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Differential discrimination of frequency of cutaneous mechanical vibration
ttLI},IAN RESPONSE TO VIBRATION
787
E. J. Lovesey 1971 Royal Aircraft Establishment, Technical Report 71213 (EP 588). An investigation into the effects of dual axis vibration, restraining harness, visual feedback and control force on a manual positioning task. (44 pages, 10 figures, 22 tables, 5 references)
Author's Summary. A basic experiment was designed to investigate the influence of dual axis vibrations, restraining harness, visual feedback and control force, upon manual positioning, and the interactions between these various parameters. Three seated male subjects were exposed for about 40 seconds to distorted sinusoidal vibrations at frequencies of 2 and 2.7 Hz, with amplitudes in heave of +0-25 g and in sway of • g. Heave and sway vibrations were applied singly and in combination, while the subject performed a simple two-dimensional positional control task. All vibrations were found to affect adversely control accuracy when positioning a target spot at the centre of a head-up display using a ramshorn type aircraft control column. Generally, heave vibrations degraded positional control the least, while sway produced a moderate decrement. Dual axis heave and sway vibration reduced control accuracy by an amount greater than the sum of the amounts produced by each component alone. The addition of a bias in the position of the controls and corresponding increase in required control force appreciably increased errors. The use of a restraining harness slightly increased positional errors over the unrestrained case. The absence of visual feedback increased gross.movements of the controls but decreased the incidence of the subject induced smaller perturbations. In general, the greatest control errors were produced by dual axis vibrations coupled with the addition of control force. The influences of harness and visual feedback had a lesser effect upon positional control. Topics: Performance (Psychomotor); Non-vertical Vibration (Lateral).
G. D. Goff 1967 Journal of ExperimentalPsychology 74, 294--299. Differential discrimination of frequency of cutaneous mechanical vibration. (6 pages, 5 figures, 19 references)
Author's Abstract. Measurements of differential threshold (deltaf ) of a cutaneous mechanical vibratory stimulus are accurate only if concomitant changes in subjective intensity of the stimulus are eliminated. In this study, curves of equal subjective intensity were first obtained from four subjects at two intensity levels, 20 and 35 dB above the absolute threshold of the I00 Hz standard. Deltafwas then measured at 25, 50, 100, 150, and 200 Hz, all amplitudes being within the equal intensity curve of the particular subject. With intensity cues thus eliminated, deltafis small below I00 Hz but then increases markedly. It is lower at the higher intensity level. Topics: Vibration Sense (Thresholds). B. Hellstrom and K. Myhre 1971 British Journal of hl&tstrial Medicine 28, 272-279. A Comparison of some methods of diagnosing Raynauds phenomena of occupational origin. (8 pages, 5 figures, 7 tables, 33 references)
Author's Abstract. The aim of the present study was to compare some field methods of diagnosing traumatic vasospastic disease (TVD). Eleven forest workers with TVD (Raynauds phenomena of occupational origin) from the use of chain saws and seven controls underwent
787
E. J. Lovesey 1971 Royal Aircraft Establishment, Technical Report 71213 (EP 588). An investigation into the effects of dual axis vibration, restraining harness, visual feedback and control force on a manual positioning task. (44 pages, 10 figures, 22 tables, 5 references)
Author's Summary. A basic experiment was designed to investigate the influence of dual axis vibrations, restraining harness, visual feedback and control force, upon manual positioning, and the interactions between these various parameters. Three seated male subjects were exposed for about 40 seconds to distorted sinusoidal vibrations at frequencies of 2 and 2.7 Hz, with amplitudes in heave of +0-25 g and in sway of • g. Heave and sway vibrations were applied singly and in combination, while the subject performed a simple two-dimensional positional control task. All vibrations were found to affect adversely control accuracy when positioning a target spot at the centre of a head-up display using a ramshorn type aircraft control column. Generally, heave vibrations degraded positional control the least, while sway produced a moderate decrement. Dual axis heave and sway vibration reduced control accuracy by an amount greater than the sum of the amounts produced by each component alone. The addition of a bias in the position of the controls and corresponding increase in required control force appreciably increased errors. The use of a restraining harness slightly increased positional errors over the unrestrained case. The absence of visual feedback increased gross.movements of the controls but decreased the incidence of the subject induced smaller perturbations. In general, the greatest control errors were produced by dual axis vibrations coupled with the addition of control force. The influences of harness and visual feedback had a lesser effect upon positional control. Topics: Performance (Psychomotor); Non-vertical Vibration (Lateral).
G. D. Goff 1967 Journal of ExperimentalPsychology 74, 294--299. Differential discrimination of frequency of cutaneous mechanical vibration. (6 pages, 5 figures, 19 references)
Author's Abstract. Measurements of differential threshold (deltaf ) of a cutaneous mechanical vibratory stimulus are accurate only if concomitant changes in subjective intensity of the stimulus are eliminated. In this study, curves of equal subjective intensity were first obtained from four subjects at two intensity levels, 20 and 35 dB above the absolute threshold of the I00 Hz standard. Deltafwas then measured at 25, 50, 100, 150, and 200 Hz, all amplitudes being within the equal intensity curve of the particular subject. With intensity cues thus eliminated, deltafis small below I00 Hz but then increases markedly. It is lower at the higher intensity level. Topics: Vibration Sense (Thresholds). B. Hellstrom and K. Myhre 1971 British Journal of hl&tstrial Medicine 28, 272-279. A Comparison of some methods of diagnosing Raynauds phenomena of occupational origin. (8 pages, 5 figures, 7 tables, 33 references)
Author's Abstract. The aim of the present study was to compare some field methods of diagnosing traumatic vasospastic disease (TVD). Eleven forest workers with TVD (Raynauds phenomena of occupational origin) from the use of chain saws and seven controls underwent