A leaky evidence accumulation process for perceptual experience

The neural correlates supporting our perceptual experience of the world remain largely unknown. Recent studies have shown how stimulus detection and related confidence involve evidence accumulation (EA) processes similar to those involved in perceptual decision-making. Here, we propose that independently from any tasks, percepts are not static but fade in and out of consciousness according to the dynamics of a leaky evidence accumulation process (LEAP), and that confidence corresponds to the maximal evidence accumulated by this process. We discuss the implications and limitations of our proposal, assess how it may qualify as a neural correlate of consciousness, and illustrate how it brings us closer to a mechanistic understanding of phenomenal aspects of perceptual experience like intensity and duration, beyond mere detection. Evidence accumulation enables accurate perceptual decisions based on noisy sensory evidence. Here, we explore how leaky evidence accumulation processes (LEAPs) could determine perceptual consciousness.We propose that a stimulus fades in and out of consciousness according to the dynamics of the corresponding accumulated evidence. A percept is held to become conscious when accumulated evidence exceeds a threshold, increases in intensity until maximal evidence is reached, and ceases to be conscious when accumulated evidence drops below threshold due to a leaky accumulation regime.We account for perceptual monitoring by proposing a proxy for perceptual reliability: confidence in having perceived or not a stimulus is defined as the distance between the maximum of accumulated evidence and the detection threshold, thereby enabling metacognition for conscious and unconscious percepts.