A comparison of discrimination and identification of vibrotactile patterns

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The present study examined whether the locations of patterns on the skin affected the ability to process information about their shapes. In Experiment 1,pairs of spatial vibrotactile patterns, using the array from the Optacon, were presented sequentially to subjects' left index fingerpads, The location of each pattern in a pair was varied randomly among four locations on the skin. The subjects responded "same" or "different" on the basis of the shapes of patterns, regardless of their locations. Discrimination accuracy was highest and response time fastest when patterns occupied identical 10-cations (ILs), and performance suffered with increasing distance between patterns. In Experiment 2, pairs were presented to corresponding points or to noncorresponding points on separate fingerpads. When patterns occupied corresponding points on separate fingers, accuracy was lower than when patterns occupied ILs on a single finger, but higher than when patterns occupied noncorresponding points on separate fingers. The results suggested that discriminability declined partly because patterns did not occupy ILs,and partly because separate locations had different densities of innervation.

Section: Methodsmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 99%

The effect of location on the discrimination of spatial vibrotactile patterns

Horner

1995

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“…Only the main effects and interactions reaching at least the .05 level of significance are discussed here. There was a main effect of masker shape, showing that accuracy was lower in the presence ofDS than ofSS maskers [F(l,4) Many studies have shown that performance improves with increasing SOA when DS maskers are at SLoc (Cholewiak & Craig, 1984;Craig, 1976Craig, , 1978Craig, , 1982Craig, , 1983Craig, , 1985aCraig & Evans, 1987;Evans, 1987;Evans & Craig, 1986;Horner, 1991;Horner & Craig, 1989). Such improvement may be due to several factors, including a decline in temporal integration of target and masker features at longer SOAs (Evans, 1987;Evans & Craig, 1986) which would improve the clarity of individual features within the target.…”

Section: Resultsmentioning

confidence: 99%

“…asynchrony (SOA)-in order to examine the temporal The vibratory array measures 11.45 mm wide x 27.14 mm high characteristics of pattern processing (Cholewiak & and consists of 144 blunt pins arranged in 24 rows (1.18 mm sep- Craig, 1984;Craig, 1976Craig, , 1980Craig, , 1982Craig, , 1983Craig, , 1985a; Craig arating rows) and six columns (2.29 mm separating columns). & Evans, 1987;Evans, 1987;Evans & Craig, 1986; Each ofthe .25-mm-diameter pins vibrated at 230 Hz and at a comfortable intensity well above threshold, 33 V to the driver circuits, Horner, 1991;Horner & Craig, 1989). SOA was varied resulting in a maximum skin indentation of65 microns (Bliss et aI., in Experiment 1 to determine the extent to which the 10-1970;Bliss & Linvill, 1966).…”

Section: )mentioning

confidence: 99%

The effect of shape and location on temporal masking of spatial vibrotactile patterns

Horner

1997

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Target patterns presented to uncued locations on a single fingerpad were followed by either sameshape (SS) maskers or different-shape (DS) maskers presented to either the same location (SLoc) or a different location (DLoc). DS maskers interfered with identification more when they were at SLoc than when they were at DLoc,but the reverse was true for SS maskers; they interfered more at DLoc than at SLoc. Whentargets were presented to cued locations, performance in the absence of maskers improved, but the pattern of interference from maskers resembled that for uncued presentation. The proportion of masker responses on incorrect trials revealed that both temporal masking and response competition may be involved in the effects of location on pattern identification.The present study examined whether the location of a pattern on the skin affects the ability to process information about its spatial features. Specifically, does location affect the ability to identify spatial patterns on a single fingerpad? The fingerpad was examined because of its high spatial resolution (Sathian & Zangaledze, 1996;Sherrick & Cholewiak, 1986;Stevens & Patterson, 1995;Van Boven & Johnson, 1994;Weinstein, 1968), because of its role in tactual exploration, and because it is used to process successive spatial patterns in tactile communication systems such as braille and the Optacon (Bliss, Katcher, Rogers, & Shepard, 1970). In studies using the Optacon vibratory array or similar dense arrays of vibrators, spatial patterns have usually been presented either to a single location or to locations on separate body sites. Some of the studies examining separate body sites have compared the pattern processing capabilities of the sites (Cholewiak & Craig, 1984;Craig, 1977;Loomis, 1980;Scadden, 1973). In other studies examining separate sites, patterns were presented to separate fingers and attentional factors were investigated (Craig, 1985a;Craig & Evans, 1995;Evans & Craig, 1991, 1992Evans, Craig, & Rinker, 1992;Horner, 1992Horner, , 1995Rinker & Craig, 1994). Relatively few studies have examined how spatial patterns are processed at adjacent locations on a single fingerpad.Hill (1974) indirectly measured the effects of presenting patterns to adjacent locations on the fingerpad when An earlier version of some of the material in Experiment I was presented at the annual meeting of the Psychonomic Society in November 1993. An earlier version of some of the material in Experiment 2 was presented at the annual meeting of the American Psychological Society in June 1995. This research was supported by the University of Wisconsin, Oshkosh, and by Grant DC-00095 from the Nationallnstitutes of Health. nT.H. wishes to thank James Craig for his comments on earlier versions of this manuscript and Roger Rhodes for his assistance in conducting these experiments. Correspondence should be addressed to D. T. Horner, Psychology Department, University of Wisconsin, Oshkosh, WI 54901-8601 (e-mail: homer@vaxa.cis.uwosh.edu).he examined Optacon reading rates using differ...

“…They found differences between sites in the absolute levels of performance for both tasks, but in opposite directions. Specifically, observers were able to learn to identify the patterns far better when the patterns were presented to the finger than to the thigh, yet discrimination performance was superior on the thigh, illustrating a dissociation between the two tasks (see also Horner, 1991;Horner & Craig, 1989). The discrimination data, however, did suggest that there is a functional similarity in processing across sites (i.e., the shape of the curve describing the relationship of performance to stimulus onset asynchrony was the same for both sites).…”

mentioning

confidence: 99%

Vibrotactile pattern discrimination and communality at several body sites

Cholewiak

Collins

1995

In a series of experiments, the effects of spatial layout on vibrotactile pattern perception were explored by testing the ability to discriminate between two sequentially presented patterns that share active elements in the same spatial locations. Two-dimensional displays were used in order to examine the functional relationship between discrimination performance and pattern communality, defined as the sharing elements, on different body sites. Accuracy of discrimination judgments was inversely proportional to communality, regardless of the number of pattern elements. For compact arrays fitted to the finger, palm, and thigh, the effects of communality appeared equivalent. The similarity between finger and thigh functions is remarkable, considering the dramatic differences between these sites in receptor components and structure. Whenthese data were compared with those from arrays with distributed contactors, performance was substantially better with well-separated pattern elements, Such findings help to explicate how information from apposed patterns can best be delivered to the skin through tactile communication systems,