Consciousness remains a mysterious topic which receives massive attention from
psychologists, philosophers and neuroscientists. Despite the long research tradition, the
function of consciousness remains unclear. One way to investigate which processes critically
require consciousness, is to compare conscious versus unconscious processing. A promising
domain to implement this approach is cognitive control. Cognitive control entails our abilities
to plan a new strategy, evaluate it, control its execution, and correct possible errors. This has
often been exclusively associated with consciousness, although recent data suggest otherwise.
Cognitive control therefore provides a fruitful domain to explore this debated issue. Two
types of cognitive control can be distinguished. Reactive control occurs in direct response to
an encountered problem or error, whereas proactive control entails planning ahead of possible
problems. In the current project, we first, and for the first time, rigorously test at the
behavioral level whether unconscious reactive control is possible and contrast it to conscious
reactive control. Second, we examine whether proactive control is also possible at an
unconscious level. Third, we investigate the neural correlates of reactive and proactive control,
again making sure we clearly distinguish conscious from unconscious trials.