Talk:Categorical perception

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Stevan Harnad is the expert, but as a former graduate student studying this area, I am somewhat familar with the theory, so I would like to recommend the following points. I think the aricle would be improved if it was written to include these additional points from the seminal research. It may make it slightly more complicated, but I think these points are important to capture the spirit of the original research and theory.

- The ubiquitous relationship between discrimination and identification found in the early, seminal studies: discrimination is no better than absolute identification. This is not included anywhere in this article, is it? Please correct me if I am wrong, but this distinction formed the basis for the definition of categorical perception. If a graph of the classic "inverted V" discrimination function was added, I think that could help explain the fundamental concept considerably.

• I don't understand your point. Discrimination is a relative judgments, such as same/different (for a pair of inputs). Identification is an absolute judgement, usually category-naming (for a single input). CP is defined as the discrimination function (peaks and troughs in discriminability) following the identification function (category boundaries): If its harder to discriminate differences between shades of green and shades of blue than differences between blue and green (when the size of the differences in log-frequency are equal) then you have a CP effect. The "inverted V" (peak) in the discriminability function is as at the category boundary for the blue/green identification function. Now the article n CP already says all of this: what do you want added? --Stevan Harnad

- Alternative accounts to CP; Researchers such as Dominic W. Massaro have pointed out for years that researchers have failed to consider alternative mathematical models that can account for categorical perception. The research in this area has consistently shown predicted discrimination based on identification nearly always underestimates observed discrimination. Massaro has shown that models of continuous perception predict observed discrimination better relative to categorical models when the root mean-squared deviation (RMSD) between observed and predicted values is used as a goodness-of-fit metric. Massaro has argued perception is essentially continuous - the perceptual system can discriminate within category - but the nature of the task participants have been given forces a categorical response. I think including this is important in an encyclopedia article of CP.

• CP never implied that there was no discriminability within a category. (Shades of blue do not all look identical: we can discriminate them. We just can't discriminate the as well as we can discriminate the same sized difference when it crosses the blue-green boundary. So what point of Massaro's do you think needs to be added? (I do think, though, that the CP article could be usefully updated to add the more recent findings on CP and neural imagery studies, as well as some of the animal studies on plasticity and learning. --Stevan Harnad

—The preceding unsigned comment was added by SdlV (talk • contribs) 23:24, 23 June 2006 (UTC)

"Reliabile sources"

Just a reminder to the authors of this article about what Wikipedia deems so-called "reliable sources." "Wikipedia articles should be based on reliable secondary sources. This means that while primary or tertiary sources can be used to support specific statements, the bulk of the article should rely on secondary sources." See this also. Not that I believe there are problems with the article's factual accuracy, just that the references section seems to violate Wikipedia policies. RobertM525 (talk) 19:56, 18 May 2009 (UTC)

"Is this Accurate?"

I'm not sure of the accuracy of this article. I've been studying categorical perception in speech perception for 10 years, and the consensus in speech seems to be that something closer to Massaro or Pisoni's views are right. The evidence for CP comes from heavily biased tasks that were used in the 1970s. When replicated with more sensitive psychophysical measures of discrimination (Carney, Widen & Viemeister, 1977; Gerrits & Schouten, 2004; Schouten, Gerrits & Van Hessen, 2003), with goodness-ratings tasks (Massaro & Cohen, 1983), and with eye-tracking (McMurray, Aslin, Tanenhaus, Spivey & Subik, 2008), there does not appear to be any evidence for categorical perception, and speech perception appears quite continuous. Moroever, even under the biased tasks, it seems only operative with some speech contrasts, vowels (Fry, Abramson, Eimas & Liberman, 1962) and to a lesser extent, fricatives (Healy & Repp, 1982) have never been found to be percieved categorically.

This seems to be something that the rest of cognitive science has never noticed (hence the proliferation of CPT studies well after this was discovered), so I can understand the error. But, unfortunately, I don't have the time to write a properly sourced article to correct this serious deficiency in this article. Someone should! Thebobmc (talk) 20:53, 6 July 2009 (UTC)

A "Criticism" section would be good, as well.201.21.68.17 (talk) 05:49, 2 May 2010 (UTC)

I have only one thing that I think needs to be made clear about this article: with the exception of the first intro paragraph it is virtually or perhaps entirely an exact copy of the article on "Categorical Perception" in Encyclopedia of Cog. Sciences. Ed. L. Nadel. True, a note at the bottom does state: "This article is based on material from the article Categorical Perception in the Encyclopedia of Cognitive Science, used here with permission of the author, S. Harnad." But nevertheless this needs to be made clear. I'm not an expert (no do I want to be one) on these matters but perhaps further verification with the publisher about the legitimacy of the (Nature Publishing) use and the identity of the author (Stevan Harnad) is needed. I say this because the article is not just based on the original but is a copy of the original (with very minor exception)and this is not made clear. ```` — Preceding unsigned comment added by 76.70.105.87 (talk) 21:14, 8 September 2012 (UTC)

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