What is your brain doing when you’re unaware of your actions?

In a groundbreaking study, researchers at Yale University explored the brain activity that occurs when individuals are unaware of their actions. Led by Professor Hal Blumenfeld, the study delved into the debate that has persisted for over 130 years, initially proposed by William James and Wilhelm Wundt. The investigation was inspired by the sliding block puzzle game Rush Hour, in which participants were asked to recall their last move and rate their confidence after the game paused.

Using electroencephalography (EEG) to measure brain activity of 67 participants, the researchers discovered distinct differences in brain signals between aware and unaware moves. Specifically, a motor-planning signal called pre-movement positivity was stronger during aware trials and a sensory processing signal called N140, associated with awareness of bodily sensation, was also enhanced.

Neither signal alone was sufficient to determine awareness. Furthermore, the study found a third factor that neither theorist had anticipated: as the participants became more bored and tired during the task, their pupil diameter shrank, indicating a decline in alertness and corresponding reduction in awareness. The findings suggest that consciousness is multifaceted and that unawareness may be a necessary feature for efficient daily functioning.

The study also suggests that unawareness of action could play a role in various conditions, such as epilepsy, Parkinson's disease, and schizophrenia, affecting diagnosis, rehabilitation, and legal questions of intent.