Effect of Stimulus-Change Method on Tactile-Image Recognition

Beauchamp, Kenneth L.; Matheson, Douglas W.; Scadden, Lawrence A.

doi:10.2466/pms.1971.33.3f.1067

Cited by 16 publications

(11 citation statements)

References 3 publications

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“…This follows because phase information in the lower spatial frequencies, varying as a function of time, would carry the identity of the letter. That sequential tracing of a letter does lead to higher recognition accuracy than full-field presentation has been shown with the TVSS (Beauchamp, Matheson, & Scadden, 1971). This can also be demonstrated with the visual sense by observing letters through a low-pass spatial filter (e.g., a strong spherical lens or a diffusing screen) that are presented either full field or sequentially, as when traced by a moving point of light.…”

Section: Idvin8 Slit Stationary Lettermentioning

confidence: 79%

Tactile letter recognition under different modes of stimulus presentation

Loomis

1974

Perception & Psychophysics

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Block capital letters were displayed to experienced and inexperienced Ss, using a 20 x 20 matrix of vibratory tactors placed against the back. In two separate experiments, a total of five modes of stimulus presentation, three of them employing a linear scanning slit, were studied. The poorest method, stationary flashing of the letter, allows performance that is well above chance, implying that a purely spatial presentation does convey information. Performance is improved when the letter is moved horizontally across the display. The best performance is achieved when the amount of simultaneous stimulation is limited by using a linear scanning slit. In one method, the letter moves behind a stationary slit, with the result that its horizontal dimension is portrayed only in time. In the other two methods, the scanning slit moves across the stationary letter, portraying the letter both in time and in space. The results of all five display modes indicate that Ss can use whichever representation, spatial or temporal, is available, although patternings which most closely approximate sequential tracing by a single moving point lead to the highest recognition accuracy. We interpret these results in terms of the limited spatial resolution of the cutaneous sense. While the perception of a letter presented in either full-field condition is limited by the spatial resolution, the best measure being the two-point limen, the perception of a letter traced sequentially is limited by the localization acuity of the cutaneous sense, the best measure being the "error of localization," which is known to be considerably smaller than the two-point limen. Inasmuch as the slit methods of presentation are a compromise between simultaneous and sequential display, letter-recognition accuracy is better with slit presentation than with the corresponding full-field mode of display.Because the skin, like the retina, is a spatially extended receptive surface, it has more than once been considered as an alternative channel for transmitting spatial patterns which might otherwise be handled by the visual system. The qustion that arises is how to display spatial patterns on the skin to best exploit its processing capabilities. We are all familiar with "finger writing" on the back as a way of communicating patterns; although moving a single point in time and space permits high recognition .accuracy for simple patterns, it suffers from the disadvantages of burdening the observer's memory and requiring fairly elaborate preprocessing when used with a video input.

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Section: Idvin8 Slit Stationary Lettermentioning

confidence: 79%

Tactile letter recognition under different modes of stimulus presentation

Loomis

1974

Perception & Psychophysics

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“…This mode is identical to the CS mode except that each element of the letter is turned off before the next element comes on. Preliminary measurements had indicated that the OS mode produced poorer performance than the CS mode; however, the OS bears a greater similarity to the mode tested by Beauchamp, Matheson, and Scadden (1971), and thus, it was felt, should be tested formally. The St mode was tested at 4.3, 26, 100, and 400 msec, the Sc mode at 26, 100, and 400 msec, the CS mode at…”

Section: Methodsmentioning

confidence: 99%

“…Loomis predicted that very good performance would be obtained tactually by a sequential presentation of a pattern, a mode similar to the children's game of backwriting. Such a mode was found, by Beauchamp, Matheson, and Scadden (1971) using the TVSS, to be better than a full-field scan mode. Loomis's theory predicts that the sequential mode would be superior to other modes because "one would expect letter recognition to be limited more by localization acuity than by spatial resolution.…”

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confidence: 97%

Tactile letter recognition: Pattern duration and modes of pattern generation

Craig

1981

Perception & Psychophysics

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Measurements were made of the ability of subjects to identify vibrotactile patterns presented to their fingertips. The patterns were letters of the alphabet generated on the tactile display of the Optacon. Five different modes of pattern generation were examined. Two of the modes, static and scan, involved full-field presentations of the letters. In the remaining three modes, patterns were generated by presenting parts of the letters sequentially. In one mode, the letters were exposed by a slit passing across them. In the other two modes, the patterns were generated as though the letter were being drawn on the skin. Performance in all five modes was examined as a function of pattern duration, with durations ranging from 4 to 1,000 msec. Increasing duration, up to 400 msec, resulted in generally improved performance, although the functions relating performance and duration differed according to the mode of presentation. Contrary to previous results, the static mode produced the best overall performance level. Some possible reasons for the disagreement between the present results and previous results and some models of cutaneous pattern recognition are discussed.

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“…Beauchamp, Matheson, and Scadden (1971) found that drawing simple patterns out with a single point of light yielded better recognition performance than panning the same patterns with the camera. ApkarianStielau and Loomis (1975) and Loomis (1974) demonstrated that letters scanned horizontally by a moving vertical slit were more easily recognized than letters simply flashed on the tactile display.…”

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confidence: 99%

Interaction of display mode and character size in vibrotactile letter recognition

Loomis

1980

Bull. Psychon. Soc.

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Research with the Tactile Vision Substitution System, a device that converts optical patterns into vibrotactile patterns for display against the back, has shown that a simple pattern, such as a letter, is more easily recognized when presented sequentially than when presented in entirety all at once. In recent work with the Optacon, another such device using the surface of the finger for display, Craig (Note 2) has found quite the opposite result over an extensive range of pattern durations. The present study shows that the superiority of sequential presentation can be obtained with the Optacon if letters considerably smaller than usual are displayed. Sequential presentation is advantageous when the pattern information essential for recognition exceeds the spatial bandwidth of the sensory surface, whether it be the finger, back, or other skin surface_ In the normal usage of the Optacon, however, it appears that the spatial bandwidth of the finger suffices for the recognition of large roman letters.Research with the Tactile Vision Substitution System (TVSS), an electronic device that converts high-contrast optical patterns (e.g., letters) into vibrotactile patterns for display against the back, has shown that a simple pattern is more easily recognized when presented sequentially than when presented in entirety all at once. Beauchamp, Matheson, and Scadden (1971) found that drawing simple patterns out with a single point of light yielded better recognition performance than panning the same patterns with the camera. ApkarianStielau and Loomis (1975) and Loomis (1974) demonstrated that letters scanned horizontally by a moving vertical slit were more easily recognized than letters simply flashed on the tactile display. More recently, Saida, Shimizu, and Wake (Note 1) have shown a very sizable superiority of sequential presentation over static presentation, using a tactile display against the belly. Loomis (1974) interpreted the superiority of sequential presentation as a consequence of the limited spatial resolution of the cutaneous sense, reasoning that stimuli that fail to be resolved spatially when presented simultaneously often can be accurately perceived when presented sequentially. Extending his argument to include the fmger, Loomis argued that contrary results obtained with the Optacon, a device like the TVSS used for reading by the blind, were understandable for reasons relating to the very rapid rates at which the letters were sequentially presented.In a recent study with the Optacon, Craig (Note 2) has shown that slit-scan and other modes of sequential presentation lead not to better, but to poorer recognition performance over an extensive range of pattern durations. This result suggests that the limited-resolution hypothesis does not apply to the recognition of letters presented to the fmger with the Optacon, at least not in its normal usage. However, one would still expect that if letters are reduced to a size such that spatial resolution does limit their recognition, the earlier result of superior perfor...

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Effect of Stimulus-Change Method on Tactile-Image Recognition

Cited by 16 publications

References 3 publications

Tactile letter recognition under different modes of stimulus presentation

Tactile letter recognition under different modes of stimulus presentation

Tactile letter recognition: Pattern duration and modes of pattern generation

Interaction of display mode and character size in vibrotactile letter recognition

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