this article should be addressed to Robert Goldstone, Psychology Department, Indiana University, Bloomington, Indiana 47405. Electronic mail may be sent to rgoldsto @ ucs.indiana.edu

This paper reviews four conceptions of the nature of sensory feedback mechanisms mediating voluntary performance, including serial chaining, This report was supported in part by National Science Foundation Grant GS-1601 to the Ohio State University, administered by the author. The author is grateful to D. E. Berlyne, A. E. Goss, and A.M. Liberman for commenting on portions of an earlier draft. 2 Requests for reprints should be sent to Anthony G. Greenwald, Department of Psychology, Ohio State University, 404C West 17th Avenue, Columbus, Ohio 43210. closed-loop, and fractional anticipatory goal response mechanisms, and gives particular attention to a reformulation of the principle of ideo-motor action. At the outset, certain boundaries of the present treatment should be marked off. First, verbal mediating mechanisms and the related topics of meaning and meaningfulhess will not be given detailed coverage since it would expand this paper greatly, and perhaps unnecessarily, to attempt to do justice to the literature on verbal mediation. A number of influential writers (Goss, 1961; Luria, 1961; Miller & Dollard, 1941; Osgood, 1957; Paw lov, 1955) have assumed, as is assumed here, that verbal mediators of skilled performance differ from nonverbal mediators primarily in that the former operate at higher levels of performance organization. Accordingly, a 73 74 ANTI{ONY G. GREENWALD later section of this paper briefly treats the application to verbal behavior of principles developed herein regarding nonverbal sensory feedback mediating mechanisms. Second, since the present focus will be on mediation processes in performance of learned skills, data and theorization concerning me- diation in classical conditioning and concerning innately organized skills will not be considered...

The authors report a series of studies designed to determine whether effects similar to those observed in the innate categorical perception of color and phonemes are induced during the learning of simple unidimensional categories and more complex multidimensional ones. In Experiment 1 no evidence was found for such effects when stimuli varied on 1 dimension. Experiments 2 and 3 demonstrated a within-category compression effect but no between-category expansion effect for stimuli varying in 2 dimensions. Compression only was also shown in Experiment 4, which used pictures of actual objects. Multidimensional scaling analyses illustrate how within-category compression without expansion was sut~cient to produce categorical clustering of items in the similarity space. These analyses also show that learning changed the dimensional structure of similarity space. Results are compared with those from other studies exploring similar phenomena and with neural network simulations. Most contemporary models of category learning rely to

Five experiments explored the question of whether new perceptual units can be developed if they are diagnostic for a category learning task, and if so, what are the constraints on this unitization process? During category learning, participants were required to attend either a single component or a conjunction of five components to correctly categorize an object. Evidence consistent with unitization was found in that the conjunctive task became much easier with practice, and this improvement was not found for the single component task, or for conjunctive tasks in which the components could not be unitized. Influences of

Psychophysical phenomena such as categorical perception and the perceptual magnet effect indicate that our auditory perceptual spaces are warped for some stimuli. This paper investigates the effects of two different kinds of training on auditory perceptual space. It is first shown that categorization training using non-speech stimuli, in which subjects learn to identify stimuli within a particular frequency range as members of the same category, can lead to a decrease in sensitivity to stimuli in that category. This phenomenon is an example of acquired similarity and apparently has not been previously demonstrated for a category -relevant dimension. Discrimination training with the same set of stimuli was shown to have the opposite effect: subjects became more sensitive to differences in the stimuli presented during training. Further experiments investigated some of the conditions that are necessary to generate the acquired similarity found in the first experiment. The results of these...

Functional magnetic resonance imaging (fMRI) was used to investigate the representation of sound categories in human auditory cortex. Experiment 1 investigated the representation of prototypical (good) and non-prototypical (bad) examples of a vowel sound. Listening to prototypical examples of a vowel resulted in less auditory cortical activation than listening to non-prototypical examples. Experiments 2 and 3 investigated the effects of categorization training and discrimination training with novel non-speech sounds on auditory cortical representations. The two training tasks were shown to have opposite effects on the auditory cortical representation of sounds experienced during training: discrimination training led to an increase in the amount of activation caused by the training stimuli, whereas categorization training led to decreased activation. These results indicate that the brain efficiently shifts neural resources away from regions of acoustic space where discrimination between sounds is not behaviorally important (e.g., near the center of a sound category) and toward regions where accurate discrimination is needed. The results also provide a straightforward neural account of learned aspects of perceptual distortion near sound categories: sounds from the center of a

We report simulations with backpropagation networks trained to discriminate and then categorize a set of stimuli.

Recently, speech researchers have begun to examine the formation of speech sound (phonetic) categories and to analyze the internal structure of the consequent categories. One of the most prominent products of this subfield has been the Perceptual Magnet Effect (PME) and the attendant Native Language Magnet (NLM) theory of Kuhl (1991, 2000). In the present paper, a critical review of the evidence for NLM is offered. Because of concerns about the nature of the stimuli, possible confounds inherent in the empirical procedures and failed replications, it is concluded that there is little positive evidence supporting NLM. However, the goal of uncovering the structures of phonetic categories and mechanisms responsible for those structures remains central to an understanding of language acquisition and speech perception more generally. Data from several empirical paradigms investigating the formation and structure of complex auditory categories are beginning to form a coherent picture of phonetic category acquisition.