Attentive novelty detection in humans is governed by pre-attentive sensory memory

Abstract

BEING able to detect unusual, possibly dangerous events in the environment is a fundamental ability that helps ensure the survival of biological organisms^1–3. Novelty detection requires a memory system that models (builds neural representations of) events in the environment, so that changes are detected because they violate the predictions of the model. The earliest physiologically measurable brain response to novel auditory stimuli is the mismatch negativity⁴, MMN, a component of the event-related potential. It is elicited when a predictable series of unvarying stimuli is unex-pectedly followed by a deviating stimulus⁵. As the occurrence of MMN is not usually affected by the direction of attention^5–7, MMN reflects the operation of automatic sensory (echoic) memory⁸, the earliest memory system that builds traces of the acoustic environment against which new stimuli can be compared⁵. The dependence of attentive novelty detection on earlier, pre-atten-tive processes, however, has remained elusive. Previous, related studies^9–12 seem to suggest a relationship between MMN and atten-tive processes, although no conclusive evidence has so far been shown. Here we address novelty detection in humans both on a physiological and behavioural level, and show how attentive novelty detection is governed by a pre-attentive sensory memory mechanism.