I’m very pleased to announce our latest Mind & Language symposium on Matthias Michel and Jorge Morales’ forthcoming “Minority Reports: Consciousness and the Prefrontal Cortex.” Our outstanding commentators on the target article include Liz Irvine (Cardiff), Benjamin Kozuch (Alabama), and Michael Pitts with Kevin Ortego (Reed College).
A great deal of neuroscience research focuses on finding neural correlates of consciousness (NCCs), that is, neural states that are minimally sufficient for mental states to be conscious (Chalmers 2000). A number of neuroscientists and philosophers have maintained on the basis of experimental and theoretical evidence that prefrontal cortex is a NCC. Examples include the global workspace theory (Baars 2005, Dehaene & Changeux 2011) and the higher-order theory (Brown 2015, Lau & Rosenthal 2011, Lau & Brown 2019). Proponents of “back of the head” theories, in contrast, argue that consciousness primarily depends on neural activity in posterior parts of the cortex (Lamme 2006) or a “posterior hot-zone” (Koch et al. 2016, Koch 2018).
Numerous experiments, reviewed by Michel and Morales, provide evidence that conscious perception elicits increased activity in the PFC, while unconscious perception does not. Proponents of prefrontal theories take this to be evidence that PFC is part of the neural substrate of consciousness. Most of the experiments to which proponents of prefrontal theories appeal, however, make use of a “report-based” experimental method in which subjects are directed to report on whether they consciously perceive a stimulus or not. According to what Michel and Morales call the “argument from report,” this introduces a confound: the presence of neural activity in PFC that is correlated with conscious perception is also correlated with post-perceptual cognitive processes that enable verbal report. Hence, methods that require subjects to provide explicit reports of awareness (and unawareness) should be eliminated from analyses that search for the NCCs.
Michel and Morales defend prefrontal theories against the argument from report. In section 2 of the target article, they argue that in experiments comparing unconscious and conscious conditions, the observed difference in brain activity in the PFC is unlikely to be explained solely by its role in generating reports. “[T]here is little reason to believe,” they suggest, “that ‘seen’ and ‘unseen’ reports involve fundamentally different cognitive capacities.”
Proponents of the argument from report predict that in no-report experimental paradigms, differences in PFC activity between conscious and unconscious trials should be negligible. In section 3, Michel and Morales argue that this prediction conflicts with the best interpretation of the available evidence: there are differences in PFC activity between conscious and unconscious trials, they suggest, even when subjects do not have to provide reports.
Comments on this symposium will be open for at least a couple of weeks. Many thanks to Matthias, Jorge, and our three commentators for their stellar contributions! All of us here at the Brains Blog are also grateful to Gregory Currie, the other Mind & Language editors, and the staff at Wiley-Blackwell for their continued support of these symposia.
- You can learn more about Matthias Michel and his research here.
- You can learn more about Jorge Morales and his research here.
Below there are links to the authors’ video introduction, the target article, commentaries, and the authors’ replies.
1. Video Introduction by Matthias Michel and Jorge Morales:
2. Target Article: “Minority reports: Consciousness and the Prefrontal Cortex”
3. Commentaries and Replies:
- Liz Irvine,“Commentary on Minority Reports”
- Benjamin Kozuch, “Minority Retorts: Other Explanations for the Prefrontal Correlations”
- Michael Pitts with Kevin Ortego, “Why ‘No-Report’ Paradigms are an Important Tool for Consciousness Research”
- Matthias Michel and Jorge Morales, Replies