Online research in philosophy

Hommel et al. propose that high-level perception and action planning share a common representational domain, which facilitates the control of intentional actions. On the surface, this point of view appears quite different from an alternative account that suggests that “action” and “perception” are functionally and neurologically dissociable processes. But it is difficult to reconcile these apparently different perspectives, because Hommel et al. do not clearly specify what they mean by “perception” and “action planning.” With respect to the visual control of action, a distinction must be made between conscious visual perception and unconscious visuomotor processing. Hommel et al. must also distinguish between the what and how aspects of action planning, that is, planning what to do versus planning how to do it.

Recent work in visual perception shows that its phenomenal and cognitive aspects cannot be distinguished sharply. A preferable treatment of visual perception is to describe perceptual strategies, which represent the various ways in which perceivers may focus interest, and which are treated in this paper by two examples. Perceptual strategies suggest that both Sense Data theories, on the one hand, and treatments of perception such as Hanson's, on the other, are over-simplified. This work further suggests that the traditional distinction between primary and secondary qualities should be replaced by an epistemological distinction between visual and physical qualities. Such a distinction clarifies epistemological investigations of perception and shows the relevance of experimental investigations of visual perception to epistemological problems.

Marr (1982) may have been one of the first vision researchers to insist that in modeling vision it is important to separate the location of visual features from their type. He argued that in early stages of visual processing there must be “place tokens” that enable subsequent stages of the visual system to treat locations independent of what specific feature type was at that location. Thus, in certain respects a collinear array of diverse features could still be perceived as a line, and under certain conditions could function as such in perceptual phenomena like the Poggendorf illusion.

Recent developments in vision science have resulted in several major changes in our understanding of human visual perception. For example, attention no longer appears necessary for "visual intelligence"--a large amount of sophisticated processing can be done without it. Scene perception no longer appears to involve static, general-purpose descriptions, but instead may involve dynamic representations whose content depends on the individual and the task. And vision itself no longer appears to be limited to the production of a conscious "picture"--it may also guide processes outside the conscious awareness of the observer.

Boundary completion and surface filling-in are computationally complementary processes whose multiple processing stages form processing streams that realize a hierarchical resolution of uncertainty. Such complementarity and uncertainty principles provide a new foundation for philosophical discussions about visual perception, and lead to neural explanations of difficult perceptual data.

Fodor argues that speech perception is accomplished by a module. Typically, modular processing is taken to be bottom-up processing. Yet there is ubiquitous empirical evidence that speech perception is influenced by top-down processing. Fodor attempts to resolve this conflict by denying that modular processing must be exclusively bottom-up. It is argued, however, that Fodor's attempt to reconcile top-down and modular processing fails, because: (i) it undermines Fodor's own conception of modular processing; and (ii) it cannot account for the contextually varying top-down influences that characterize speech perception.

Clearly we can perceive both objects, and various aspects or appearances of those objects. But how should that complexity of perceptual content be explained or analyzed? I argue that perceptual representations normally have a double or two level nested structure of content, so as to adequately incorporate information both about contextual aspects Y(X) of an object X, and about the object X itself. On this double content (DC) view, perceptual processing starts with aspectual data Y?(X?) as a higher level of content, which data does not itself provide lower level X-related content, but only an aspectually encoded form of such data. Hence the relevant perceptual data Y?(X?) must be.

Natural language processing involves a tight coupling between action (the production of language) and perception (the comprehension of language). We argue that similar theoretical principles apply to language processing as to action/perception in general. Language production is not driven solely by the speaker's intentions; language comprehension is not only input-driven; production and perception use common representations. We will relate recent findings from our language production lab to the Theory of Event Coding (TEC)'s principle of feature binding.

In this paper I argue for the cognitive impenetrability of perception by undermining the argument from reentrant pathways. To do that I will adduce psychological and neuropsychological evidence showing that (a) early vision processing is not affected by our knowledge about specific objects and events, and (b) that the role of the descending pathways is to enable the early-vision processing modules to participate in higher-level visual or cognitive functions. My thesis is that a part of observation, which I will call perception, is bottom-up and theory neutral. As such, perception could play the role of common ground on which a naturalized epistemology can be built and relativism avoided.

Whenever knowledge of the possible interpretation or conceptualization of some- thing helps in perceiving that thing, we say the processing is conceptually driven. That is, the process starts with conceptualization of what might be present and then looks for confirming evidence, biasing the processing mechanisms to give the expected result... Conceptually driven processing and data-driven processing almost always occur together, with each direction of processing contributing something to the total analysis. (Lindsay and Norman 1977, p. 13).