Consciousness, Metacognition, & Perceptual Reality Monitoring Hakwan Lau1,2,3,4 [email protected] 1. Department of Psychology, University of California Los Angeles, USA 2. Brain Research Institute, University of California Los Angeles, USA 3. Department of Psychology, The University of Hong Kong, Hong Kong 4. State Key Laboratory of Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong I introduce an empirically-grounded version of a higher-order theory of conscious perception. Traditionally, theories of consciousness either focus on the global availability of conscious information, or take conscious phenomenology as a brute fact due to some biological or basic representational properties. Here I argue instead that the key to characterizing the consciousness lies in its connections to belief formation and epistemic justification on a subjective level1. An empirical link Neuroscience experiments have shown that, at least at the level of functional anatomy, the neural mechanisms for conscious perception and sensory metacognition are similar (Lau and Rosenthal 2011). By sensory metacognition we mean the monitoring of the quality or reliability of internal perceptual signals (Morales, Lau, and Fleming 2018). These two mechanisms both involve neural activity in the prefrontal and parietal cortices, outside of primary sensory regions. In terms of the cognitive mechanisms and behavior, there also seems to be some connection between the two. When people are asked to detect stimuli in the periphery, they are more likely to say that they see something (Knotts et al. 2018). This is true even when they are not actually more accurate in their decisions for the periphery compared to detection around fovea; they just make more false alarms in the periphery. One explanation is that we incorrectly represent the reliability of our internal perceptual signals, i.e. a failure of metacognition (Odegaard et al. 2018). Accordingly, we subjectively feel that we consciously see colorful details in the periphery, even though color sensitivity is poor in the periphery from as early as the retina. The ways that our conscious experience may be unrealistic (or inflated at times, Knotts et al. 2018), seem similar and related to the ways that our metacognition behaves (Miyoshi and Lau, forthcoming). These considerations have led some to think that consciousness and metacognition may be intrinsically related (Brown, Lau, and LeDoux, forthcoming). But it would be too strong to think they are one and the same; it is implausible that consciousness is necessary for any kind of sensory metacognition, as there may be unconscious mechanisms for perceptual monitoring too (Cortese, Lau, and Kawato, forthcoming). So what exactly is the relationship between consciousness and metacognition? Here I offer a theory of conscious perception to account for this link. 1 A short essay related to this article is published in Aeon Magazine: https://aeon.co/ideas/is- consciousness-a-battle-between-your-beliefs-and-perceptions 1 Some ‘magical’ intuitions Let us start with some intuitive examples. Intuitions are rarely universal. So they aren’t meant to be required assumptions for the arguments below. But they can sometimes help motivate ideas. On the internet there are videos2 showing that monkeys and apes seem capable of appreciating stage magic, i.e. tricks based on sleight of hand. Upon seeing these tricks, they express bewilderment and amusement, just like we do. Intuitively, it seems hard to imagine that the animals aren’t seeing the tricks consciously. To put it another way, I suggest there can never be such a thing as unconscious magic. It makes no sense for a stage magician to specialize in magic tricks that are registered unconsciously in the brains of the audience, but not consciously seen. Even if people giggle uncontrollably upon being presented with such unconscious tricks, this won’t be the same thing as genuine magic appreciation. The reason that stage magic, or at least some specific forms of it, may only work consciously probably has something to do with the very nature of conscious perception. Specifically, conscious seeing tends to lead to certain corresponding beliefs about what we see. There are three important features of these beliefs: i) they are actual personal-level beliefs, not just some representations in the brain unendorsed by the person as an agent; and yet ii) they tend to happen automatically, without having the subject engage in some effortful cognitive inference; iii) they feel subjectively justified, in the sense that it seems, from the agent’s point of view at least, very reasonable to believe them. These features are true only if the relevant seeing is conscious; unconscious sensing doesn’t give rise to beliefs with these features, if they give rise to beliefs at all. Together these features explain why seeing certain types of stage magic is so amusing. It is so because when you consciously see a magic trick, it tends to cause beliefs (e.g. a person’s turning into a cat) that conflict with other beliefs you have as a rational person (e.g. people don’t ever spontaneously turn into cats). Usually when you entertain such weird beliefs that are incompatible with everything else you believe, you reason your way out, so ultimately you may reject the weird beliefs. But here the beliefs occur automatically, beyond your volitional control. Also, they present themselves to you as justified, as if they are the most reasonable things to believe. That’s why it is so bewildering to see magic, and sometimes you can even see some of the same tricks over and over again without getting tired of them; all of this happens because of what conscious seeing constitutively involves. Contrast this with cognitively realizing something bizarre, such as that: today is Monday but yesterday you were at work, although you never work on Sundays. Upon having such weird realization, one would re-organize one’s thoughts, check it with other beliefs. If we see this unexpected situation happen over and over again, we would finally come to some resolution, such as accepting that we must have mistaken that today is Monday after all. But certain types 2 Such as: https://www.youtube.com/watch?v=FIxYCDbRGJc 2 of magic tricks, presented consciously to us, remain as visually entertaining as ever (when done properly), even when we fully expect to see something bewildering. There is something about conscious perception that seems to be epistemically stubborn, compared to other usual modes of acquiring evidence for reasoning and behavior. Consciousness as perceptual reality monitoring A certain version of a higher-order theory of conscious perception may account for the above three features. According to higher-order theories, having a (first-order) perceptual representation on its own is not sufficient for conscious perception. In addition, one would need to have a relevant higher-order representation. There is some debate among higher-order theorists regarding what should be the content and nature of the higher-order representation, leading to different versions of higher-order theories (Lau and Rosenthal 2011; Brown, Lau, and LeDoux, forthcoming). Here I propose that, given some necessary basic background functioning of an agent capable of perception and cognition (including some degree of rational decision-making and inference), conscious perception in that agent occurs if there is a relevant higher-order representation with the content that, a particular first-order perceptual representation is a reliable reflection of the external world right now. The occurrence of this higher-order representation gives rise to conscious experiences with the perceptual content represented by the relevant first-order state. The agent is typically not conscious of the content of this higher-order representation itself, but the representation is instantiated in the system in such a way to allow relevant inferences to be drawn (automatically) and to be made available to the agent (on a personal level, in ways that make the inferences feel subjectively justified). To understand why this may be a useful and plausible mechanism to have, let us run it through some key cases. These cases will also help illustrate why in the above paragraph I wrote “if” rather than “if and only if”; I specified one scenario in which conscious experience occurs but there’s also another scenario. According to the theory, blindsight occurs when a first-order representation occurs without the corresponding higher-order representation (see the below section on objections and replies for more details on this point). That’s why the perceptual capacity is there (due to the first-order representations), but the phenomenology of conscious perception is missing (Weiskrantz 1999). In visual working memory (e.g. holding an image ‘online’ in one’s mind for a few seconds), the corresponding early sensory (i.e. first-order) representations in the brain are activated during the memory delay (Harrison and Tong 2010). And yet, despite the activation of similar first-order representations, one does not mistakenly see the memorized image during the delay period, at least not in the normal way of consciously seeing, phenomenologically speaking. The content of working memory does not ‘leak out’ to the world. According to the theory, it is because the higher-order system (correctly) does not consider the relevant first-order representation to be reliable reflections of the state of the world right now. Instead the phenomenology (of imagery) is accounted for by the fact that the higher-order system considers the first-order representation to be a reliable internal representation generated by oneself. 3 Importantly, there are also cases when first-order representations occur without any conscious experience at all. For example, neurons in sensory areas show spontaneous activity. Literally, your cat-representing neurons are firing regularly now and then, on their own (Moutard, Dehaene, and Malach 2015). And yet you don’t have any sense of seeing or imagining a cat nearly as often.