Perceptual Representation

The first thing that someone actively involved in labeling policy, design, education or research must realize is that the objective label shown to consumers or workers so as to affect their behavior is not necessarily the label they perceive. The external sensory stimuli of the label—e.g., shape, color, design, size—are cognitively organized by the reader as representations of these exter- 

Obtaining reliable information about a label, the degree of identity between the objective label and the reader s perceptions and representation of the label, and the behavior elicited by the perceived label requires research and careful observation, and these will be discussed in later sections. 

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THE INFLUENCE OF EMOTIONS ON THE PERSISTENCE OF CONSCIOUS PERCEPTUAL REPRESENTATIONS... 

Ellis, 1992] Ellis, D. (1992). A perceptual representation of sound. Master s thesis, Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology. 

Ellis et al., 1991] Ellis, D., Vercoe, B.,, and Quatieri, T. (1991). A perceptual representation of audio for co-channel source separation. In Proc. IEEE Workshop Appl. of Signal Processing to Audio and Acoustics, Mohonk Mountain House, New Paltz, NY. 

The distinction is ontologically important, especially for the question of metaphysical naturalism or materialism and also for epistemology. For actual sense-data are merely phenomenal, immaterial objects moreover, they are objects of consciousness, of acquaintance, and (on some accounts) of sensing itself. By contrast, mere perceptual representations can be physical, neurophysiological items, and they need not themselves be objects of consciousness, acquaintance, or (certainly) sensing. 

In the present chapter I use representationalism as a name for the view that awareness of qualitative properties constitutively involves experiential or perceptual representations. But there is also a more inclusive sense of the term — a sense in which it is true to say that representationalism stands for any view that claims that awareness of qualitative properties involves representations. On this more inclusive sense, it is not required that the relevant representations be experiential in character. Now, beliefs and judgments are representational states, though the representations from which they are constructed are conceptual rather than experiential. Accordingly, since the third proposal claims that introspective awareness of qualitative states involves beliefs or judgments, it counts as a form of representationalism, when the term is used with its more inclusive sense. I emphasize, however, that it does not count as a form of representationalism when the term is used in the sense that is operative in the present paper. 

For me, nothing illustrates this chasm between observation and chemical theory better than my experiences as a teaching assistant in the laboratory of a beginning chemistry course. Students were carefully following procedures described in the lab manuals, filling in the blanks to describe their observations. Then as a kind of climax they were asked to Write the equation for this reaction. Students were often stunned by this request, for they could perceive no connection between what they had observed and the equation they were expected to write. This gap between the perceptual experience of events and their conceptual representation is wider and deeper than for any other of the basic sciences. That fact in large part accounts for the late arrival of chemistry at its maturity, with the work of John Dalton early in the nineteenth century. 

Before introducing the method for calculating the internal representation the psychoacoustic fundamentals of the perceptual model is explained in the next chapter. 

Figure 1.7 Overview of the basic transformations which are used in the development of the PAQM (Perceptual Audio Quality Measure). The signals x(t) and y t) are windowed with a window w(t) and then transformed to the frequency domain. The power spectra as function of time and frequency, Px (t, f) and Py(t, /) are transformed to power spectra as function of time and pitch, px(t, z) and py(t, z) which are convolved with the smearing function resulting in the excitations as a function of pitch Ex (/, z) ar 6Ey(t, z). After transformation with the compression function we get the internal representations x(f, z)and ,(, z) from which the average noise disturbance Cn over the audio fragment can be calculated.

For a large class of signals, therefore, the sine-wave analysis/synthesis is nearly a perceptual identity system and the signals are expressed in terms of a functional model describing the behavior of each of its sine-wave components. The sine-wave representation therefore provides an appropriate framework for developing signal modification and enhancement techniques based on transforming each of the functional descriptors. 

Beerends and Stemerdink, 1994b] Beerends, J. G. and Stemerdink, J. A. (1994b). A perceptual speech quality measure based on a psychoacoustic sound representation. J. Audio Eng. Soc., 42(3) 115-123. 

The perceptual model as developed in this chapter is used to map the input and output of the audio device onto internal representations that are as close as possible to the internal representations used by the subject to judge the quality of the audio device. It is shown that the difference in internal representation can form the basis of a perceptual audio quality measure (PAQM) that has a high correlation with the subjectively perceived audio quality. Furthermore it is shown that with a simple cognitive module that interprets the difference in internal representation the correlation between objective and subjective results is always above 0.9 for both wideband music and telephone-band speech signals. For the measurement of the quality of telephone-band speech codecs a simplified version of the PAQM, the perceptual speech quality measure (PSQM), is presented. 

In the internal representation approach the quality of an audio device is measured by mapping the reference and output of the device from the physical signal representation (measured in dB, seconds, Hertz) onto a psychoacoustic (internal) representation (measured in compressed Sone, seconds, Bark). From the difference in internal representation the perceptual audio quality measure (PAQM) can be calculated which shows good correlation with the subjectively perceived audio quality. 

Unlike iconicity and associations, mappings of conceptual and spatial schemas based on polarity do not rely on perceptual resemblance, nor on previously experienced pairings between attributes and objects. Instead, polarity is based on the organizational structure underlying many perceptual and conceptual dimensions. Polarity constrains mappings of spatial and conceptual schemas when a spatial representation shares oppositional structure or directionality of dimension with the concept being represented. A simple way to envision this oppositional structure is as a continuum with asymmetrically weighted ends. 

What Smith and Sera s (1992) results show us is that not all matching of representations is based on associations acquired through experience. The finding that very young children paired mice according to perceptual... 

Iconicity constrains mapping when the spatial representation maintains some perceptual characteristics of the object or set of objects it represents. Associations constrain mapping when the spatial representation shares some properties with the object or concept being represented. 

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