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Man-Machine Systems, IEEE Transactions on

Issue 1 • Date March 1970

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Displaying Results 1 - 25 of 28
  • [Table of contents]

    Page(s): c1
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    Freely Available from IEEE
  • IEEE Man-Machine Systems Group

    Page(s): c2
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  • Editorial: Dynamic Tactile Displays in Man-Machine Systems

    Page(s): 1
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  • The Afferent Discharge Elicited by Vibrotactile Stimulation

    Page(s): 2 - 5
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    When skin is mechanically stimulated, differentreceptor systems will be activated depending upon the type of skin stimulated and stimulus characteristics such as rate and amplitude of displacement and repetition frequency. The general properties of the primary mechano-receptive units are (for the rapidly adapting intracutaneous receptors) low thresholds, restricted receptive field, relatively good rate sensitivity (in terms of repetitive impulse discharge), and poor capacity of tracking on high-frequency repetitive stimulation; (for the Pacinian corpuscles) high critical slope, very low displacement threshold, diffuse receptive field, poor rate sensitivity, and good frequency-following capacity; (for the tactile spots in hairy skin) low displacement threshold, small receptive field, good rate sensitivity, and good frequency-following capacity. When tactile displays are designed, the stimulus parameters will have to be chosen according to the psychophysical functions as well as to the receptor properties, in order to obtain a device that is optimal from a discriminatory point of view. View full abstract»

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  • Choice of Stimulator Frequency for Tactile Arrays

    Page(s): 5 - 11
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    An experiment is described that tested subjects' ability to recognize letters presented tactually by an array of airjets in a manner simulating a moving belt. Recognition accuracy was measured as a function of reading rate and stimulator frequency. For constant stimulus pulsewidth, performance increased significantly as stimulator-repetition rate was increased from 20 to 160 pps. A second experiment is discussed that is designed to measure the spatial resolution of two hypothetical neural systems, which are the basis for tactile sensations. The data presented indicate that sensitivity to differences in amplitudes of two stimulators is comparable for spacings of 6-10mm on the fingertip. At spacings of 2 mm there is a significant difference between the two systems with the superior resolution obtained at the high frequencies. View full abstract»

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  • The Measurement of Fluctuation in Perceptual and Learning Tasks

    Page(s): 11 - 19
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    In psychophysical experiments subjects always produce responses that are not nearly as constant as the stimuli presented in laboratory conditions. In this study the fluctuation of responses is described as originating in the nervous system. This description requires a definition of three quantities: a measure for the total neural activity elicited by the stimulus, the fluctuation of this activity about the mean, and the criterion value set by the subject. The method is used in the case of electrical and tactile pulses applied to the skin. This experiment is extended to the case where the test pulse is masked by another simultaneous pulse at an adjacent location. Also, in many learning experiments the response does not improve from trial to trial but it is the mean of fluctuating responses, which shows a learning phenomenon. Here again a theoretical description requires the definition of three quantities: a measure for the state of the nervous system telling its aptitude to show the required response, the fluctuation of this aptitude about the mean, and the criterion value set by the experimental environment. These theoretical considerations are applied to the learning of a compensatory tracking task with two different displays: a visual display and a tactile display. View full abstract»

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  • Subjective Magnitude Functions for Vibrotaction

    Page(s): 19 - 24
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    An investigation of the subjective magnitude of vibrotaction was undertaken in order to 1) determine the growth of sensation as a function of intensity at a number of different frequencies; 2) establish contours of equal subjective intensity for vibrotaction; and 3) compare the psychophysical methods of direct scaling and intensity matching for a wide range of intensity and frequency. The results show that the growth of sensation is a power function having a slope of about 0.89 for frequencies up to 350 Hz. Near the threshold of detectability the subjective magnitude is proportional to the physical intensity. Contours of equal subjective magnitude were established at eleven levels of intensity and across ten frequencies. It is clearly shown that data obtained by direct scaling and by interfrequency-intensity matching are comparable. View full abstract»

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  • Temporal Ordering of Events in Haptic Space

    Page(s): 25 - 28
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    The most rapid acquisition of skill in the use of complex vibrotactile displays will occur when the capabilities of the organism are most efficiently exploited by the display code. When spatiotemporal patterns are chosen as the coding scheme, the problem of perception of temporal order is of great importance. The present paper describes the effects on the limen for order of two events, of the quality of the stimuli, their spacing on the body, and their intensive relations. The results suggest the presence of limiting conditions for the spatial and, by analogy, the temporal density of vibrotactile patterns. Comparisons are made with results reported previously, and a hypothesis is developed concerning the onset and timing of stimuli in relation to the capacity of the nervous system to augment the clarity of sensory events and to transfer the argumentation to successive locations on the sensory surface. View full abstract»

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  • Some Comparisons between Touch and Hearing

    Page(s): 28 - 35
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    The skin can be used for sound localization with accuracy nearly as good as that for hearing. However, auditory sound localization is based on the utilization of both intensive-difference and temporal-difference cues while cutaneous sound localization is based almost entirely on the utilization of only intensive-difference cues. Furthermore, the time interval necessary for resolving two temporally separated pulses was found to be 2.0 ms for binaural and monaural stimulation and, at best, 10 ms for stimulation of the skin. The superior temporal acuity of the ears over the skin was again demonstrated by the finding that pairs of auditory pulses separated by less than 30 ms were perceived as more separated in time than pairs of cutaneous stimuli separated by the same time interval. A series of experiments was conducted to measure inhibitory interaction between touch and hearing. When absolute thresholds were measured by a tracking method in which the subject was free to vary his judgment criterion, auditory stimulation by a click was found to increase tactile thresholds for mechanical pulses by as much as 5.0 dB. Intense tactile pulses slightly increased the auditory click threshold. Subsequent experiments using signal-detection methodology revealed that auditory-tactile masking is caused by a slight reduction in stimulus detectability accompanied by a corresponding increase in the subject's criterion. View full abstract»

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  • Stimulus Feature Detection by Neurons in Somatosensory Areas I and II of Primates

    Page(s): 36 - 38
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    The responses of individual neurons in the cerebral cortex of unanesthetized macaques to moving cutaneous stimuli are described. In somatic sensory area I, 70 percent of the neurons studied exhibit a directional polarization to stimuli moving in opposite direction. In somatic sensory area II, the magnitude of responses is determined by more complex concatenations of stimulus properties, as regards direction of stimulus motion and site of stimulus application on the body. View full abstract»

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  • Sensory Role of Impulses Traveling in the Dorsal Columns

    Page(s): 39 - 44
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    In the classical theory of cutaneous sensation, detailed discrimination depends on impulses conducted to cortex over the newly evolved dorsal columns. This idea is no longer tenable because, when this system is destroyed, animals can still discriminate weight, texture, vibration, two points, and position. If all parallel ascending systems are destroyed except for the dorsal columns, the dorsal colunms alone are unable to initiate any behavior. Positive results of dorsal column section are all related to movement: failure of orientation; failure to handle objects in extrapersonal space; and the presence of immobility, especially in the absence of vision. In an attempt to explain these results, it is proposed that dorsal column impulses do not lead to sensation, but act to initiate and control an internal search of messages arriving over other pathways. When this search fails to provide adequate information for identification of the stimulus, an external search or exploration begins, and it is proposed that dorsal columns are necessary for this search too. In these proposals, the new system sets the program on which the older systems operate so that the new system is only essential for sensation when program change and manipulation is essential in the older pathways. View full abstract»

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  • Visual Word Reading

    Page(s): 44 - 53
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    In an attempt to gain more knowledge about the human reading process, some experiments were performed using a computer-controlled array of 144 neon lights to simulate a "moving belt" of English text. Subjects were asked to read aloud as the width of the display and horizontal resolution over the display were varied. For the variable-width high-resolution conditions, excellent comprehension was obtained if each point of the moving patterns was visible for at least 150 ms while traveling across the aperture of the display. This 150-ms display-time requirement means that, for a high level of comprehension, reading rate is proportional to the width of the display aperture until the maximum reading speed of the subject is reached. If the subjects are reading over 50 words per minute, the variable resolution results indicate that greater reading speed can be obtained by distributing the same number of neon lights over a wider field of view. Reading with analogous tactile arrays by blind subjects was compared with these visual results and showed good agreement. A simple model of the human reading process consistent with these results is presented and discussed. These results have direct bearing on the design of displays with optimum information-transfer capabilities. View full abstract»

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  • Perceptual Findings with the Vision-Substitution System

    Page(s): 54 - 58
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    The initial evaluation of a system for converting an optical image into a tactile display is reported. A 400-tactor array has proved capable of providing blind and sighted subjects with useful information about the disposition of objects in three dimensions. External localization of percepts was greatly facilitated by giving observers control of the sensing and imaging device, a television camera. There has been a surprising similarity between the blind and sighted observers in their manner and speed of gaining facility with the system. The system's limitations thus far appear to be due more to the low resolution of the display than to the skin's shortcomings as a receptor surface. View full abstract»

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  • Optical-to-Tactile Image Conversion for the Blind

    Page(s): 58 - 65
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    This paper describes two optical-to-tactile imageconversion systems being developed for the blind. The first is a reading aid in which an area on the printed page about the size of a letterspace is translated into a corresponding vibratory tactile image. The tactile image is produced by a 24-by-6 array of pins driven by piezoelectric bimorphs. The array of 144 pins fits on the distal and a portion of the middle phalanges of one finger. The piezoelectric bimorphs cause the pins to impact the skin in a nonlinear manner. Precise measurements on this bimorph-finger system are given. These measurements also show that shades of "grey" can be displayed by sequentially varying the threshold level. Three experiments conducted with the reading aid involved measurement of legibility, reading rate, and the effect of field of view. Legibility in the 92-98 percent range was obtained at the design magnification. A reading rate of 50 words per minute was achieved with one subject after roughly 160 hours of practice. Three other subjects achieved reading rates of over 10 words per minute after about 40 hours of practice. Reading rate increased markedly as the number of columns in the array was varied from one to six. The second optical-to-tactile image-conversion system is merely an extension of the first to permit information to be acquired from the environment. In fact, ultimately only one system with two sets of optics, one appropriate for the printed page and one appropriate for environment sensing, would be used. View full abstract»

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  • Tactile Television - Mechanical and Electrical Image Projection

    Page(s): 65 - 71
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    The feasibility of communicating pictorial information through the skin has been demonstrated. A tactile television system has permitted blind subjects to determine the position, size, shape, and orientation of visible objects and to track moving targets. The system comprises 1) a vidicon camera utilizing a zoom lens, 2) a digital switching matrix to sequentially connect each element of the photocathode surface through a single video amplifier and signal conditioner to each of the 3) 400 tactile stimulators in a 20 × 20 matrix in contact with a 10-inch square of skin. This image-projector matrix impresses on the skin a two-dimensional vibrating facsimile of either the silhouette or the outline of a visible object. The single-channel swept system exhibits inherent economies when a great number of picture elements is to be processed. Since the fovea of the human eye subserving the central two degrees of detailed vision is comprised of cone cells in a matrix about 200 receptors across, the present 20-line system permits picture transmission with a linear resolution about one-tenth that of the fovea, and has proved adequate for the recognition of human faces. Calculations indicate that the input capacity of the skin of the trunk should compare favorably with that of the fovea. We have determined the electrical-stimulus parameters for painless stimulation of the sensation of mechanical vibration with small electrodes in a closely spaced matrix. View full abstract»

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  • An Electrotactile Display

    Page(s): 72 - 79
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    An explorable electrotactile display has been constructed and tested. A thus far neglected sensation was identified and has been shown to be more useful than the more common electrotactile sensations. Exploration of the surface of the electrotactile display elicits a sensation describable as texture. Experiments have indicated that the intensity of this texture sensation is due primarily to the peak applied voltage rather than to current density as is the case for the classical electrotactile sensation. For subjects employing the texture sensation, experimental results are given for approximate thresholds and for the effect of electrode area on these thresholds. A boundary-localization measurement is offered as a measure of the usefulness of the display for textured-area presentation, and form-separation measurements are given as a measure of usefulness for line-drawing presentations. A proposed model for the mechanism producing the texture sensation is offered as a guide for future experimentation and display-engineering development. View full abstract»

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  • A Survey of the Mechanical Characteristics of Skin and Tissue in Response to Vibratory Stimulation

    Page(s): 79 - 84
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    The possibility that the mechanical characteristics of skin and tissues may influence physiological and psychophysical measurements of tactile sensitivity is considered. A survey of selected literature indicating how certain mechanical characteristics of skin and tissue vary as a function of changes in variables known to influence physiological and psychophysical measurements of the tactile system is presented. Finally, certain physiological and psychophysical studies in which the physical properties of the area stimulated may have influenced the results are mentioned. View full abstract»

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  • Information Transmission by Phantom Sensations

    Page(s): 85 - 91
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    A sensory-aids display system that transmits information to its user through the location of a vibratory sensation on the skin has been developed. The sensation location is controlled by use of the phantom-sensation phenomenon. The development of the display included the determination of sensory and mechanical characteristics of the skin. The system was evaluated as a kinesthetic feedback display from the elbow prostheses for above-elbow amputees. View full abstract»

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  • A Describing Function Analysis of Tracking Performance Using Two Tactile Displays

    Page(s): 92 - 101
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    A display consisting of two vibrators attached to the body was tested using three different error signal-to-vibration amplitude transformations. In addition, a novel ripple display consisting of seven sequentially activated air-jet stimulators was tested on a compensatory tracking task. For both displays the range of gains and body locations were determined by both describing-function and error-power analyses. The results showed that the two-vibrator display was equally effective on all five body areas tested, but that the ripple display produced best tracking performance only when widely spaced or situated on an anatomical landmark. The best ripple display, however, was better than the best vibrator display and provided tracking performance nearly equivalent to visual displays. It was found that the ripple display was not enhanced by apparent motion but produced equivalent operator time delays shorter than those measured with visual displays. View full abstract»

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  • A Provisional Bibliography on Tactile Displays

    Page(s): 101 - 108
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    First Page of the Article
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  • Neurophysiological Basis of a Tactile Vision-Substitution System

    Page(s): 108 - 110
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    The instrumentation produced and the results obtained with the tactile vision-substitution system (TVSS) developed in our laboratories have been described by Collins [1] and White [2]. With the TVSS, the information from a TV camera is carried to the brain by means of the tactile receptors in the skin of the back and their neural pathways. Such information produces subjective impressions in blind subjects that are analogous to the subjective impressions produced by the visual input in normal sighted people. Some of the neural mechanisms underlying the systems design and the results obtained with the TVSS are noted. View full abstract»

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  • Kinesthetic Sensing for the EMG Controlled "Boston Arm"

    Page(s): 110 - 115
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    The contribution of a novel cutaneous display of elbow angle to an amputee's ability to position an EMG-controlled externally powered elbow prosthesis was objectively evaluated. Comparisons were made between the amputee's positional control of his conventional mechanical cable-operated elbow and the EMG "Boston Arm"l elbow, with and without angle feedback, in REACHING tasks with vision occluded in all cases and with and without auditory occlusion. MATCHING tasks compared his ability to position the EMG limb to conform with the flexion of his normal (contralateral) elbow. Computer reduction of almost 9000 individual trials and analysis of variance indicated that for the EMG limb the tactile feedback with sound occluded reduced errors by 50 percent. Terminal device load did not significantly affect positioningperformance due to the force proprioception built into the Boston Arm. In comparison with the standard mechanical prosthesis, the EMG limb with feedback achieves virtually identical kinesthetic performance. The display is completely compatible with the EMG control, causes no discomfort to the wearer, and is not significantly degraded by the environmental conditions of the limb socket. View full abstract»

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  • Neural Activity in the Somatic Primary Receiving Area of the Human Brain and Its Relation to Perceptual Estimates

    Page(s): 115 - 117
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    Experiments were performed to establish the relation between scales of perceived intensity and primary cortical potentials obtained under identical stimulation conditions. When the maximal positive-negative deflection of the primary component of the averaged evoked potential was plotted against stimulus displacement, all data were well represented by power functions with exponents of nearly the same size as those of the psychophysical functions. The results indicate also that spatial summation takes place when two neighboring locations are stimulated with an increase in apparent intensity of only about ¿2 of that corresponding to monodigital stimulation. View full abstract»

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  • Contributors

    Page(s): 120 - 122
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    Freely Available from IEEE