Support for higher-order models of awareness

What is the computational architecture underlying consciousness and metacognition? One foundational question to ask in this domain is whether consciousness and metacognition are implemented by the same computational mechanisms responsible for first-order perceptual processing, or whether consciousness and metacognition are processed by downstream, higher-order computational mechanisms that are dissociable from the first-order mechanisms. My work provides converging evidence for the latter, higher-order view:

• Disruption of dorsolateral prefrontal cortex function by transcranial magnetic stimulation (TMS)* (Rounis et al., 2010) or concurrent task demands (Maniscalco & Lau, 2015) selectively impairs metacognition but not objective performance in perceptual tasks.
• Model comparison analysis applied to data in which task performance and ratings of awareness dissociate favors higher-order over first-order models of visual awareness (Maniscalco & Lau, 2016).
• Metacognition and task performance dissociate over time as one continuously performs a demanding task without rest, and this dissociation can be accounted for by individual differences in grey matter volume in anterior prefrontal cortex (Maniscalco et al., 2017).
• In a blindsight patient, frontoparietal areas in the brain are more activated for stimulus perception in the healthy visual field than in the blind visual field, even when task performance across the fields is equated (Persaud et al., 2011).

* One group recently reported being unable to replicate the TMS finding. However, they utilized experimental design and analysis choices that may have obscured their ability to find the effect, as detailed in Ruby, Maniscalco, & Peters 2018.

References

Rounis, E., Maniscalco, B., Rothwell, J. C., Passingham, R. E., Lau, H. (2010). Theta-burst transcranial magnetic stimulation to the prefrontal cortex impairs metacognitive visual awareness. Cognitive Neuroscience, 1(3), 165–175. https://doi.org/10.1080/17588921003632529

Maniscalco, B., Lau, H. (2015). Manipulation of working memory contents selectively impairs metacognitive sensitivity in a concurrent visual discrimination task. Neuroscience of Consciousness, 2015(1), niv002. https://doi.org/10.1093/nc/niv002

Maniscalco, B., & Lau, H. (2016). The signal processing architecture underlying subjective reports of sensory awareness. Neuroscience of Consciousness, 2016(1), 1–41. https://doi.org/10.1093/nc/niw002 [supplementary material]

Maniscalco, B., McCurdy, L. Y., Odegaard, B., Lau, H. (2017). Limited cognitive resources explain a tradeoff between perceptual and metacognitive vigilance. The Journal of Neuroscience, 37(5), 1213-1224. https://doi.org/10.1523/JNEUROSCI.2271-13.2016

Persaud, N., Davidson, M., Maniscalco, B., Mobbs, D., Passingham, R. E., Cowey, A., & Lau, H. (2011). Awareness-related activity in prefrontal and parietal cortices in blindsight reflects more than superior visual performance. NeuroImage, 58(2), 605–611. https://doi.org/10.1016/j.neuroimage.2011.06.081

Ruby, E., Maniscalco, B., & Peters, M. A. (2018). On a ‘failed’ attempt to manipulate visual metacognition with transcranial magnetic stimulation to prefrontal cortex. Consciousness and Cognition, 62, 34–41. https://doi.org/10.1016/j.concog.2018.04.009 [supplementary material]