Unconscious reward cues increase invested effort, but do not change speed-accuracy tradeoffs

While both conscious and unconscious reward cues enhance effort to work on a task, previous research also suggests that conscious rewards may additionally affect speed-accuracy tradeoffs. Based on this idea, two experiments explored whether reward cues that are presented above (supraliminal) or below (subliminal) the threshold of conscious awareness affect such tradeoffs differently. In a speed-accuracy paradigm, participants had to solve an arithmetic problem to attain a supraliminally or subliminally presented high-value or low-value coin. Subliminal high (vs. low) rewards made participants more eager (i.e., faster, but equally accurate). In contrast, supraliminal high (vs. low) rewards caused participants to become more cautious (i.e., slower, but more accurate). However, the effects of supraliminal rewards mimicked those of subliminal rewards when the tendency to make speed-accuracy tradeoffs was reduced. These findings suggest that reward cues initially boost effort regardless of whether or not people are aware of them, but affect speed-accuracy tradeoffs only when the reward information is accessible to consciousness.