Consciousness Online -10 Years Later

It was way back in May of 2008 that I finally decided to try to organize an online consciousness conference. Ten years later and the conference material from the resulting five online conferences is for the most part still there. There is the inevitable link rot that creeps in and I try to keep up with it but in some cases it is unavoidable. The first conference was hit the hardest because back then I used google video which went under (and somehow I lost all of the videos I had there) and hosted papers and related material on a server I can’t access anymore (I also let the custom url lapse a while back and it is now the original A lot survives, though, and I have been glad to see people linking to it in their courses and some of the discussion (all of which is still there) has been cited in scholarly papers!

I actually had the idea for a consciousness-specific online conference in the summer of 2007, and bothered a few people about trying to get something like this going over the next year or so (I vaguely remember pitching the idea of a Kripke & Consciousness online conference to the early Kripke Center in 2007).  My experience at the Tucson consciousness conference in April of 2008 finally goaded me to act. I had just recently started blogging (happy 11th birthday to this blog by the way!) and seen the Online Philosophy Conference so I thought that was an ideal format (but with more video). People warned me that it was too much work and that the previous online philosophy conferences had not really succeeded. I thought if it was kept small it could be done, and since I was tired of waiting for someone else to do it, I set out to do it myself. I spent the summer getting ready,  announced the conference in August of 2008 and held the conference in February of 2009 (papers published in April of 2010)…a lot of work but also a lot of fun!

I organized the last one in 2013 and the final special issue I edited as a result of that came out in 2015. All in all that is seven years I invested into that project! It was a shame that I had to stop because I really enjoyed working on it and was trying to grow it into something but as I was coming up for tenure it was communicated to me that my scholarly work was excellent and that I needed to focus on contributing something to the college. In other words, another conference, and another publication was not going to help me get tenure (this is how I interpreted it anyway). So I turned my focus to organizing things at LaGuardia and I just could not do both with my teaching load (5/4 plus extra classes). I was awarded tenure in the fall of 2015 and I briefly thought about trying to revive it but by then I had kids! Plus, I have been happy to see the Brains Blog, and their Minds Online Conference (and now Neural Mechanisms Online) spring up to fill the void (by the way, here is the excellent special session for CO5 organized by John Schwenkler).

One thing I have learned is that it is possible for one person/a small group of people to make an impact but what we really need is to ‘institutionalize’ online conferences, by which I mean have them sponsored by professional organizations like the APA or the Association for the Scientific Study of Consciousness  (or the Tucson Center for Consciousness Studies, etc) but it is not clear how to do that without money entering the picture (I footed the small bill for any costs related to running Consciousness Online and everyone else worked for free!).

The thing I am most proud of is that the conferences all resulted in publications (4 journal issues and one book). My basic idea was to have the conference itself count as part of the review process. The papers were usually rewritten after discussion and then sent out for a more traditional review before finally being published (and so the result was not just a conference proceedings but a new paper sharpened by the conference (remember I was still an idealistic graduate student at the time!)). I was very lucky to have the general editor from the Journal of Consciousness Studies initially approach me about editing a special issue and I ran with it from there. A quick check of Google Scholar shows that the six resulting papers from the first conference have (mostly) done pretty well since being published in 2010.

Prefrontal Cortex, Consciousness, and…the Central Sulcus?

The question of whether the prefrontal cortex (PFC) is crucially involved in conscious experience is one that I have been interested in for quite a while. The issue has flared up again recently, especially with the defenders of the Integrated Information Theory of Consciousness defending an anti-PFC account of consciousness (as in Christof Koch’s piece in Nature). I have talked about IIT before (here, here, and here) and I won’t revisit it but I did want to address one issue in Koch’s recent piece. He says,

A second source of insights are neurological patients from the first half of the 20th century. Surgeons sometimes had to excise a large belt of prefrontal cortex to remove tumors or to ameliorate epileptic seizures. What is remarkable is how unremarkable these patients appeared. The loss of a portion of the frontal lobe did have certain deleterious effects: the patients developed a lack of inhibition of inappropriate emotions or actions, motor deficits, or uncontrollable repetition of specific action or words. Following the operation, however, their personality and IQ improved, and they went on to live for many more years, with no evidence that the drastic removal of frontal tissue significantly affected their conscious experience. Conversely, removal of even small regions of the posterior cortex, where the hot zone resides, can lead to a loss of entire classes of conscious content: patients are unable to recognize faces or to see motion, color or space.

So it appears that the sights, sounds and other sensations of life as we experience it are generated by regions within the posterior cortex. As far as we can tell, almost all conscious experiences have their origin there. What is the crucial difference between these posterior regions and much of the prefrontal cortex, which does not directly contribute to subjective content?

The assertion that loss of the prefrontal cortex does not affect conscious experience is one that is often leveled at theories that invoke activity in the prefrontal cortex as a crucial element of conscious experience (like the Global Workspace Theory and the higher-order theory of consciousness in its neuronal interpretation by Hakwan Lau and Joe LeDoux (which I am happy to have helped out a bit in developing)). But this is a misnomer or at least is subject to important empirical objections. Koch does not say which cases he has in mind (and he does not include any references in the Nature paper) but we can get some ideas from a recent exchange in the Journal of Neuroscience.

One case in particular is often cited as evidence that consciousness survives extensive damage to the frontal lobe. In their recent paper Odegaard, Knight, and Lau have argued that this is incorrect. Below is figure 1 from their paper.

Figure 1a from Odegaard, Knight, and Lau

This is brain of Patient A, who was reportedly the first patient to undergo bi-lateral frontal lobectomy.  In it the central sulcus is labeled in red along with Brodman’s areas 4, 6, 9, and 46. Labled in this way it is clear that there is an extensive amount of (the right) prefrontal cortex that is intact (basically everything anterior to area 6 would be preserved PFC). If that were the case then this would hardly be a complete bi-lateral lobectomy! There is more than enough preserved PFC to account for the preserved conscious experience of Patient A.

Boly et al have a companion piece in the journal of neuroscience and a response to the Odegaard paper (Odegaard et al responded to Boly as well and made these same points). Below is figure R1C from the response by Boly et al.

Figure R1C from response by Melanie Boly, Marcello Massimini, Naotsugu Tsuchiya, Bradley R. Postle, Christof Koch, and Giulio Tononi

Close attention to figure R1C shows that Boly et al have placed the central sulcus in a different location than Odegaard et al did. In the Odegaard et al paper they mark the central sulcus behind where the 3,1,2 white numbers occur in the Boly et al image. If Boly et al were correct then, as they assert, pretty much the entire prefrontal cortex is removed in the case of patient A, and if that is the case then of course there is strong evidence that there can be conscious experience in the absence of prefrontal activity.

So here we have some experts in neuroscience, among them Robert T. Knight and Christof Koch, disagreeing about the location of the central sulcus in the Journal of Neuroscience –As someone who cares about neuroscience and consciousness (and has to teach it to undergraduates) this is distressing! And as someone who is not an expert on neurophysiology I tend to go with Knight (surprised? he is on my side, after all!) but even if you are not convinced you should at least be convinced of one thing: it is not clear that there is evidence from “neurological patients in the first half of the 20th century” which suggests that the prefrontal cortex is not crucially involved in conscious experience. What is clear is that is seems a bit odd to keep insisting that there is while ignoring the empirical arguments of experts in the field.

On a different note, I thought it was interesting that Koch made this point.

IIT also predicts that a sophisticated simulation of a human brain running on a digital computer cannot be conscious—even if it can speak in a manner indistinguishable from a human being. Just as simulating the massive gravitational attraction of a black hole does not actually deform spacetime around the computer implementing the astrophysical code, programming for consciousness will never create a conscious computer. Consciousness cannot be computed: it must be built into the structure of the system.

This is a topic for another day but I would have thought you could have integrated information in a simulated system.

Mary, Subliminal Priming, and Phenomenological Overflow

Consider Mary, the super-scientist of Knowledge Argument fame. She has never seen red and yet knows everything there is to know about the physical nature of red and the brain processing related to color experience. Now, as a twist, suppose we show her red subliminally (say with backward masking or something). She sees a red fire hydrant and yet denies that she saw anything except the mask (say). Yet we can say that she is primed from this exposure (say quicker to identify a fire truck than a duck subsequently or something). Does she learn what it is like to see red from this? Does she know what it is like to see red and yet not know that she knows this?

It seems to me that views which accept phenomenological overflow, and allow that there is phenomenal consciousness in the absence of any kind of cognitive access, have to say that the subliminal exposure to red does let Mary learn what it is like for her to see red (without her knowing that she has learned this). But this seems very odd to me and thus seems to me that this is a kind of a priori consideration that suggests there is no overflow.

Of course I have had about 8 hours of sleep in the last week so maybe I am missing something?


Gottlieb and D’Aloisio-Montilla on Brown on Phenomenological Overflow

Last year I started to try to take note of papers that engage with my work in some way (previous posts here, here, here, here, here, here, and here). The hope was to get some thoughts down as a reference point for future paper writing. So far not much in that department has been happening; with a 3 year old and a 1 month old it is tough to find time to write (understatement!) but I am hoping I can “normalize” my schedule in the next few weeks and try to get some projects off of the back burner. At any rate I have belatedly noticed a couple of papers that came out and thought I woud quickly jot down some notes.

The first paper is one by Joseph Gottlieb and came out in Philosophical Studies in October of 2017. It is called The Collapse Argument and makes the argument that all of the currently available mentalistic first-order theories of consciousness turn out to really be versions of the higher-order theory of consciousness. I don’t know Joseph IRL (haha) but we have emailed about his papers several times, though I usually get back him too late for it to matter on account of the 16 classes a year I have been teaching since 2015 (for anyone who cares: I am contractually obligated to teach 9 a year and  in addition I teach another 7 as an adjunct (the maximum allowed by my contract)…sadly this is what is required in order for my family to live in New York! ) and I have blogged about his work here before (linked to above) but I really, really like this paper of his. First, I obviously agree with his conclusion and it is nice to see some discussion of this issue. I took some loose steps in this direction myself in the talk I gave at the Graduate Center’s Cognitive Science Speaker Series back in 2015. I thought about writing it up but then had my first son and then found out about Joseph’s paper, which is better than what I could have come up with anyway! I suppose the only place we might disagree is that I think this applies to Block’s first-order theory as well.

But even though I really like the paper there is a bit I would quibble about (but not very much). Gottlieb seems to take seriously my argument that higher-order theories are in principle compatible with phenomenological overflow but I am not sure I agree with how he puts it. He says,

As Richard Brown (2014) points out, HO theorists don’t need to claim that we are aware of our conscious states in all their respects. I might be aware that I am seeing letters (a fairly generic property) but not the identity of every letter I am seeing. In other words, I can be unaware of some of the information represented by the first- order state without the state itself being unconscious (ibid). What happens, then, is: I am phenomenally conscious of the entire 3 X  4 array, with representations of the identities of all the letters available prior to cuing. But only a small number (usually around four) ever get through, accessed by working memory. That’s overflow, and perfectly consistent with HO theory.

In the paper he is citing I was trying to make the point that the higher-order theories which deny overflow do not thereby also commit themselves to the existence of unconscious *states* which are doing heavy lifting. If the states are targeted by the appropriate higher-order representation then those states are conscious. Yet one may not represent all of the properties of the state and so, even though the state is conscious, there is information encoded in the state which you are not aware of (and so is unconscious). That unconscious information (that is to say, that aspect of the conscious state)  is (presumably) what you come to be aware of when you get the cue in the relevant experiments. So it is a bit strange to see this part of the paper cited as supporting overflow (though I do think the position is compatible with overflow I wasn’t thinking of it in this way). But I think I see his point. On the higher-order view it will true to say that one has a phenomenally conscious experience of all of the letters and the details but only access a few (even though what it is like for one may not have all of the details, which is really what I think the overflow people mean to be saying).

This point, though, is I think they key difference between higher-order theories and Global Workspace theories (which is what Block is really targeting with his argument). The basic idea behind the higher-order approach is this. When one is presented with the stimulus all or most of the details of the stimulus are encoded in first-order visual states (that is, states which represent the details of the visual scene). Let’s call the sum-total representational state S. S represents all (or most) of the letters and their specific identifies. One can have S without being aware that one is in S. In this case S is unconscious. Now suppose that one comes to have a (suitable) higher-order awareness that one is in S. According to the higher-order theory of consciousness one thereby comes to have a phenomenally conscious experience of S and becomes consciously aware of what S represents. But since one’s higher-order awareness is (on the theory) a cognitive thought-like state, it will describe its target. Thus one can be aware of S in different ways. Suppose that one is aware of S merely as a clock-like formation of rectangles. Then what it is like for one will be like seeing a clock-like formation of rectangles. Being aware of S seems to keep S online and as one is cued one may come to have a different higher-order awareness of S. One may become aware of some of the details already encoded in S. One was already aware of them, in a generic way, but now one comes to be aware of the same details but just in more detail. Put more in terms of the higher-order theory, one’s higher-order thought(s) come to have a different content than they previously did. The first higher-order state represented you as merely seeing a bunch of rectangles and now you have a state that represents you as seeing a bunch of rectangles where the five-o’clock position is occupied by a horizontal bar (or whatever). Notice that in this way of thinking about the case there are no unconscious states (except the higher-order ones). S is conscious throughout (just in different respects) and it will be true that subjects consciously see all of the letters (just not all of the details).

I want to keep this in mind as I turn to the second paper but before we do I also like Gottlieb’s paper because it actually references this blog! I think this may be the first time my personal blog has been cited in a philosophy journal! I will have more to say about that at some point but for now: cool!

The second paper is by Nicholas D’Aloisio-Montilla and came out in Ratio in December 2017. It is called A Brief Argument for Consciousness without Access. This paper is very interesting and I am glad I became aware of it and D’Alosio-Montilla’s work in general. He is trying to develop a case for phenomenological overflow based on empirical work on aphantasics. These are people who report lack of the ability to form mental imagery. I have to admit that I think of myself this way (with the exception of auditory imagery) so I find this very interesting. But at any rate the basic point seems to be that there is no correlation between one’s ability to form mental imagery (as measured in various ways) and one’s ability to perform the Sperling-like tasks under discussion in the overflow debate.  His basic argument is that if you deny phenomenological overflow then you must think that unconscious representations are the basis of subject’s abilities. Further, if that is the case then it must be because subjects form a (delayed) mental image of the original (unconscious) representation. But there is evidence that subject’s don’t form mental images and so evidence that we should not deny overflow.

I disagree with the conclusion but it is nice to see this very interesting argument and I hope it gets some attention. Even so, I think there is some mis-characterization of my view related to what we have just been talking about in Gottlieb’s paper. D’Alosio-Montilla begins by setting the problem up in the following way,

The reports of subjects [in Sperling-like tasks] imply that their phenomenology (i.e. conscious experience) of the grid is rich enough to include the identities of letters that are not reported (Block, 2011, p.1; Land- man et al., 2003; cf. Phillips, 2011b). As Sperling (1960, p.1) notes, they ‘enigmatically insist that they have seen more than they can … report afterwards’. Introspection therefore suggests that subjects consciously perceive almost all 12 items of the grid, even if they are limited to accessing the contents of just one row (Block 2011; Carruthers, 2015). The ‘overflow’ argument uses this phenomenon as evidence in favor of the claim that the capacity of consciousness outstrips that of access. Overflow theorists maintain that almost all items of the grid are consciously represented by perceptual and iconic representations (D’Aloisio-Montilla, 2017; Block, 1995, 2007, 2011, 2014; Bronfman et al., 2014; for further discussion, see Burge, 2007; Dretske, 2006; Tye, 2006).

This is a nice statement of the overflow argument and the claim that it is the specific identifies of the items of the grid which are consciously experienced but this way of framing the argument begs the question against the higher-order interpretation. The reports in question do not imply rich phenomenology because, as we have just discussed, subjects are correct that they have consciously seen all of the letters even if they are wrong that they consciously experienced the details. Because of this the higher-order no-overflow theorist can accept that there is no correlation between mental imagery ability and Sperling-like task performance and for pretty much the same reasons that the first-order theorist does: because there is a persisting conscious experience.

D’Aloisio-Montilla then goes on to give two objections to his interpretation of my account. He puts it this way,

A final way out for the no-overflow theorist might be to allow for a limited phenomenology of the cued item to occur without visual imagery (Brown, 2012, 2014; Carruthers, 2015). Brown (2012, p. 3) suggests that subjects can form a ‘generic’ experience of the memory array’s items while the array is visible, since attention can be thinly distributed to bring fragments of almost all items to both phenomenal and access consciousness. Phenomenology, for example, might include the fact that ‘there is a formation of rectangles in front of me’ without specifying the orientation of each rectangle (Block, 2014). However, there a still number of problems with an appeal to generic phenomenology. First, subjects report no shift in the precision of their conscious experience when they are cued to a subset of items that they subsequently access (Block, 2007; Block, 2011).

First, I would point out that my goal has always been to show that the higher-order theory of consciousness is both a.) compatible with the existence of overflow but also b.) compatible with no-overflow views and gives a different account of this than Global Workspace Theories (or other working memory-based views). So I am not necessarily a ‘no-overflow theorist’ though I am someone who thinks that i.) overflow has not been established but assumed to exist and ii.) even if there is overflow it is mostly an argument against a particular version of the Global Workspace theory of consciousness, not generally against cognitive theories of consciousness.

But ok, what about his actual argument? I hope it is clear from what we have said above that one would not expect subjects to report ‘a shift in precision’ of their phenomenology. One has a conscious experience (generic or vague in certain respects) but in so doing you help to maintain the first-order (detailed) state. When you get the cue you focus on the aspect of the state which you had only generically been aware of (by coming to have a higher-order awareness with a different content) but what it is like for you is just like feeling like you see all of the details and then focusing in on some of the details. No change in precision. But even so these appeals to the subject’s reports are all a bit suspect.  I use the Sperling stimulus in my classes every semester as a demo of iconic memory and an illustration of how philosophical issues connect to empirical ones and my students seem to be mixed on whether they think they “see all of the letters”. Granted we only do 10-20 trials in the classroom and not in the lab (in Sperling they did thousands of trials) and these are super informal reports made orally in the classroom…but I still think there is a issue here. I have long wanted there to be some experimental philosophy done on this question. It would be nice to see someone replicate Sperling’s results but also include some qualitative comments from subjects about their experience. I almost tried to get this going with Wesley Buckwalter years ago but it didn’t go through. I still think someone should do this and that the results would be useful in this debate.

D’Aloisio-Montilla goes on to say,

Second, subjects are still capable of generating a ‘specific’ image – that is, a visual image with specific content – when the cue is presented. Assuming that the cued item is generically conscious on the cue’s onset, imagery would necessarily be implicated in maintaining any persisting consciousness of the cued item (whether gist-like or specific) throughout the blank interval. Thus, we can still expect to see a correlation between imagery abilities and task performance, because subjects can generate either (1) a visual image with specific phenomenology, or (2) a visual image with generic phenomenology (Phillips, 2011a; Brown, 2014). In any case, subjects who generate a specific phenomenology of the cued item should perform better than those who rely solely on a gist-like experience, and so Brown’s interpretation is also called into question.

But again this seems to miss the point of the kind of no-overflow account the higher-order thought theory of consciousness delivers. It is not committed to mental imagery as a solution. Subjects have a persisting conscious experience which may be less detailed than they experience it as.

Shesh that is a lot and I am sure there is a lot more to say about it but nap time is over and I have to go and play Dinosaur now.

Papa don’t Teach (again!)


The Brown Boys

2018 is off to an eventful start in the Brown household. My wife and I have just welcomed our newborn son Caden (pictured with older brother Ryland and myself to the right) and I will soon be going on Parental Leave until the end of April. Because of various reasons I had to finish the last two weeks of the short Winter semester after Caden was born (difficult!). That is all wrapped up now and there is just one thing left to do before officially clocking out.

Today I will be co-teaching a class with Joseph LeDoux at NYU. Joe is teaching a course on The Emotional Brain and he asked me to come in to discuss issues related to our recent paper. I initially recorded the below presentation to get a feel for how long the presentation was (I went a bit overboard I think) but I figured once it was done I would post it. The animations didn’t work out (I used powerpoint instead of Keynote), I lost some of the pictures, and I was heavily rushed and sleep-deprived (plus I seem to be talking very slow when I listen back to it) but at any rate any feedback is appreciated. Since this was to be presented to a neuroscience class I tried to emphasize some of the points made recently by Hakwan Lau at his blog.

Fanselow and Pennington on LeDoux and Colleagues

Things have been really hectic around here lately and I have been meaning to post something on this for a while now.

Recently Michael Fanselow and  Zachery Pennington, both at UCLA, have argued against the kind of position developed by LeDoux and Colleagues. This includes LeDoux’s paper with Daniel Pine who is a psychiatrist, his paper with me developing a higher-order theory of fear and anxiety, and his paper with Stefan Hofmann who is a cognitive behavioral therapist. The papers are linked to below.

LeDoux and Pine responded here:

There is also a a bit of a response in our recent general piece on these issues here:

I think the responses do a good job but there is one passage that I think needs more attention.

This is from the ‘Psychiatric Dark Ages’ paper where Fanselow and Pennington say,

5. A logical inconsistency within the two-system framework

The two-system framework formally states that fear as a subjective experience arises from the neural circuitry that gives rise to working memory and conscious recollection, and more specifically, to episodic memory (LeDoux & Brown, 2017; LeDoux, 2017). As an example of an episodic memory, I can recall the what, where and when of yesterday’s breakfast. This includes my memory for the flavors I experienced. I can use this memory to flexibly guide today’s choices—yesterday I had bacon, better stick to oatmeal today. The neural circuits that support such episodic memories are also the neural systems that allow animals to take alternate paths when the one normally used is blocked. And in the two-systems framework, they support the subjective emotion of fear. The question then becomes what is unique about fear that differentiates it from other cognitions? The answer to this question is immediately apparent if one looks at LeDoux and colleagues’ schematics [Figure 1b (LeDoux & Pine, 2016), Figure 2a (LeDoux, 2017) and Figure 5 (LeDoux & Brown, 2017)]: it is the input from the subcortical defensive system, and in the case of LeDoux and Brown, feedback from the behavioral responses generated by the subcortical defensive circuits. In other words, the unique qualities of subjective fear in the two-system framework reduce to the more parsimonious single generator model, where conscious fear reflects one component of an integrated response. Indeed, the additional machinery needed to generate subjective report probably adds additional noise, rendering it, as many previous to us have suggested, a less pure and objective measure of fear.

The central argument here seems to be that since we allow that activity of the amygdala and other lower-order areas influence the subjective experience of fear then it is the case that you could have had that same subjective experience without the higher-order activity. This simply doesn’t follow.

On the view LeDoux and I developed the unique qualities of subjective fear come from the unique contents of certain higher-order representations. It is entirely plausible that activity from the subcortical defensive system may cause the appropriate higher-order representations to have a specific kind of content, which in turn results in a specific subjective experience. When that activity is missing and fear is still felt it may be subjectively different because of the missing causal contribution from the subcortical defensive circuit. This does not collapse the view into a first-order view.

What the HOROR view is committed to, though, is that if it were to be the case that we could, via some other means than normal, mimic the causal input of the subcortical circuits, then we could produce the higher-order state with the appropriate content without any activity in the defensive survival circuits and that would result in the exact same subjective experience of fear.


Ian Phillips on Simple Seeing

A couple of weeks ago I attended Ian Phillips’ CogSci talk at CUNY. Things have been hectic but I wanted to get down a couple of notes before I forget.

He began by reviewing change blindness and inattentional blindness. In both of these phenomena subjects sometimes fail to recognize (or report) changes that occur right in front of their faces. These cases can be interpreted in two distinct ways. On one interpretation one is conscious only of what what is able to report on, or attend to. So if there is a doorway in the background that is flicking in and out of existence as one searches the two pictures looking for a difference and when one is asked one says that they see no difference between the two pictures one does not consciously experience the door way or its absence. This is often dubbed the ‘sparse’ view and it is interpreted as the claim that conscious perception contains a lot less detail in it than we naively assume.

Fred Dretske was a well known defender of a view on which distinguishes two components of seeing. There is what he called ‘epistemic seeing’ which, when a subject sees that p, “ascribes visually based knowledge (and so a belief) to [the subject]”. This was opposed to ‘simple seeing’ which “requires no knowledge or belief about the object seen” (all quoted material is from Phillips’ handout). This ‘simple seeing’ is phenomenally conscious but the subject fails to know that they have that conscious experience.

This debate is well known and been around for a while. In the form I am familiar with it it is a debate between first-order and higher-order theories of consciousness. If one is able to have a phenomenally conscious experience in the absence of any kind of belief about that state then the higher-order thought theory on which consciousness requires a kind of higher-order cognitive state about the first-order state for conscious perception to occur, is false. The response developed by Rosenthal, and that I find pretty plausible, is that in change blindness cases the subject may be consciously experiencing the changing element but not conceptualize it as the thing which is changing. This, to me, is just a higher-order version of the kinds of claims that Dretske is making, which is to say that this is not a ‘sparse’ view. Conscious perception can be as rich and detailed as one likes and this does not require ‘simple seeing’. Of course, the higher-order view is also compatible with the claim that conscious experience is sparse but that is another story.

At any rate, Phillips was not concerned with this debate. He was more concerned with the arguments that Dretske gave for simple seeing. He went through three of Dretske’s arguments and argued that each one had an easy rejoinder from the sparse camp (or the higher-order camp). The first he called ‘conditions’ and involved the claim that when someone looks at a (say) picture for 3-5 minutes scanning every detail to see if there is any difference between the two, we would ordinarily say that they have seen everything in the two pictures. I mean, they were looking right at it and their eyes are not defective! The problem with this line of argument is that it does not rule out the claim that they unconsciously saw the objects in question. The next argument, from blocking, meets the same objection. Dretske claims that if you are looking for your friend and no-one  is standing in front of them blocking them from your sight, then we can say that you did see your friend even if you deny it. The third argument involved that when searching the crowd for your friend you did saw no-one was naked. But this meets a similar objection to the previous two arguments. One could easily not have (consciously) seen one’s friend and just inferred that since you didn’t see anyone naked your friend was naked as well.

Phillips then when on to offer a different way of interpreting simple seeing based on signal detection theory. The basic intuition for simple seeing, as Phillips sees it, lies in the idea that the visual system delivers information to us and then there is what we do with the information. The basic metaphor was a letter being delivered. The delivery of the letter (the placing of it into the mailbox) is one thing, you getting the letter and understanding the contents, is another. Simple seeing can then be thought of as the informative part and the cognitive noticing, attending, higher-order thought, etc, can be thought of as a second independent stage. Signal detection theory, on his view, offers a way to capture this distinction.

Signal detection theory starts with treating the subject as an information channel. They then go on to quantify this, usually by having the subject perform a yes/no task and then looking at how many times they got it right (hits) versus how many times the got it wrong (false alarms). False alarms, specifically, involve the subject saying the see something but being wrong about it, because there was no visual stimulus. This is distinguished from ‘misses’ where there was a target but the subject did not report it. The ‘sensitivity to the world’ is called d’, pronounced “d prime”. On top of this there is another value which is computed called ‘c’. c, for criterion, is thought of as measuring a bias in the subjects response and is typically computed from the average of hits versus false alarms. One can think of the criterion as giving you a sense of how ‘liberal’ or ‘conservative’ the subjects’ response is. If they will say they saw something all the time then the seeming have a very liberal criterion for determine whether they saw something (that is to say they are biased towards saying ‘yes I saw it’ and is presumably mistaking noise for a signal). If they never say the say it then they are very conservative (they are biased towards saying ‘no I didn’t see it). This gives us a sense of how much of the noise in the system the subject treats as actually carrying information.

The suggestion made by Phillips was that this distinction could be used to save Dretske’s view if one took d’ to track simple seeing and c to track they subjects knowledge. He then went on to talk about empirical cases. The first involved memory across saccades and came from Hollingworth and Henderson, Accurate Visual Memory for Previously Attended Objects in Natural Scenes, the second f rom Mitroff and Levin Nothing Compares 2 Views: Change Blindness can occur despite preserved access to the changed information, and the third Ward and Scholl Inattentional blindness reflects limitation on perception, not memory. Each of these can be taken to suggest that there is “evidence of significant underlying sensitivity in [change blindness] and [inattentional blindness],”.

He concluded by talking about blindsight as a possible objection. Dretske wanted to avoid treating blindsight as a case of simple seeing (that is of there being phenomenal consciousness that the subject was unaware (in any cognitive sense) of having). Dretske proposed that what was missing was the availability of the relevant information to act as a justifying reason for their actions. He then went on to suggest various responses to this line of argument. Perhaps blindsight subjects who do not act on the relevant information (say by not grabbing the glass of water in the area of their scotoma) are having the relevant visual experience but are simply unwilling to move (how would we distinguish this from their not having the relevant visual experience)? Perhaps blindsight patients can be thought of as adjusting their criterion and so as choosing the interval with the strongest response and if so this can be thought of as reason responsive. Finally, perhaps, even though they are guessing, they really can be thought of as knowing that the stimulus is there?

In discussion afterwards I asked whether he though this line of argument was susceptible o the same criticism he had leveled against Dretske’s original arguments. One could interpret d’ as tracking conscious visual processing that the subject doesn’t know about, or one could interpret it as tracking the amount of information represented by the subjects mental states independently of what the subject was consciously experiencing (at leas to some extent). So, one might think, the d’ is good so the subject represents information about the stimulus that is able to guide its behavior, but that may be going on while the subject is conscious of some of it but not all of it, or different aspects of it, etc. So there is no real reason to think of d’ as tracking simple (i.e. unconceptualized, unnoticed, uncategorized, etc) content that is conscious as opposed to non-conscious. He responded that he did not think that this constituted an argument. Rather he was trying to offer a model that captured what he took to be Dretske’s basic intuition, which was that there was the information represented by the visual system, which was conscious, and then there was the way that we were aware of that information. This view was sometimes cast as unscientific and he thought of the signal detection material as proving a framework that, if interpreted in the way he suggested, could capture, and thus make scientifically acceptable, something like what Dretske (and other first-order theorists) want.

There was a lot of good discussion, a lot of which I don’t remember, but I do remember Ned Block asking about Phillips’ response to cases like the famous Dretske example of a wall, painted a certain color, having a piece of wallpaper in one spot. The little square of wallpaper has been painted and so is the same color as the wall. If one is looking at the wall and doesn’t see that there is a piece of wallpaper there, does one see (in the simple seeing kind of way) the wallpaper? Phillips seemed to be saying we did (but didn’t know it) and Block asked whether it wasn’t the case that when we se something we represent it visually and Phillips responded by saying that on the kind of view he was suggesting that wasn’t the case. Block didn’t follow up and didn’t come out after so I didn’t get the chance to follow up on that interesting change.

Afterwards I pressed him on the issue I raised. I wondered what he thought about the kinds of cases, discussed by Hakwan Lau (and myself) where the d’ is matched but subjects give differing answers to questions like ‘how confident are you that you saw it?’ or ‘rate the visibility of the thing seen’. In those cases we have, due to matched d’, the same information content (worldly sensitivity) and yet one subject says they are guessing while the other says they are confident they saw it (or rates its visibility lower while the other rates it higher (so as more visible)). Taking this seriously seems to suggest that there is a difference in what it is like for these subjects (a difference in phenomenal consciousness) while there is no difference in what they represent about the world (so at the first-order level). The difference in what it is like for them seems to track the way in which they are aware of the first-order information (as tracked by their visibility/confidence ratings). If so then this suggests that d’ doesn’t track phenomenal consciousness. Phillips responded by suggesting that there may be a way to talk about simple seeing involving differences in what it is like for the subject but didn’t elaborate.

I still am not sure how he responds to the argument Hakwan and I have given. If there is differing conscious experience with the same first-order states each in each case then the difference in conscious experience can only be captured (or is best captured) by some kind of difference in our (higher-order) awareness of those first-order states.

In addition, now that I have thought about it a bit, I wonder how he would respond to Hakwan’s argument (more stemming from his own version of higher-order thought theory) that the setting of the criterion in Phillips’ appeal to it in blindsight cases, depends on a higher-order process and so amounts to a cognitive state having a constitutive role in determining how the first-order state is experienced. This suggests that an ‘austere’ notion of simple seeing where there is no cognitive states involved in phenomenal consciousness is harder to find than Phillips originally thought.