Developing a self-reflective mind: infants' error-detection at 12 months predicts self-awareness at 18 months

Self-reflection is central to human cognition and has been proposed as one of the key drivers of our progress as a species, yet the development of self-reflective capacities is unknown. Using a novel gaze-contingent match-to-sample paradigm with concurrent eye-tracking and EEG recordings, we find evidence of self-reflective capacities in 12-month-old infants: they exhibit a neural response signature of error-tracking (the error-related negativity, ERN) when they make incorrect as opposed to correct choices and before receiving any feedback. Remarkably, the magnitude of the ERN at 12 months developmentally predicted the emergence of conceptual self-representation (mirror-self-recognition) in the same infants six months later. This relationship was specific to internal error-monitoring and not to external feedback processing, and could not be explained by infants age or general cognitive development. Moreover, infants did not simply detect their errors: the group of infants who passed the mirror test at 18 months (S) also adapted their behaviour post-error at 12 months. Following mistakes, S infants slowed their decisions and increased their visual exploration, demonstrating not only rudimentary metacognitive monitoring but also metacognitive control at 1 year of age. These findings provide the first empirical evidence that self-awareness may be rooted in earlier self-monitoring abilities, and reveal how a self-reflective mind can emerge from implicit cognitive monitoring mechanisms within the first years of life.