Why does the spectral tilt manifest during successful cognition and perception? A common thread through all studies is an association with increased attention, effort, or task engagement in conditions where the tilt emerges -- whether it be successful memory encoding, audiovisual processing, or arithmetic. The meaning of “attention” or “effort” can be difficult to define, and these processes blur together with the nature of the task at hand. For the sake of this review, we will define “attention” as an upregulation of mechanisms which downweigh noisy inputs and upweight inputs with high task relevance. Indeed, it has previously been suggested that decreases in low-frequency power facilitate increases in neural coding capacity, by decreasing synchronized unit activity, or increasing firing rates, and thereby increasing represented information content [45,52,74].
