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In this article I explore a number of questions that have not been adequately investigated in philosophy of mind circles: are minds located in the same place as the brains (or other computing machinery) supporting them? Must they exist at the same location as the body? Must they exist at the same time? Could a single mind be implemented in multiple brains, or multiple minds in a single brain? Under what conditions might a single mind persist despite being implemented successively in different brains? What contributions do features of the computing machinery make to these questions, compared to the contribution made by the body and embedded point of view? Some of these questions have been touched on previously, but there hasn't been any attempt at a systematic analysis of the various consequences that different approaches in the philosophy of mind have for how the spatiotemporal location, synchronic individuation and diachronic identity of minds relates to the spatiotemporal location, synchronic individuation, and diachronic identity of both the implementing computational machinery and the embodied embedded point of view. I make a first stab at such an analysis by discussing a variety of thought experiments in which such questions of location, individuation, and identity arise, and I explore how various approaches to understanding the mind – identity theoretic, functionalist, contentualist, embodied/embedded/extended, and so forth – would respond to such situations. A number of novel issues emerge, and some surprising affinities are revealed.
The nature of temporal experience is typically explained in one of a small number of ways, most are versions of either retentionalism or extensionalism. After describing these, I make a distinction between two kinds of temporal character that could structure temporal experience: A-ish contents are those that present events as structured in past/present/future terms, and B-ish contents are those that present events as structured in earlier-than/later-than/simultaneous-with relations. There are a few exceptions, but most of the literature ignores this distinction, and silently assumes temporal experience is A-ish. I then argue that temporal character is not scale invariant, but rather that temporal experience is A-ish at larger scales (a few hundred milliseconds and above), and B-ish at smaller scales. I then point out that this scale non-invariance opens the possibility of hybrid views. I clarify (or modify, depending on how you want to frame it) my own view (Grush 2005, 2007) as a hybrid view, according to which temporal experience is B-ish at small scales – and at this scale my trajectory estimation model (TEM, a version of reteniotnalism) applies – but A-ish at larger scales, and at the larger scale my TEM does not apply. I then motivate this hybrid position by first defending it against arguments that have tried to show that the TEM is untenable. Since the hybrid view has TEM as its small-scale component, it must address this objection. I then put pressure on the main alternative account, extentionalism, by showing that its proponents have not adequately dealt with the problem of temporal illusions. The result is a new theory (perhaps characterizable as a refined version of my prior theory) motivated by i) explaining its virtues, ii) showing that objections to it can be met, and iii) showing that objections to its main competitors have not been met.
Action is a means of acquiring perceptual information about the environment. Turning around, for example, alters your spatial relations to surrounding objects and, hence, which of their properties you visually perceive. Moving your hand over an object’s surface enables you to feel its shape, temperature, and texture. Sniffing and walking around a room enables you to track down the source of an unpleasant smell. Active or passive movements of the body can also generate useful sources of perceptual information (Gibson 1966, 1979). The pattern of optic flow in the retinal image produced by forward locomotion, for example, contains information about the direction in which you are heading, while motion parallax is a “cue” used by the visual system to estimate the relative distances of objects in your field of view. In these uncontroversial ways and others, perception is instrumentally dependent on action. According to an explanatory framework that Susan Hurley (1998) dubs the “Input-Output Picture”, the dependence of perception on action is purely instrumental: "Movement can alter sensory inputs and so result in different perceptions… changes in output are merely a means to changes in input, on which perception depends directly." (1998: 342) The action-based theories of perception, reviewed in this entry, challenge the Input-Output Picture. They maintain that perception can also depend in a noninstrumental or constitutive way on action (or, more generally, on capacities for object-directed motor control). This position has taken many different forms in the history of philosophy and psychology. Most action-based theories of perception in the last 300 years, however, have looked to action in order to explain how vision, in particular, acquires either all or some of its spatial representational content. Accordingly, these are the theories on which we shall focus here. We begin in Section 1 by discussing George Berkeley’s Towards a New Theory of Vision (1709), the historical locus classicus of action-based theories of perception, and one of the most influential texts on vision ever written. Berkeley argues that the basic or “proper” deliverance of vision is not an arrangement of voluminous objects in three-dimensional space, but rather a two-dimensional manifold of light and color. We then turn to a discussion of Lotze, Helmholtz, and the local sign doctrine. The “local signs” were felt cues for the mind to know what sort of spatial content to imbue visual experience with. For Lotze, these cues were “inflowing” kinaesthetic feelings that result from actually moving the eyes, while, for Helmholtz, they were “outflowing” motor commands sent to move the eyes. In Section 2, we discuss sensorimotor contingency theories, which became prominent in the 20th century. These views maintain that an ability to predict the sensory consequences of self-initiated actions is necessary for perception. Among the motivations for this family of theories is the problem of visual direction constancy—why do objects appear to be stationary even though the locations on the retina to which they reflect light change with every eye movement?—as well as experiments on adaptation to optical rearrangement devices (ORDs) and sensory substitution. Section 3 examines two other important 20th century theories. According to what we shall call the motor component theory, efference copies generated in the oculomotor system and/or proprioceptive feedback from eye-movements are used together with incoming sensory inputs to determine the spatial attributes of perceived objects. Efferent readiness theories, by contrast, look to the particular ways in which perceptual states prepare the observer to move and act in relation to the environment. The modest readiness theory, as we shall call it, claims that the way an object’s spatial attributes are represented in visual experience can be modulated by one or another form of covert action planning. The bold readiness theory argues for the stronger claim that perception just is covert readiness for action. In Section 4, we move to the disposition theory, most influentially articulated by Gareth Evans (1982, 1985), but more recently defended by Rick Grush (2000, 2007). Evans’ theory is, at its core, very similar to the bold efferent readiness theory. There are some notable differences, though. Evans’ account is more finely articulated in some philosophical respects. It also does not posit a reduction of perception to behavioral dispositions, but rather posits that certain complicated relations between perceptual input and behavioral provide spatial content. Grush proposes a very specific theory that is like Evans’ in that it does not posit a reduction, but unlike Evans’ view, does not put behavioral dispositions and sensory input on an undifferentiated footing.
This paper will have three substantive sections, all organized around an interdisciplinary understanding of demonstrative reference. Section 2 will focus on perception, and in particular perceptual mechanisms that allow us to latch onto entities in the environment as candidates for thought or reference. Our point here will be brief and, once made, we hope uncontroversial: location is not – current thinking notwithstanding – the key to understanding how perceptual mechanisms single out their accusatives. Rather, it is Gestalt criteria, or similar low-level principles, that do this. Given the way research is currently most commonly preformed, it is easy to see how this could be missed or ignored. But the focus on location is (at least in part) an artifact of choices about research. In any case, we can see that it is incorrect. Our conclusion will be: the basic perceptual accusatives, those entities, broadly understood, which are isolated and tracked by the perceptual system, are not physical objects, or even Spelke-objects or ‘proto-objects’, or even locations in visual space. They are rather what we will call gobjects (for Gestalt object), which is anything isolated by Gestalt criteria. These often, but not always, involve space, hence the confusion. The focus on vision of most work in this area has aided this error. In Section 3 we will turn from perceptual psychology to language, and in particular to an initial exploration of exophoric demonstrative reference. The goal of this section will also be straight-forward: even a casual look at actual language makes clear that demonstrative reference felicitously tracks the full range of gobjects, physical, spatial, Spelke-objects, non-visual and non-spatial gobjects. Linguistic demonstratives, like perceptual systems, are not beholden to space or location. In Section 4 we turn from these brief preliminary points to a fuller discussion of demonstrative semantics, by way of outlining an account of the semantics of natural language demonstratives we develop elsewhere. The target of this account is the core semantic value of demonstrative expressions in natural language, both exophoric and endophoric. As will emerge, an adequate account of the semantics of demonstratives will interface only minimally with work on object perception, though there will be a great deal of interface with other kinds of empirical research.
Six hypotheses about the relation between the temporal content of perception and the temporality of perceptual processes are identified and discussed. The positions are determined by different stands on three questions: whether the content of perception is an interval or an instant; whether it is a passive reflection or an active construction, and whether or not it is purposefully delayed. The trajectory estimation model, according to which perceptual content is a non-delayed, actively constructed interval, is articulated and defended against the other positions. The main tool used in defending this approach is the existence of certain kinds of temporal illusion, situations in which the apparent temporal features of the perceived situation differs the temporal features of the situation itself.
In this article I outline, apply, and defend a theory of natural representation. The main consequences of this theory are: (i) representational status is a matter of how physical entities are used, and specifically is not a matter of causation, nomic relations with the intentional object, or information; (ii) there are genuine (brain‐) internal representations; (iii) such representations are really representations, and not just farcical pseudo‐representations, such as attractors, principal components, state‐space partitions, or what‐have‐you; and (iv) the theory allows us to sharply distinguish those complex behaviors which are genuinely cognitive from those which are merely complex and adaptive.
The problem of how physical systems, such as brains, come to represent themselves as subjects in an objective world is addressed. I develop an account of the requirements for this ability that draws on and refines work in a philosophical tradition that runs from Kant through Peter Strawson to Gareth Evans. The basic idea is that the ability to represent oneself as a subject in a world whose existence is independent of oneself involves the ability to represent space, and in particular, to represent oneself as one object among others in an objective spatial realm. In parallel, I provide an account of how this ability, and the mechanisms that support it, are realized neurobiologically. This aspect of the article draws on, and refines, work done in the neurobiology and psychology of egocentric and allocentric spatial representation.
I argue against a growing radical trend in current theoretical cognitive science that moves from the premises of embedded cognition, embodied cognition, dynamical systems theory and/or situated robotics to conclusions either to the effect that the mind is not in the brain or that cognition does not require representation, or both. I unearth the considerations at the foundation of this view: Haugeland’s bandwidth-component argument to the effect that the brain is not a component in cognitive activity, and arguments inspired by dynamical systems theory and situated robotics to the effect that cognitive activity does not involve representations. Both of these strands depend not only on a shift of emphasis from higher cognitive functions to things like sensorimotor processes, but also depend on a certain understanding of how sensorimotor processes are implemented - as closed-loop control systems. I describe a much more sophisticated model of sensorimotor processing that is not only more powerful and robust than simple closed-loop control, but for which there is great evidence that it is implemented in the nervous system. This is the emulation theory of representation, according to which the brain constructs inner dynamical models, or emulators, of the body and environment which are used in parallel with the body and environment to enhance motor control and perception and to provide faster feedback during motor processes, and can be run off-line to produce imagery and evaluate sensorimotor counterfactuals. I then show that the emulation framework is immune to the radical arguments, and makes apparent why the brain is a component in the cognitive activity, and exactly what the representations are in sensorimotor control.
The emulation theory of representation is developed and explored as a framework that can revealingly synthesize a wide vari- ety of representational functions of the brain. The framework is based on constructs from control theory (forward models) and signal processing (Kalman filters). The idea is that in addition to simply engaging with the body and environment, the brain constructs neural circuits that act as models of the body and environment. During overt sensorimotor engagement, these models are driven by efference copies in parallel with the body and environment, in order to provide expectations of the sensory feedback, and to enhance and process sensory information. These models can also be run off-line in order to produce imagery, estimate outcomes of different actions, and eval- uate and develop motor plans. The framework is initially developed within the context of motor control, where it has been shown that inner models running in parallel with the body can reduce the effects of feedback delay problems. The same mechanisms can account for motor imagery as the off-line driving of the emulator via efference copies. The framework is extended to account for visual imagery as the off-line driving of an emulator of the motor-visual loop. I also show how such systems can provide for amodal spatial imagery. Per- ception, including visual perception, results from such models being used to form expectations of, and to interpret, sensory input. I close by briefly outlining other cognitive functions that might also be synthesized within this framework, including reasoning, theory of mind phenomena, and language.
The question of whether time is its own best representation is explored. Though there is theoretical debate between proponents of internal models and embedded cognition proponents (e.g. Brooks R 1991 Artificial Intelligence 47 139–59) concerning whether the world is its own best model, proponents of internal models are often content to let time be its own best representation. This happens via the time update of the model that simply allows the model’s state to evolve along with the state of the modeled domain. I argue that this is neither necessary nor advisable. I show that this is not necessary by describing how internal modeling approaches can be generalized to schemes that explicitly represent time by maintaining trajectory estimates rather than state estimates. Though there are a variety of ways this could be done, I illustrate the proposal with a scheme that combines filtering, smoothing and prediction to maintain an estimate of the modeled domain’s trajectory over time. I show that letting time be its own representation is not advisable by showing how trajectory estimation schemes can provide accounts of temporal illusions, such as apparent motion, that pose serious difficulties for any scheme that lets time be its own representation.
A number of recent attempts to bridge Husserlian phenomenology of time consciousness and contemporary tools and results from cognitive science or computational neuroscience are described and critiqued. An alternate proposal is outlined that lacks the weaknesses of existing accounts.
Berkeley’s Essay Towards a New Theory of Vision (NTV) presents a theory of various aspects of the spatial content of visual experience that attempts to undercut not only the optico-geometric accounts of, e.g., Descartes and Malebranche, but also elements of the empiricist account of Locke. My task in this paper is to shed light on some features of Berkeley’s account that have not been adequately appreciated. This paper is organized as follows. Section 2 will discuss Locke’s account of the spatiality of vision in Book II of the Essay. The optico-geometric approach of, e.g., Descartes and Malebranche credits subjects (or their visual systems) with a priori geometrical knowledge by way of which the spatial features of their environments are deduced from, inter alia, the nature of the immediate visual input, the distance between the eyes, and the eyes’ vergence angle. in contrast, Locke’s empiricism motivates an approach according to which spatial features of visual perception are either directly given in perception (viz. spatial information relating to features of the visual environment in the breadth and height dimensions), or are learned through experience—as when features such as shading gradients available on the two-dimensional “sense datum screen” come to be associated with the dimension of depth. In section 3, I turn to Berkeley’s NTV. After a brief preliminary discussion in section 3.2 of the initial sections of NTV that deal with the issue of depth in a way that is essentially a more detailed version of Locke’s account, section 3.3 discerns two conflated but distinguishable considerations that Berkeley provides to the effect that depth is not a proper object of vision. I then turn, in sections 3.4 to 3.6, to what is the central issue of this paper: Berkeley’s discussion of the spatial axes of breadth and height. This is where the problems arise, for on the one hand, Berkeley is motivated to deny Locke’s assumption that we are through vision immediately aware of a two-dimensional sense datum plane, for the spatiality of this plane, as a common sensible available to both vision and touch and hence the exclusive province of neither, would be an abstract idea. But on the other hand, he frequently uses language that suggests he is crediting vision with just such planar content. The first major strand of the critical discussion of Berkeley in section 3.4 will be a critique of his negative account to the effect that planar content is not directly given through the modality of vision, where it will be argued that Berkeley’s argument fails because of an unnoticed ambiguity—the same ambiguity that was shown in section 3.3 to be present, but relatively harmlessly so, in his discussion of depth. The second major strand, spanning sections 3.5 and 3.6, concerns Berkeley’s positive account of the apparent planar content of visual experience. I argue that his positive account of vision cannot be formulated in such a way that is both adequate as an account of actual human vision and does not make surreptitious appeal to precisely the planar content the dismissal of which is its goal—and this is true even on the sympathetic reconstructions that have been offered recently by Atherton and Schwartz. In a brief, final section 4, I make explicit what alterations would have to be made to Berkeley’s position in order to render it viable, and underscore the respect in which it has been vindicated by recent work in perception.
Gareth Evans’ account of Identification-freedom (IF), which he develops in Chapters 6 and 7 of The Varieties of Reference (henceforth VR) is almost universally misunderstood. My exegesis of Evans’ account — like any non-trivial exegesis — goes somewhat beyond anything Evans overtly says. That Evans did not explicitly put the pieces together in the way I suggest they fit no doubt contributes to the widespread misunderstanding of his views. But I am confident that once my interpretation is on the table it will be post hoc obvious that it really is the correct interpretation Evans’ account.
I call the wave-collapse illusion – a less radical cousin of the refrigerator light illusion – to the effect that transitions from generic to detailed phenomenology are not noticed as phenomenal changes. Change blindness and inattentional blindness can be analyzed as cases where certain things are phenomenally present, but generically so.
Nothing is more obvious than the fact that we are able to experience, via perception, events in the world such a ball deflecting from the cross- bar of a goal. But what is the temporal relation between these two things, the event, and our perceptual experience of the event? One possibility is that the world progresses temporally through a sequence of instantaneous states — the striker’s foot in contact with the ball, then the ball between the striker and the goal, then the ball in contact with the cross-bar, and so forth —, while the perceiver’s experience is like - wise a sequence of perceptual experience states, each one of which corresponds to, or is a perception of, a corresponding state of the world — for example, a perception of the foot in contact with the ball, followed by a perception of the ball in the air, followed by a perception of the ball in contact with the cross-bar. This way of understanding the relationship between experience and the world is very natural, and nearly universal. However, it rests on two assumptions that can be brought into question. First, it assumes that at any time, the content of what is experienced is a temporally punctate state of the world. Second and relatedly, it assumes that the sequence of experience states temporally tracks the sequence of states of the world. The fact that we can perceive motion provides some reason to question the first assumption. Motion can only manifest over a temporal interval of non-punctate magnitude, so if we can perceive motion, then the temporal content of an experience cannot be limited to a temporally punctate instant. The existence of temporal illusions — cases where it seems as though A followed B even though in fact B followed A — provides some reason to question the second assumption. If the sequence of experience states just tracked the corresponding states of the world, then such illusions would not be possible. In this article, I will discuss both of these issues — the perception of motion and temporal illusions — in more detail. I will then outline an alternative way to understand the temporality of experience that denies both of the assumptions. That is, on this alternative proposal, the content of experience at any instant is not temporally punctate, but includes a temporal interval; and second, the details of what is experienced within this interval is not a mere passive reflection of the world’s temporality, but is the result of active interpretation. This alternative picture I call the trajectory estimation model.
The decades bracketing the end of the nineteenth century saw two colossal developments in the philosophy and psychology of the experience of time. The first was William James’ highly influential Principles of Psychology, published in 1890; the second was edmund Husserl’s Zur Phänomenologie des Inneren Zeitbewusstseins, based on notes written largely during the first decade of the twentieth century, but first published in 1928. Associated with each of these developments is a standard, largely unchallenged understanding of its historical precursors: James was chiefly synthesizing a good deal of work that had been done over the previous three decades or so in experimental psychology in Germany, primarily under the influence of Wundt, and framed this synthesis in terms of a philosophical idea he credited to “E. R. Clay,” namely, the specious present doctrine (henceforth, SP doctrine). Husserl was reacting to, and building on, attempts by Brentano and Meinong to provide analyses of time consciousness, and was also familiar with work in experimental psychology, including James’ work, and with the expression ‘specious present’ that James had used for the doctrine. But as we shall demonstrate in this paper, the standard picture is crucially incomplete. There is a clearly discernible line of philosophical debate about the temporality of experience which began with Thomas Reid, ran through a number of nineteenth-century Anglophone philosophers, and culminated in two independent termini: “E.R. Clay,” identified by James as the author of the anonymously published The Alternative: a Study in Psychology; and the work of the now nearly-completely forgotten Shadworth Hollway Hodgson. The first goal of this paper is discerning and describing this line of development and its two termini. Both of these termini were significant influences on James. The second goal of this paper is to argue that the second terminus, Hodgson, was also a significant and unappreciated influence on Husserl. Sections 2 through 5 discuss, in turn, the relevant doctrines of Thomas Reid, Dugald Stewart, Thomas Brown, and William Hamilton. Exposition of these authors establishes that discussion of the temporal character of perceptual experience was already underway prior to James, while tracing how distinct stances on relevant premises concerning consciousness and experience eventually led to the formulation of the SP doctrine. Section 6 discusses Robert Kelly (alias ‘E.R. Clay’) who named and (co-)developed the SP doctrine James made famous. Section 7 discusses Hodgson’s early work and his own independently-developed version of the specious present doctrine. Section 8 turns to Hodgson’s later work and the specific issue of his influence on Husserl. Section 9 concludes, and considers the reception of Hodgson and Kelly’s work.
This article outlines a unified information processing framework whose goal is to explain how the nervous system represents space, time, and objects. It explains the concept of the emulation theory of representation and describes an extension of the emulation framework for temporal representation. It discusses Alexandre Pouget's basis function model of spatial representation and describes how to combine the basis function model of spatial representation with the trajectory emulation model of temporal representation to yield an information processing framework that genuinely represents behavioral spatiotemporal trajectories of behavioral objects.
We taxonomize the varieties of representational reuse and point out that all the sorts of reuse that the brain engages in (1) involve something like a model (or schema or simulator), and (2) are effected in bodily and external media, as well as neural media. This suggests that the real fundamental organizational principle is not neural reuse, but model reuse.
An attempt is made to defend a general approach to the spatial content of perception, an approach according to which perception is imbued with spatial con- tent in virtue of certain kinds of connections between perceiving organism’s sensory input and its behavioral output. The most important aspect of the defense involves clearly distinguishing two kinds of perceptuo-behavioral skills—the formation of dis- positions, and a capacity for emulation. The former, the formation of dispositions, is argued to by the central pivot of spatial content. I provide a neural information processing interpretation of what these dispositions amount to, and describe how dis- positions, so understood, are an obvious implementation of Gareth Evans’ proposal on the topic. Furthermore, I describe what sorts of contribution are made by emula- tion mechanisms, and I also describe exactly how the emulation framework differs from similar but distinct notions with which it is often unhelpfully confused, such as sensorimotor contingencies and forward models.
Many forms of visual adaptation have been studied, including spatial displacements (Heuer & Hegele 2008), spatial inversions and rotations (Heuer & Rapp 2011), removing or enhancing various colors in the visual spectrum (Belmore & Shevell 2011; Kohler 1963), and even luminance inversion (Anstis 1992). But there have been no studies that have assessed adaptation to an inverted spectrum, or more generally color rotation. We present the results of an adaptation protocol on two subjects who wore LCD goggles that were driven by a video camera, but such that the visual scene presented to subjects was color-rotated by 120°, so that blue objects appeared green, green objects appeared red, and red objects appeared blue (with non-primary colors being analogously remapped). One subject wore the apparatus intermittently for several hours per day for a week. The second subject wore the apparatus continually for six days, meaning that all his visual input for those six days was color rotated. Several experiments were run to assess the kinds and degrees of adaptation, including Stroop (1935), the memory color effect (Hansen et al. 2006), and aesthetic judgments of food and people. Several additional phenomena were assessed and noticed, especially with respect to color constancy and phenomenal adaptation. The results were that color constancy initially was not present when colors were rotated, but both subjects adapted so that color constancy returned. However, there was no evidence of phenomenal color adaptation. Tomatoes continued to look blue, subjects did not adapt so that they started to look red again. We found no reliable Stroop result. But there was an adaptation to the memory color effect. Also, interesting differences were revealed in the way color affects aesthetic judgments of food versus people, and differences in adaptation to those effects.
Enaction, as put forward by Varela and defended by other thinkers (notably Alva Noë, 2004; Susan Hurley, 2006; and Kevin O’Regan, 1992), departs from traditional accounts that treat mental processes (like perception, reasoning, and action) as discrete, independent processes that are causally related in a sequen- tial fashion. According to the main claim of the enactive approach, which Thompson seems to fully endorse, perceptual awareness is taken to be a skill-based activity. Our perceptual contact with the world, according to the enactionists, is not mediated by representations but is enacted, and the notion of representation, belonging to the classic computational paradigm, has no place in this alternative approach. Though Thompson does not pronounce directly on the issue of representationalism, he is most definitely keeping the company of anti-representationalists, and in that context it is not unreasonable to take his silence for consent. In this paper, we will argue that the enactive approach to imagery is unworkable unless it makes appeal to representations, understood in a particular way. Not understood as pictures, to be sure. Or sentences for that matter. But those aren’t the only options.