Online research in philosophy

Dreyfus enlists the aid of Merleau-Ponty in his critique of representationalist theories of cognition. Such theories posit a representational element at some level of cognitive activity. The nature of the representation and how we think of it will depend upon the level at which one claims to find it. If we consider the case of perception, at one extreme it might be claimed that the representation is a conscious one, that is, that the perceiving subject is conscious of a representation, a _Vorstellung_ in the Kantian sense. In this case, it would clearly come between the perceiving subject and the world and in that sense interfere with a direct perception of the world. This sort of representational theory would be equivalent to idealism, and for good phenomenological reasons it is rejected by Merleau-Ponty and Dreyfus. At the other extreme, it is possible to find cognitive scientists talking about representations at the level of brain activity. Neural representations, either firing patterns or the actual "hard wiring" of neuronal connections (as, for example, neural maps in the somatosensory and motor areas responsible for the experience of the subject's own body), in some way enable perception. At this level of description there are various debates about how these mechanisms can be called representational. If the concept of representation involves reference to the perceptual field, in what sense does a neuronal pattern refer? There are also the familiar debates about how such mechanisms actually function, as well as the difficult problem of how such functions actually translate into personal level experience. Before these debates get off the ground, however, Dreyfus wants to steal the ammunition. He denies that there are representations at the level of brain processes.

The phenomenal character of perceptual experience involves the representation of colour, shape and motion. Does it also involve the representation of high-level categories? Is the recognition of a tomato as a tomato contained within perceptual phenomenality? Proponents of a conservative view of the reach of phenomenal content say 'No', whereas those who take a liberal view of perceptual phenomenality say 'Yes'. I clarify the debate between conservatives and liberals, and argue in favour of the liberal view that high-level content can directly inform the phenomenal character of perception.

Summary. The viability of the proposal that human cognition involves the utilization of nonsentential models is seriously undercut by the fact that no one has yet given a satisfactory account of how neurophysiological circuitry might realize representations of the right sort. Such an account is offered up here, the general idea behind which is that high-level models can be realized by lower—level computations and, in turn, by neural machinations. It is shown that this account can be usefully applied to deal with problems in fields ranging from artificial intelligence to the philosophy of science.

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High-level theory is the view that high-level properties—the property of being a dog, being a tiger, being an apple, being a pair of lips, etc.—can be represented in perceptual experience. Low-level theory denies this and claims that high-level properties are only represented at the level of perceptual judgment and are products of cognitive interpretation of low- level sensory information (color, shape, illumination). This paper discusses previous attempts to establish high-level theory, their weaknesses, and an argument for high-level theory that does not have these weaknesses.

In this paper I argue that because Churchland does not adequately address the distinction between high-level cognitive theories and low-level embodied theories, Churchland's claims for theory-laden perception lose their epistemological significance. I propose that Churchland and others debating the theory-ladenness of perception should distinguish carefully between two main ways in which perception is plastic: through modifying our high-level theories directly and through modifying our low-level theories using training experiences. This will require them to attend to two very different types of constraints on the modification of our perceptions.

There has been a long-standing debate between symbolicists and connectionists concerning the nature of representation used by human cognizers. In general, symbolicist commitments have allowed them to provide superior models of high-level cognitive function. In contrast, connectionist distributed representations are preferred for providing a description of low-level cognition. The development of Holographic Reduced Representations (HRRs) has opened the possibility of one representational medium unifying both low-level and high-level descriptions of cognition. This paper describes the relative strengths and weaknesses of symbolic and distributed representations. HRRs are shown to capture the important strengths of both types of representation. These properties of HRRs allow a rebuttal of Fodor and McLaughlin's (1990) criticism that distributed representations are not adequately structure sensitive to provide a full account of human cognition.

Theories that make action central to perception are plausible, though largely untried, for space perception. However, explaining object recognition, and high-level perception generally, will require reference to representations of the world in some form. Nonetheless, action is central to cognition, and explaining high-level perception will be aided by integrating an understanding of action with other aspects of perception.

E-Z Reader 7 is a processing model of eye-movement control. One constraint imposed on the model is that high-level cognitive processes do not influence eye movements unless normal reading processes are disturbed. I suggest that this constraint is unnecessary, and that the model provides a sensible architecture for explaining how both low- and high-level processes influence eye movements.