About

Ned Block is the Silver Professor in the Department of Philosophy at New York University, with secondary appointments in Psychology and Neural Science. He also serves as the Co-Director of the Center for Mind, Brain and Consciousness at NYU. His research focuses on the philosophy of perception and the foundations of neuroscience and cognitive science. Prior to joining NYU, Ned Block taught at the Massachusetts Institute of Technology (MIT) for 25 years. He earned his PhD from Harvard University in 1971, where he worked with Hilary Putnam, who was also his undergraduate mentor.

Research topics

• Psychology
• Cognitive psychology
• Cognitive science
• Neuroscience
• Epistemology
• Philosophy
• Social psychology

Selected publications

• The elusive nature of consciousness <b>A World Appears</b> <i>Michael Pollan</i> Penguin, 2026. 320 pp.

  Science · 2026-02-12

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  A writer grapples with neuroscience's hardest problem.

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• Clarifying the conceptual dimensions of representation in neuroscience

  Nature reviews. Neuroscience · 2026-03-20 · 1 citations

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• When awareness outstrips performance: critical tests of subjective inflation under inattention

  bioRxiv (Cold Spring Harbor Laboratory) · 2025-07-04 · 2 citations

  preprintOpen access

  Abstract Visual experience can sometimes depart from visual performance, providing a powerful lens into the mechanisms generating conscious perception. In one proposed dissociation—subjective inflation—unattended locations in the periphery appear stronger than attended ones despite equated performance. Subjective inflation has played a central role in motivating theories of consciousness that reject the sufficiency of sensory signals for conscious perception. Yet the empirical basis for subjective inflation is limited. Here, in a large-scale adversarial collaboration, we conducted four simultaneously-replicated experiments testing the strength, character, and extent of subjective inflation under inattention. We used a new analytic approach to quantify inattentional inflation over full psychometric functions, beyond single matched-performance levels. We found robust inattentional inflation for contrast-dependent and texture-based perception, at and above the visual threshold. However at suprathreshold, we found inattentional inflation for the overall stimulus but not the specific feature relevant for performance. Finally, we establish the unifying principle that inattentional inflation occurs if and only if attention reduces performance thresholds more than visibility thresholds. Thus what we think we see may regularly exceed what we can visually discriminate, placing constraints on theories of conscious perception.

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• Is Consciousness Computational or Biological?

  2025-01-01

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  If consciousness depends on biology rather than computation, could machines ever truly feel—and might simple animals already do so?

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• Can only meat machines be conscious?

  Trends in Cognitive Sciences · 2025-10-07 · 2 citations

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• Responses to critics

  Philosophy and Phenomenological Research · 2024-12-18 · 1 citations

  article1st authorCorresponding

  Responses to replies can be boring if they are about who said what but I'll try to keep my responses interesting by focusing on the most significant issues, putting any textual issues in separate sections that can be skipped. (References to page numbers are to my book (Block 2023) unless specified otherwise.) Jake Beck and Jake Quilty-Dunn make opposite (though compatible) criticisms of my way of drawing the border between perception and cognition. Beck thinks I am wrong about a species of cognition while Quilty-Dunn thinks I am wrong about a species of perception. Beck thinks that cognition can have the properties I regard as constitutive of perception; he thinks my characterization of perception as iconic, non-conceptual and non-propositional also applies to an important species of cognition and that I neglect this species of cognition. Quilty-Dunn thinks that the properties I ascribe to paradigmatic cognition (discursive, conceptual, propositional) apply to an important species of perception—object perception. From my perspective, Beck inflates the category of the non-conceptual, non-propositional and iconic whereas Quilty-Dunn inflates the category of the conceptual, propositional and discursive. Both critiques centrally involve my claim that when perceptual representations are used in cognition, they are enclosed in what I call a cognitive envelope that adds a discursive, conceptual and propositional shell to perceptual representations that do not in themselves have these properties. This challenges Beck because the cognitive aspect of the representations that he emphasizes should be thought of in terms of cognitive envelopes and it challenges Quilty-Dunn because object perception itself is not enclosed in a cognitive envelope unless encoded in working memory. I explain the notion of a cognitive envelope and its relation to working memory in the Précis in the section on what a cognitive envelope is. Please read that before continuing. Encoding in working memory is fast (too fast for me to explain). Perceptual categorization (especially high level perceptual categorization) is fast (too fast for me to explain). I'll start with 1. As I explain in the Précis, I see encoding in working memory in terms of the global workspace model. (I am ignoring “activity-silent” working memory—see the Précis.) Broadcasting in the global workspace takes about 270 ms. at a minimum, so the speed of encoding in working memory is a potential vulnerability for me. Before we get to an explicit discussion of that issue, there are two preliminary issues. The first is whether perception and working memory speak different languages (requiring a time-consuming translation) and the second is what working memory is for. I will proceed to discuss those two issues before getting to an explicit discussion of how fast encoding in working memory really is and why that matters. Does the way perception and cognition interact seem to suggest that they speak different languages and rely on some intermediating translation? Or do they use a common interlingua that allows for free transfer of information? … Our key question: does perception seem to hand information off in a way that suggests a common interlingua, in a way that suggests a … is the information transfer fast the representations at the for cognitive and perceptual the is that a that that perception and cognition speak the a speed when it to the fast speed of encoding perception in working memory. Quilty-Dunn I have a he does This is the of a cognitive envelope my what is enclosed in the cognitive envelope can be iconic representations of but The can be by the the perceptual representations in the of the to be is for to be by to the discursive, conceptual and propositional cognitive in the of the The envelope is by in the global workspace and of that takes as I will explain of perceptual representations in working memory can before I have a because my representations of perception and what is enclosed in working memory. as we will a Before we get to the of how fast perceptual representations can be there is issue, what working memory is for. information of a perceptual to be to a of the perceptual to be used in some of and cognitive that if working memory is for with we it to have the as perception. it is for use in cognition, we it to have the of cognition. as he working memory is for and is that and because if the of object perception is discursive, it the as cognition. I have a different way of and is by the iconic representations enclosed in the working memory envelope and is by the envelope way to the is that my of the working memory aspect of cognition is iconic and I an on to the of how fast of representations in working memory really is and whether it is with my of working memory. I as a memory of a of a that is to a that the the memory by a of of The to key if there a in and the key if there The between of the memory and to ms. at the before the about on the but with there for and of by the at and as that for to make it in working memory. to that of for to be encoded Quilty-Dunn that working memory is fast for is that I can fast because is the of a that before in the global as I will first that I I that working memory iconic representations in a cognitive is the cognitive envelope in this The are to for a and on that This is a cognitive perceptual in the of and have to to and in to cognitive of at the of that the to the of to of the so have to to with these be to that the for the first in is the it takes to and the to the is the it takes to two this be a From the of of the global workspace of the perceptual can be by the in the of the to of the global workspace is of the of global in the that the ms. allows of for in the global workspace before a is the ms. the to make a with the first before the is The that is to memory seem to that is in this is with a in of the in the are encoded but is as the The between these two of on a of the before the for global representations are and of enclosed in a that is that some of the iconic of perception are as in are the perceptual but are by representations is the cognitive This is to my The way I it is that in the global workspace can perceptual representations to cognitive representations and the cognitive that on that have those cognitive As I at the Quilty-Dunn two is to the speed of working memory the to the speed of perceptual the two issues Quilty-Dunn two of how the be with about the speed of iconic be in of with with fast a of that categorization takes of I to that Quilty-Dunn the discussion of fast categorization with that a of by that categorization takes of this and that I discuss see that categorization is fast for it to be by a cognitive and be perception is on the perceptual the that Quilty-Dunn is but I'll that in terms of of this but in the discussion a of with the before in the Précis, a of the can make the first to is the of the a on a and to whether the of the that with as as ms. between and the in the used the but with of that are at on in that a ms. the between and for of a of I in the book in a section The I and I can be on the of see for an is that what is important for the of perceptual categorization is not the of the to but how the is are different because the is in the the Quilty-Dunn but on to me what is and what I is wrong with and on to the different that Quilty-Dunn is and why I I can explain with regard to the in the of the on perception. in a of of of with a at a in the the of the a and the to the of whether there a in the that the the the to a a not the The in these is a of can of it as to for The the of between the and the can see the is that if the to the about the the about ms. and in the for and level perception in the ms. is the of in the first in in terms of that ms. of in is for and the to that the of before the is the of the perception is wrong with this in terms of the is that ms. is the to a but the is not the of the perception of perceptual of the is and that takes before ms. of the and the at in the and in and at high and with of the categorization in the are of for the in and the as as in different in in perception of and way the in be for fast perception of level I discuss for the do not the speed of that the is a of the conceptual category that is the of perception to to a conceptual category the in the but is that an iconic non-conceptual of perception is to the iconic the in the of most of a the categorization be … is whether encoding conceptual is encoding a to the that the for categorization about the as that for and that of representations is iconic is on a by the of the different in that of the in the is a of object perception of is a of and and are iconic level is that the is the for categorization of the of perception. I with Quilty-Dunn that the are in on in and I that in the book the between and about in and not the of categorization of any of these there is to the and and these of representations are in of the The and of how that are they I that Quilty-Dunn should be by this on categorization of and representations on as as and categorization of the in does why the object categorization is important to that of the that Quilty-Dunn is on claim that perceptual categorization takes fast in of that encoding in working memory is fast of the The are not for that The of how a perception takes how encoding in working memory takes are not The of of these is to that perception can in a to as in some the of these of of that a will at of while the representations of at of The of of these is that the the of on because by the that the of the be Quilty-Dunn on the between and level The of the is can be as as as with and what is in is not the speed of categorization but whether is for Quilty-Dunn the by in working memory of the iconic representations of and they are with what he as the representations of is that categorization is a of encoding in working memory. that the that I to have my can the for fast perceptual categorization and for fast perception to working memory. Jake Beck is with my category of cognition. my border is the border between perception and an species of cognition cognition a that perception cognition in terms of perception on for its and whereas cognition does that is but my characterization of as that on the I an to this Beck and I have a a what I am is to the between a and a by the between a and a ignoring the is this category of the that is at issue, the non-conceptual, non-propositional and iconic cognition of and any cognitive Beck thinks are and he is there is an important category of cognition that is non-conceptual, non-propositional and As my is that the category that he is about is enclosed in a cognitive envelope and so not non-conceptual, non-propositional on my I that perception cognition is non-conceptual, propositional and but not conceptual, propositional and is the between what is constitutive and what is non-conceptual, non-propositional and iconic these representations in conceptual, propositional discursive. is in that it not perceptual as when we use perceptual to whether the will the a to the so cognition perceptual so I a cognitive the Précis for the of a cognitive by I on a category of perceptual perceptual and perceptual that be used on in but in any of cognitive I that The use of perceptual representations in is to that cognition can involve iconic the of some of on in the This me to cognition as not non-conceptual, non-propositional and I that these non-conceptual representations are in a conceptual cognitive envelope but I the to they are themselves and the to the of working memory is the The is used by different of and As I in the I representations as representations that can as in I for the that iconic representations enclosed in a cognitive envelope can be is a of whereas are of is a of and on an iconic of a as a of as to have I the first of these are in but not and not the of and I iconic representations enclosed in a cognitive envelope can Beck that and is that there is that and are of propositional as I will explain in the of this this of a is a is and a object is in of the but the so the see it The is and the is they can have the object but they get is so the can see it is start to the This a of to and the of by they in of at the what is are that an but does these a for the that there is a of at this suggest a of in species have to for some some and so it seem that can in I if the of is be but they can be be a and a but it can be The of be a they have is to the my use of the this in and propositional Beck that can be he thinks iconic representations can a and a in propositional not in but in and that for me is not the to that iconic representations in a cognitive envelope can be Beck and I are at with is that have propositional representations before the Précis, I in in seem to that the of the is This at to to if this is these have at a of with a in a in the The is that there is for in and that Beck thinks have propositional there is some for is that it takes before have with on and but I Beck the of this to the that propositional in my to that at the most of before and a at are as that cognition and the cognition of some is and he that have if this in a that perception is is that perception is in he as as not if he on a of he for perception if he with that he to the of cognition, at in and The is that I perception is because it but cognition also so how can it be with the second of the cognition does not are of is that to as I and some some and are of As I it be that are of some to why am I about of and when the of I am not my are in the of of whether a is is also in the of of is a of whether of are for use in and cognitive and are two to the The first is that what he perceptual are as as the they while that on for they are not on for see and can to the perceptual about in they are in my I the of a perceptual on page I as cognitive that is to a perception is a perceptual on that perception. I am a I on the of that perception that there is a I speak of perceptual I am about a cognitive that is by this not be as as it should have the of that I to that the perception while it is of is as as perception. Beck that this of is a category but I perception there can be an iconic that a of ms. of the that Beck is about takes a the discussion on are perception. a about two that see by to use for the is a of that can make when is that be at this of I the between the the between the have different of but for I can do this with my and not with my Beck thinks that to perception if it can be in a and to cognition if it can be in a the of cognition of what is is as as perception. is a in in that is for the in I have it off for because I interesting can be of an in whereas perception is and iconic cognition is of those it is the conceptual, and I and to be a of I do as a of perception and as a of cognition, but I do not as of the of and I those in terms of I discuss of on and those to on to the and that in terms of are in what I is not I am at to explain that while is a of and are a of in the the that I will be are that in propositional and cognitive and I start the section by I have what propositional representations propositional is in in cognitive as and I on to discuss the aspect of that a conceptual, be propositional the that that a is propositional will for some of the As I I a of of the Beck in focusing on whether these should be in terms of I the is a of that that are be enclosed in a as when use to if a will a to this to that perceptual are in working memory. if we to why in working memory if the to a in the global the of perception cognition is by when about perceptual in a he that they are to a that is with the a the this in the is in by a is of conceptual and Beck thinks I to a of he to an is to to a by because he not criticisms that my but he also me how to The he in this is that the of that I use of in what is of in the that are the Both the and the be to be iconic in my but on the of perception is not in the the properties they seem to be that of a does not of a with of a any of allows for of at at first the to these that a is The between the of and the of does not seem and representations of it seem to in how can perceptual representations be start with an of perception the of cognitive perception. on the is a that the can by the between and while on when the The two the of the that the as and in the is by the in are and are the the in are and of the first two the the in are whether and are the (I regard these as different of a to be in the to is to is that for most of perception is of the and that is at the the in be that the of perception of be he is that as in the of perception the and used to perception use working memory the be of the be in working memory by the that is used in Both the and are in working memory while to the while it is the a to be with a As it in the to a emphasizes information when the the section of the book on the I a of that this really is an on the perception of not on cognitive of that I is to this discussion used a in a by a between two the in the in with in that between the two The the of who for that the the in as the and also that the cognitive that the not the a on perception that is not a of cognitive for a I for categorization used on the most is that if a with a of a different that is as a different will to to the but if the is in a different category the that the different category As I in this can be used to the of and this with the in is about this in the is that it memory and so the of conceptual are this a of is as in who perceptual do not the that perception is perceptual there is for perception I a of and and of and perception. perception is a category that is the for in of and to a perceptual category that these and there a to the there is to that perception is how can it be As it is not that this of perception is with the notion of if thinks of the as is not that the notion of does not a The between in can be thought of as to a that the as the of in most of the a in is in the be a is as with regard to a different the with the in my of the of is is a with that can be as of is as an in an to is by a to the of with that the the The by the perception of the takes and so regard some in as of be for any that the of a The of what perceptual are that with the and is that they are for by and at and by in between the as in how can those be how can we explain the that of at the border between are by the border and are to be as in category the with the in memory the to these to what the perceptual to the to some and to the that the This also explain why is at category As at the will to be in different I in the book for a of what perceptual are in the can be by representations for The perceptual can be as an to perceptual categorization if are thought of as the perceptual can be as a of a of perceptual as of suggests that there be a of perception and working memory in terms of that representations with information and to an while they that a not an in memory As representations in the in the of the are and by a that does not cognitive representations in and so it be that representations of the are when the information is of have that on category representations and but information can explain a of perceptual and working memory of of memory and the of to the that category representations are we can question: how is that with iconic be that the representations be iconic The two in the of categorization are and to the are in terms of the of the category of have a high explain why are in that are that are to the in how are the themselves is that the are the that of perception and working memory are and if the representations are not iconic, perception and working memory involve a of and iconic with the in working memory in perception. I have about the is that the for not have to a and for have for and for and have to be at those two and and on between category it also that these when do a numbers in the As I this that the are to of cognitive to the perceptual by the that the are not in should be that this does not apply to the of the in they category at before they any of perception can be in terms of the of in and are in the of the as with with interesting to I to my to my my a in a different and are of have perception for that are not for can see this as the on a that this of representations but there are some perceptual that are the of I am as to whether these really are perceptual as to a is an interesting of whether we can that perception is by is why I the of a on The the of about there is a of the that as that the of that as a different as I do the of a can of perception by the can the be by the I that that is of perception. on in the so they will be the to explain in perception. The applies to to a in the category an to be to be as in the category the on page will a that that the category between and is and to in what as the category that as in the the a category to to level properties. are to be in terms of the I some about the use of in whether the different of a before and to to high level perceptual of the category on the of whether the to in high level properties in level properties and by This is a of vulnerability in the but as I these are on the border of and of perception the of perceptual as iconic I some of the issues he and I will be of use to The by is as I in is to the of whether is whether as is what are and I'll start with but most of what I have to As I in the Précis, I regard as a I in the is a to a is to the as the to to is to as to the relation to and is to of as the there be perceptual that is not to a As I in the first of I regard of perceptual as in terms of to a a perception be can be as the there is this perceptual of is that there is of perceptual perceptual is perceptual will that we can between two different about what those for whether they are I will not be with what the are two of perceptual and This is what most of this is perceptual is a perceptual is a while at the is an that when and when is a and the is a 1. a when the are different and a when the are the an does not at but it can a to perceptual we of an as a it is a the information about is and is is in between and because the and the perceptual is a perceptual of a of the properties that perceptual is perceptual (I will the when it is that I am about perceptual I can the between and in a by to the in This used to that are to a are two of by ms. can be not in the first second The a between the as the the and a This is as a two The is that if there are are in the and that this is in high This of is of what to the that there is as a The by and is that any in that a in the can have a with the important for is the of and perceptual this have to the so this is be that the the be that the the different the to the that and because the to the to the As we will there is a as to whether will see that of on that to that two are different have to a relation between on be a of be be this about the between and I a of and I that is and the but when I see I the and I is this these are at as I the This is not my that is and the if I can ascribe to but not the that as and perceptual are As we have two is a because the to a a a two is with two on the and on the and to a on the the the on the in are a and to whether it a a the a two are and the to a the of the to two are the these involve are some as as a is a that in the of of is and is of the me to that in the perception are on in 2023) a between and is the to that perceptual on perceptual a and it that and to is this perception is it to perceptual perceptual Or is it the in that are This is a to responses in are on I of any that this and with two at different a for by a for for key for and key for This is a in that it a any to of the they for key for the second and key for the first This is a also the on whether the of the of the and of two there two for

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• Précis of <i>The Border between Seeing and Thinking</i>

  Philosophy and Phenomenological Research · 2024-12-18 · 2 citations

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  Despite the title, this isn't so much a précis as an update about my current thinking on some of the most important issues of the book as they are relevant to the excellent critiques in this issue. (References to page numbers are to my book (Block, 2023a) unless specified otherwise.) The book is mainly about perception, the best understood aspect of the mind, and hence our best window into how the mind works and how it is grounded in the brain (Mandelbaum, 2024). The book starts with armchair indicators of perception, then moves to scientific indicators of perception, adaptation, speed, pop-out and illusory contours, using them to try to pinpoint the most basic characterization of perception and cognition. Of these indicators, the most controversial has been adaptation, mainly because of two issues: whether there can be cognitive adaptation (Helton, 2016) and whether all perceptual systems show it (Block, 2023d; Phillips & Firestone, 2023), The main claim of the book is that perception is constitutively iconic, non-conceptual and non-propositional while cognition is paradigmatically (but not constitutively) discursive (non-iconic), conceptual and propositional. Perception constitutively has these properties in that its nature does not allow for discursive, conceptual or propositional representation. Cognition is necessarily discursive, conceptual and propositional but it also can make use of perceptual materials in a cognitive envelope, as when we use perceptual imagery in the course of reasoning. This is my main approach to the perception/cognition border though I also accept a moderate level of modularity of perception (Mandelbaum, 2024), as explained in Chapter 11. Much of the book was devoted to distinguishing between low-level and high-level perception where low-level perceptual representations are the products of sensory transduction that are causally involved in the production of other (mid and high-level) perceptual representations. I argued that there are high-level perceptual representations and discussed how to distinguish them from cognitive representations, most importantly minimal immediate direct perceptual judgments. The latter notion comes up briefly in my reply to Jake Beck. I argued in Chapter 6 that infant color perception is non-conceptual on the basis of the fact that the infants in question do not normally deploy and probably don't have any concept of color. (My argument has been critiqued in (Green, 2024). I argued that the point generalizes at least to adult color perception. There has been a lot of controversy over claims that perception is discursive, conceptual and propositional (Block, 2023c; Quilty-Dunn et al., 2023). Jake Quilty-Dunn and EJ Green (Green & Quilty-Dunn, 2021; Quilty-Dunn & Green, 2021) argue that object perception—but not perception of features such as color– is discursive, conceptual and propositional, so although they are opposed to my main claims, non-conceptual color perception would be compatible with their view (Block, 2023b). One chapter of the book is devoted to core cognition. It has been argued that core cognition is a third category, intermediate between perception and cognition, but I argued that core cognition is a mongrel notion whose phenomena can be apportioned between perception and cognition, and in that sense core cognition is a heterogeneous mixture. Much of the book was devoted to perception, irrespective of whether the perception is conscious or unconscious. I argued that this perspective has a number of significant advantages in uncovering ideas that can then be applied in arguing against cognitive theories of consciousness. Although I argue against cognitive theories of consciousness in the book, I have recently started taking them more seriously, having been persuaded by the advantages of “pointer” versions of these theories (Block, 2024b; Michel, forthcoming). The concept in the book that is most in need of further explanation is the notion of a cognitive envelope and its relation to perception and working memory. I turn to that topic now. The term ‘cognitive envelope’ is best explained with respect to the “global neuronal workspace”, often offered as a theory of consciousness (Dehaene, 2014) but which I argue is better thought of as a theory of how perceptual representations are conceptualized. The idea of the global neuronal workspace is that activated representations in perceptual areas compete with one another, with a small number of “neural coalitions” winning out that then trigger “ignition”, linking them up with frontoparietal circuits via long range “workspace neurons” that connect the front with the back of the head1 (See pages 7–8 and p. 320 (of the book).) These activated neural coalitions involving both the front and back of the head make the contents of the representations immediately available to a range of cognitive faculties, reasoning, reporting, deciding, and the like, at least in creatures like adult humans that have these cognitive faculties. It is the links to cognitive faculties in the global workspace that constitute the “cognitive envelope”. This is all illustrated in Figure 1 (from early in the book—p.7). The concentric rings represent levels of processing. (see pp. 83–84 on the visual hierarchy.) The outer ring represents the sensory surfaces of the body whereas the inner rings represent frontal-parietal circuits that govern thinking, decision-making, planning and other cognitive functions. Processors are indicated by small disks, links between them by lines—activated processors and links are darker. Activations in the sensory rings compete for dominance, triggering mutually reinforcing reverberating activity linking inner and outer rings. What Figure 1 illustrates is that when sensory surfaces are stimulated, they cause activations of processors, indicated by darker disks. Those activated processors activate other processors via activated links. Some of those activations die out but others form mutually reinforcing coalitions—involving both feedforward and feedback connections– indicated by the large ovals, and some or all of those trigger long range activations in frontal/parietal workspace areas. We can think of global broadcasting in terms of 4 stages: (1) perceptual representations competing (outer dotted rings), (2) some mutually reinforcing coalitions winning (dark ovals), (3) winning coalitions triggering workspace activations (inside the central circle), (4) leading to mutually reinforcing neural activations involving both the front and back of the head. While the details of Dehaene's model are controversial, I think the broad outline of these stages would be widely accepted. Broadcasting in the global workspace is the main mechanism of “working memory”, the active maintenance of representations for use in reasoning. It is that use in reasoning that determines that they are in part discursive, conceptual and propositional. There may however be broadcasting in creatures whose reasoning capacities are substantially iconic. Ants and bees for example have famously prodigious memory capacities (Gallistel & King, 2011) but perhaps little or nothing in the way of propositional reasoning. Some of the reasoning abilities in infants may also be primarily iconic. I defined “working memory” as “active”. Sometimes the term “working memory” is used in a looser sense to refer to any temporarily retained perceptual information that can be used in a subsequent task. Active working memory is conscious but several studies suggest maintenance of information in unconscious perception for up to 4 seconds in what is sometimes termed “activity-silent working memory” (Soto et al., 2011) or a “blindsight effect” (Trübutschek et al., 2017). Subjects could localize a target presented in unconscious perception better than chance 4 seconds after presentation of the stimulus. There is some evidence that this information is maintained in temporarily changed synaptic weights (Trübutschek et al., 2017) but later work suggests that perhaps a low level of activation is involved (Barbosa et al., 2021; Fields, 2022) This form of information persistence is totally different in its fundamental properties from active working memory and it is just confusing to give it the same name (Carruthers, 2015, p. 91). I will ignore it in what follows. As I emphasize in the book, working memory is required for any content-based reasoning in which premises are put together to reason to a conclusion because the premises have to be held in working memory. How early do babies show signs of content-based reasoning? Kiley Hamlin showed 6 month old babies events involving small colored squares, triangles and circles with eyes made of wood. One figure, say the triangle, appeared to be “trying” to get up a slope. Later, another figure played the role of a “helper”, pushing the triangle up the slope while another played the hinderer, pushing the triangle down the slope. When offered the choice of blocks in these shapes, the babies preferred the helper and rejected the hinderer. They distinguished accidental from intentional helping and hindering (Hamlin et al., 2007). Most importantly for content-based reasoning, the infants preferred the hinderer of the hinderer. This was replicated with 8 month old bilinguals (Singh, 2020). 8 month olds were shown two scenarios in which an agent tried but failed to help, or alternatively, to hinder a “protagonist” open a box. Even though the protagonist did open the box, the infants preferred the helper to the hinderer. (Woo et al., 2022) report many results of this sort and they address concerns about replication showing that the main results have been replicated many times even though there have been some notable failures to replicate. My conclusion is that these results provide some reason to believe that the infants have content-based reasoning involving multiple items in working memory, categorized appropriately, put together to draw conclusions. Leaner accounts of this thinking in purely iconic terms are not ruled out however. This issue will come up in my reply to Jake Beck. What I've said so far might suggest that my view of working memory is that it is a hybrid: perceptual representations pretty much unchanged are part of a reverberant (self-sustaining feed forward and back) network with cognitive representations, allowing the perceptual representations to participate in perceptually based reasoning. However, part of this picture is likely wrong. The accepted view of working memory has shifted radically in the last few years. The outmoded “sensory recruitment” view of working memory (D'Esposito & Postle, 2015) assumed it could be understood in terms of purely perceptual representations and so could be studied using stimuli of shapes or colored circles or oriented lines. It was assumed that working memory capacity was fixed in terms of numbers of objects or a fixed pool of resources for each visual feature (Asp et al., 2021). More recent approaches (Chung et al., in press; Duan & Curtis, 2024; Kwak & Curtis, 2022) have treated working memory representations as task specific and as linked to knowledge structures in long term memory. Asp et al. presented ambiguous “Mooney faces” and related figures in paradigms in which the same figure would be seen as a face by some subjects and as a meaningless pattern by others. They found across a number of different methods higher working memory capacity for faces vs the same figures as meaningless patterns. As Chung et al. note, other studies have shown that when stimuli are seen in terms of semantically meaningful categories, working memory capacities are increased. One strong piece of evidence in favor of the sensory recruitment hypothesis was that working memory representations of perception could be decoded using brain imaging from the earliest visual area V1. However (Duan & Curtis, 2024) showed that even for oriented grids, the working memory representations in V1 are reformatted versions of the perceptual representations in V1. They showed this by biasing the stimuli with a sophisticated form of an “aperture bias” which in its simplest form is just looking at the stimuli through a shaped aperture which can have the same or orthogonal orientation of the grid. They used aperature biases that could be the same orientation as the stimuli or orthogonal to the orientation of the stimuli and contrasted a perception task with a working memory task. They found that the aperture biases affected the decoding of the perceptual representations in V1 in a perception task, but not in a comparable working memory task. When they trained a decoder on the perceptual representation of a grating in V1, the same decoder only worked during the working memory representation if the aperture bias was aligned with the grid. They conclude (p.1), “These results provide strong evidence that visual WM representations are abstractions of percepts, immune to perceptual aperture biases…” Working memory is highly resistant to masking of all kinds (Teeuwen et al., 2021). (A mask is a stimulus presented after (or before) a target stimulus that makes the target stimulus harder to see.) But perceptual representations at different stages in the processing stream can be obliterated by the right kinds of masks at different times after the stimulus. Maguire & Howe showed that lines and edges work well as masks when the perception is being processed by early vision, texture masks work well 50 ms later, and shaped objects mask perceptions during shape processing. Because of the need for visual cortex to process ongoing perception, working memory representations are often recoded outside the classic visual cortex (Rademaker et al., 2019) Color representations in perception when moved to working memory are biased away from category boundaries and towards category centers (Bae et al., 2015) Working memory representations for colors are related to color names in a way that perceptual representations of color are not. (Hasantash & Afraz, 2020) showed that although knowing more color names makes for more color representations in working memory, it has no effect on perceptual color matching. Also, subjects who have more color names in a particular area of the color wheel can hold more of those colors in working memory, but they did not do better on those colors in a perceptual matching task. Working memory representations are coarse grained. For example, we can hear many more pitches and see many more colors than we can hold in temporary memory Fundamental computational features of perception are absent in working memory representations. One such computational feature is divisive normalization, a computation an aspect of how the perceptions of two items one another, (See p. and Chapter of is illustrated in Figure where it the of the central on the right where it is with the but not on the where the two are at Figure will see that the central in than the orthogonal central et al. et al., showed subjects central and of or one after the by one They found when the were presented at the same but not by 1 one to be held in working memory. They (p.1), memory representations a different of computational from normalization, a visual Working memory representations not to the iconic memory representations of perception. showed the classic iconic memory effect by subjects with an of For example, presented of 4 in each of a presentation of the subjects could or 4 even though they said they could see all or most of the showed that they a representation of all or most of the as presented the then after the was an for one of the found that subjects could name or 4 from any This classic iconic memory does not work when the is presented after they moved their eyes to a using a working memory representation of the (See and memory is much more perceptual than working memory, a fact many that they have different Working memory with to that emphasize a pool of and also when subjects are to more items et al., 2019) showed subjects colored briefly and after a no up to 1 a where there been a colored The task was to pinpoint the color on a color found that as subjects could colors but with no of model the results much better than a model of the sort one would with working memory, a different pattern for the iconic memory and visual term memory in these Kwak and & Curtis, 2022) showed that perceptual representations are in working memory on the task. They showed subjects with a in one and oriented in The task was to the orientation of the or the grid. They the subjects during the that they could not the between the neural representations of these different the perceptual representations more in working memory. The cognitive of the task can in information to the working memory so that is a reason for thinking the process of the perception is in the sense of 2023), These between perception and working memory do not show a in and even if there is a in it could be the category of iconic representation than a of iconic into discursive representation. The perceptual representations of working memory may be or iconic, while in a cognitive envelope by the reverberating circuits involving cognition as in Figure Those cognition circuits will normally propositional reasoning, at least in adult content-based reasoning working memory. representations are held in working memory in a cognitive envelope in which the nature of the representations is more than perceptual representations and in which these representations are to a of cognitive in the global I was of much of this when I the book in but in the last few the evidence has in that even the most basic perceptions like the perception of oriented lines are recoded when used in reasoning. This has my that there are any perceptual representations used in cognition. in representations as to in properties in a way that is to the of For example, as objects are perceptual representations of the in a way that is to the of in representations to the that is in a way that on the of the properties are by representations that of those has a notion of also from not seen book my book was in notion in a of from the main is that that the relation be in a way that is to and my I give what I as a highly example in which in in are by that represent and of a at in the I to think that it can use irrespective of as I that we can an visual that an iconic both in and in this issue the claim that perception is iconic in my that adaptation provide some evidence that there is a perceptual category by and might be for or that are in but what about and that are not. How can there be an iconic representation that is between and suggests some of the results that I as and in need of further The most is that there are between and The mechanism of the might be that one any the representation at both and with the representation between the The details are in (Block, p. to some of the evidence for iconic representation in has long the role of iconic representations in reasoning. One role is the use of some in Jake in this issue. But there is another that has that also is substantially iconic, what the in which from in working memory represent the one of if infants see an put one large piece of in one and small in the other infants to the with more area showing the is being with the What these representations are in the is that if there are 4 or more in one of the the choice to As I for kinds of the working memory has a capacity of about so to chance that is in The has up to for and those can represent in an iconic further example of this is when the are a a and a the having seen those in the box. The is if items that like those are not there on this with 4 items than The and picture iconic representation at the level of the in working memory, but there is also For example, an in which there are two into which a can but what is in the objects have been put in the the to into the whereas if the number of items is 4 or the to chance as just The working memory representations as a the items in the as a in respect of More recent by and their et al., et al., show other For example, an to task in which there are two in one there are items all the in another all are different from one another, with no two the Subjects are one of the and are to from a number of which one the The intermediate all same with all the of all they their on all not the no two the or not all the to the two of the of The and to a of that is their are by all the same no two the same and intermediate the same lines. The point is that is a that properties of the and so iconic. these phenomena involving iconic representation in thinking in and also to the made by Jake in and in that there is an important category of non-conceptual and non-propositional My is that in of the sort just the iconic representations are in a cognitive envelope, so they are not non-conceptual or I do however that I might have the of iconic representation in thought but in many the thought of and babies over when they a form of in a cognitive envelope that a discursive, propositional and conceptual aspect to the Chapter that there is no fact of the as to whether perception is constitutively and then on pages I argued that both perceptual and perceptual are fundamental to perception and there is no fact of the as to whether one is more basic than the This is probably the topic on which my have the I think the conclusion is right but for different than in the book, and the concept of perceptual which I as in the book I see as importantly My of the to and is mainly with the issue than my with et al. and it is the of my than into the issues I to the

  PublisherDOI

• States of mind <b>Then I Am Myself the World: What Consciousness Is and How to Expand It</b> <i>Christof Koch</i> Basic Books, 2024. 288 pp.

  Science · 2024-05-09

  article1st authorCorresponding

  A neuroscientist searches for the seat of consciousness.

  PublisherDOI

• CONSCIOUSNESS, BIG SCIENCE, AND CONCEPTUAL CLARITY

  Princeton University Press eBooks · 2024-04-30

  book-chapter1st authorCorresponding
  PublisherDOI

• Memory representations during slow change blindness

  Journal of Vision · 2024-09-10 · 1 citations

  articleOpen access

  Classic change blindness is the phenomenon where seemingly obvious changes that coincide with visual disruptions (such as blinks or brief blanks) go unnoticed by an attentive observer. Some early work into the causes of classic change blindness suggested that any pre-change stimulus representation is overwritten by a representation of the altered post-change stimulus, preventing change detection. However, recent work revealed that, even when observers do maintain memory representations of both the pre- and post-change stimulus states, they can still miss the change, suggesting that change blindness can also arise from a failure to compare the stored representations. Here, we studied slow change blindness, a related phenomenon that occurs even in the absence of visual disruptions when the change occurs sufficiently slowly, to determine whether it could be explained by conclusions from classic change blindness. Across three different slow change blindness experiments we found that observers who consistently failed to notice the change had access to at least two memory representations of the changing display. One representation was precise but short lived: a detailed representation of the more recent stimulus states, but fragile. The other representation lasted longer but was fairly general: stable but too coarse to differentiate the various stages of the change. These findings suggest that, although multiple representations are formed, the failure to compare hypotheses might not explain slow change blindness; even if a comparison were made, the representations would be too sparse (longer term stores) or too fragile (short-lived stores) for such comparison to inform about the change.

  PublisherOA PDFDOI

Frequent coauthors

• Rachel N. Denison

  Boston University

  110 shared

• David L. Barack

  102 shared

• Edgar Y. Walker

  University of Washington

  102 shared

• Stephan Pohl

  102 shared

• Wei Ji

  New York University

  101 shared

• Jennifer Lee

  Tufts University

  101 shared

• Florent Meyniel

  Cognitive Neuroimaging Lab

  17 shared

• Biyu J. He

  New York University

  8 shared

Education

• PhD, Philosophy

  Harvard University

  1971