Active engagement of the intact hand may be critical for therapies seeking to stimulate the former hand territory.

This article examines the relation between changing categorization decision rules and the nature of the underlying perceptual representation. Observers completed a matching task that required them to adjust the length and orientation of a single line stimulus until they perceived it to "match" a second line stimulus (Alfonso-Reese, 1996. The same observers then completed four categorization tasks with the same stimuli. Data from the matching task were used to estimate a perceptual representation for each stimulus and observer. Three hypotheses regarding potential interactions between categorization decision rules and perceptual representation were examined. One assumed that there was no interaction between decision rules and perceptual representation. The second assumed that linear categorization rules affect the perceptual representation differently from nonlinear categorization rules. The third assumed that dimensional integration rules affected the perceptual representation differently from decision rules that require the observer to set a criterion along one stimulus dimension while ignoring the other; this is referred to as decisional selective attention. The results suggested that (l) the matching task perceptual representation provided a good account of the categorization data, (2) decisional selective attention affected the perceptual representation differently from decisional integration, and (3) decisional selective attention generally decreased the perceptual variability along the attended dimension.Categorization is a primary component of many behaviors ofall organisms (Alcock, 1989). In general, each category exemplar can be decomposed into a set of values along multiple basic stimulus dimensions, each of which is continuous rather than binary valued (e.g., Ashby, 1992a;. For example, category exemplars may vary along the dimensions of size, length, orientation, color, location, frequency, and amplitude. Because each dimension is processed differently by the perceptual system, it is important to understand the nature of the perceptual representation and how it affects categorization performance (Alfonso- Reese, 1997;Ashby & Lee, 1991;Nosofsky, 1986). Conversely, recent research suggests that the act of categorization might alter the structure of the perceptual representation (e.g., Ashby & Lee, 1991;Goldstone, 1994;Nosofsky, 1986). In particular, different categorization rules might alter the structure of the perceptual representation in different ways. This article addresses both of these issues within a single exThis research was supported in part by National Science Foundation Grant SBR-9796206 and NIH Grant ROI MH59196. We thank Helena Kadlec, Robin Thomas, and an anonymous reviewer for helpful comments on an earlier draft ofthis manuscript. We also thank Greg Ashby, Leslie Cohen, Randy Diehl, Bill Geisler, David Gilden, Art Markman, and Tom Thornton for discussions that influenced this work. Correspondence should be addressed to W. T. Maddox, Department of Psychology, Mezes Hall 330, Universit...

Summary Amputation induces substantial reorganization of the hand map in primary sensory cortex (S1 complex, hereafter S1) [1, 2], and these effects of deafferentiation increase with time [3]. Determining whether these changes are reversible is critical for understanding the potential to recover from deafferenting injuries. Earlier BOLD fMRI data demonstrate increased S1 activity in response to stimulation of an allogenically transplanted hand [4]. Here, we report the first evidence that the representation of a transplanted hand can actually recapture the pre-amputation S1 hand territory. A 54 year-old male received a unilateral hand transplant 35 years after traumatic amputation of his right hand. Despite limited sensation, palmar tactile stimulation delivered four months post-transplant evoked contralateral S1 responses that were indistinguishable in location and amplitude from those detected in healthy matched controls. Although commonly reported in amputees [5, 6], we find no evidence for persistent intrusion of representations of the face within the representation of the transplanted hand. Our results suggest that even after decades after complete deafferentiation, restoring afferent input to S1 leads to re-establishment of the gross hand representation within its original territory. Unexpectedly, large ipsilateral S1 responses accompanied sensory stimulation of the patient’s intact hand. These may reflect a change in interhemispheric inhibition that could contribute to maintaining latent hand representations during the period of amputation.

A noninvasive method for accurately measuring anticipatory coarticulation at experimentally defined temporal locations is introduced. The method leverages work in audiovisual (AV) speech perception to provide a synthetic and robust measure that can be used to inform psycholinguistic theory. In this validation study, speakers were audio-video recorded while producing simple subject-verb-object sentences with contrasting object noun rhymes. Coarticulatory resistance of target noun onsets was manipulated as was metrical context for the determiner that modified the noun. Individual sentences were then gated from the verb to sentence end at segmental landmarks. These stimuli were presented to perceivers who were tasked with guessing the sentence-final rhyme. An audio-only condition was included to estimate the contribution of visual information to perceivers' performance. Findings were that perceivers accurately identified rhymes earlier in the AV condition than in the audio-only condition (i.e., at determiner onset vs determiner vowel). Effects of coarticulatory resistance and metrical context were similar across conditions and consistent with previous work on coarticulation. These findings were further validated with acoustic measurement of the determiner vowel and a cumulative video-based measure of perioral movement. Overall, gated AV speech perception can be used to test specific hypotheses regarding coarticulatory scope and strength in running speech. V

The goal of the present work was to develop a sensitive, non-invasive method for accurately assessing the temporal scope of coarticulation in speech production. Building on work in audiovisual speech perception (Munhall and Tohkura, 1998; Moradi et al., 2013), we used a gating paradigm and human judges to identify the temporal onset of anticipatory lip rounding in simple SVO sentences produced by five adult females. The sentences were gated based on acoustic landmarks from the midpoint of the verb through to the midpoint of the object noun. Full sentences were also included. Judges were asked to decide whether the object noun rhymed with rounded “oop” or unrounded “ack.” Results indicated an earlier correct identification of rounding in the audiovisual condition compared to the control, audio-only condition. The audiovisual judgments also provided greater temporal specificity regarding the onset of coarticulation than could obtained with acoustic measurement or with a video-based kinematic measure. Insofar as human judges appear to anticipate and even benefit from head movement in audiovisual speech tasks (Munhall et al., 2004), our method should prove especially useful for measuring the temporal extent of coarticulation in younger, more rambunctious speakers.