisini, & Scott (2022) subsequently found differential cardiac responses towards reward/punishment feedback only in visible (but not subliminal) trials. Skora and Scott (2022) further showed that instrumental responding to subliminal cues is not possible even after learning with visible cues. Correa et al (2018), meanwhile, assessed IL with reversal learning components.…”

Can non-conscious knowledge support instrumental conditioning?

“…Rendering reward-and punishment-predictive stimuli subliminal (presented just under the threshold of conscious perception) through visual masking or continuous flash suppression appears to prevent the ability to learn the correct instrumental responses, in both delay and trace conditioning scenarios (Reber et al, 2018;Skora et al, 2021Skora et al, , 2022Skora et al, , 2023. What is more, even after the stimulus-action-outcome associations have been successfully learned consciously, subliminally presented stimuli fail to evoke the appropriate instrumental action to obtain reward or avoid punishments (Skora et al, 2024). Those results have been interpreted as consciousness facilitating higher-order processes, especially those requiring lasting and flexible adaptations, such as instrumental behaviour (Baars, 2002;Dehaene & Changeux, 2011;van Gaal et al, 2012;Skora et al, 2021).…”

“…To prevent explicit re-learning, participants won't receive feedback after every trial, but only a summation of gains and losses at the end of the phase (cf. Skora et al, 2024). We call this "the delayed instrumental responding phase".…”