The target article maintains that consciousness emerged only when slow perceptual processing would be useful. But the formation of a conscious percept could be fast even if the vulcanization of that percept is slow. And fast formation may be too fast for a higher-order pointer to form.

Despite the centrality of the notion of representation to its explanations, neuroscience lacks a unified framework for the concepts used to characterize representation, leading to disparate use of terminology and measures associated with representation. To offer clarification, we propose a core set of conceptual dimensions that characterize representations in neuroscience. These dimensions describe relations between a neural response, features that may be represented, and downstream effects of the neural response. A neural response may be shown to be sensitive and specific to a feature, invariant to other features, and functional, which means that it is used downstream in the brain. We use information-theoretic measures to introduce these conceptual dimensions unambiguously and explain how data analysis methods such as correlational analyses, decoding and encoding models, representational similarity analysis, and tests of statistical dependence or adaptation relate to our framework. We consider several canonical examples, including the representation of orientation, numerosity, and spatial location, which illustrate how the evidence put forth in support or criticism of representational conclusions is systematized by our framework. By offering a unified conceptual framework we hope to aid the comparison and integration of results across studies and research groups and to help determine when evidence for a representational conclusion is strong.

A writer grapples with neuroscience's hardest problem.

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

Computational functionalism claims that executing certain computations is sufficient for consciousness, regardless of the physical mechanisms implementing those computations. This view neglects a compelling alternative: that subcomputational biological mechanisms, which realize computational processes, are necessary for consciousness. By contrasting computational roles with their subcomputational biological realizers, I show that there is a systematic tension in our criteria for consciousness: prioritizing computational roles favors consciousness in AI, while prioritizing subcomputational biological realizers favors consciousness in simpler animals. Current theories of consciousness are 'meat-neutral', but if specific physical substrates are necessary, AI may never achieve consciousness. Understanding whether consciousness depends on computational roles, biological realizers, or both, is crucial for assessing the prospects of consciousness in AI and less complex animals.

Disputes between rival theories of consciousness have often centered on whether perceptual contents can be decoded from the prefrontal cortex (PFC). Failures to decode from the PFC are taken to challenge ‘cognitive’ theories of consciousness such as the global workspace theory and higher-order monitoring theories, and decoding successes have been taken to confirm these theories. However, PFC decoding shows both too much and too little. Too much because cognitive theories of consciousness do not need PFC rerepresentation of perceptual contents since pointers to perceptual representations suffice. Too little because there is evidence that PFC decoding of perceptual content reflects postperceptual cognitive representation, such as thoughts that have those perceptual contents rather than conscious percepts.

A neuroscientist searches for the seat of consciousness

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.

A neuroscientist searches for the seat of consciousness

Attention generally enhances both visual performance and subjective appearance. Yet, at matched performance, unattended items can appear more visible than attended ones, a phenomenon called “subjective inflation.” Inflation, however, has only been narrowly tested near detection thresholds, making it unclear whether attention regularly dissociates objective and subjective aspects of perception with broad implications for everyday vision—where attention is usually unevenly distributed—and for studies of consciousness. Here, in four experiments, we tested inattentional inflation over varied stimulus and task conditions, spanning threshold to suprathreshold regimes. Using a new analytic approach to relate objective and subjective reports over full psychometric functions, we measured subjective inflation over wide ranges of matched performance. In all experiments, inattention inflated subjective stimulus visibility. But when subjective reports specified visibility of the task-relevant feature, we only found evidence for inflation at threshold. Thus, what we think we see may regularly dissociate from what we can visually discriminate. ### Competing Interest Statement The authors have declared no competing interest. Templeton World Charity Foundation, https://ror.org/00x0z1472, 0567

Journal Article Responses to my critics Get access Ned Block Ned Block Departments of Philosophy and Psychology, Center for Neural Science New York University, USA ned.block@nyu.edu Search for other works by this author on: Oxford Academic Google Scholar Analysis, Volume 83, Issue 3, July 2023, Pages 575–588, https://doi.org/10.1093/analys/anac058 Published: 22 November 2023

Abstract Although, as argued in Chapter 9, cognitive penetration occurs in the case of ambiguous stimuli especially when feature-based attention is deployed, cognitive penetration is not as common as many suppose. This chapter discusses the question of whether knowledge of what is depicted by a figure has an effect on whether it is seen as a figure or as ground, concluding that classic effects are more likely to be a product of familiarity, a non-cognitive form of memory and of standard gestalt principles than of knowledge. The only clear cases of cognitive penetration in figure/ground perception are effects of feature-based attention of the sort discussed in Chapter 9. Experiments are discussed that appear to show that knowledge of the color of fruits and vegetables affect how they look. The chapter argues that these effects, if they exist, are probably due to associations within the visual system. The chapter also discusses experiments that suggest the effects are not visual at all.

Abstract This chapter distinguishes iconic from discursive representation in the context of a discussion of format and function. It discusses the determinacy of iconic representation, analog magnitude representation, mental imagery, holism, and integral vs. separable dimensions. It rebuts dualistic views of perception that treat object perception as discursive. That discussion concerns object-file representations in perception and memory. The chapter argues that the term “object-file” is a locus of confusion since it can be used to denote nonconceptual nonpropositional perceptual representations and also conceptual propositional representations in working memory. This discussion depends on distinguishing iconic memory, fragile visual short-term memory, and working memory.

Abstract This chapter discusses whether borderline cases challenge a joint in nature, focusing on a borderline case that putatively has properties that are fundamental to both sides. In particular, the issue is discussed of whether the phenomena of “core cognition” have properties that are fundamental to both perception and cognition. Such cases would be candidates for conceptual perception which would impugn the joint in nature that this book argues for. The chapter starts with a discussion of the perception of causation, arguing that the evidence for perceptual representation of causation is now overwhelming and that “core cognition” of causation can be divided into the perceptual and the cognitive. Similar results apply to numerosity. The conclusion is that “core cognition” is a heterogeneous mixture of perception and cognition.