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Subjective Perception of Load Heaviness

Lee T. H.

International Journal of Occupational Safety and Ergonomics

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2014

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Vol. 20, No. 3

421--427

EN

This study examined human subjective perception of load heaviness. Forty-two (3 boxes × 14 weights) and 27 (3 boxes × 9 weights) experimental conditions were randomly presented to male and female participants, respectively. The results showed that the participants were not able to discriminate the effect of the box on perceived weight. The participants underestimated the weight for low weights and overestimated it for high weights. The females perceived a greater increase in weight than the males for the same increase in weight. The participants’ linguistic term for perceived weight was positively correlated to the magnitude of weight. Approximately 50% of the males perceived a weight of 20 kg or over as risky, while ~60% of the females perceived a weight of 14 kg or over as risky. This study supposes that the gender difference in muscular capability is responsible for the effect of gender on the risk perception of weight.

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Effect of Background Music on Maximum Acceptable Weight of Manual Lifting Tasks

Yu R.

International Journal of Occupational Safety and Ergonomics

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2014

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Vol. 20, No. 3

437--445

EN

This study used the psychophysical approach to investigate the impact of tempo and volume of background music on the maximum acceptable weight of lift (MAWL), heart rate (HR) and rating of perceived exertion (RPE) of participants engaged in lifting. Ten male college students participated in this study. They lifted a box from the floor, walked 1–2 steps as required, placed the box on a table and walked back twice per minute. The results showed that the tempo of music had a significant effect on both MAWL and HR. Fast tempo background music resulted in higher MAWL and HR values than those resulting from slow tempo music. The effects of both the tempo and volume on the RPE were insignificant. The results of this study suggest fast tempo background music may be used in manual materials handling tasks to increase performance without increasing perceived exertion because of its ergogenic effect on human psychology and physiology.

3

Evaluation of Different Scales for Measurement of Perceived Physical Strain During Performance of Manual Tasks

Hernandez L., Alhemood A., Genaidy A. M., Karwowski W.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

413--432

EN

The main objective of this study was to evaluate different scales of perceived strain during the performance of various physical tasks. A total of 52 male and female participants took part in 4 experiments to achieve the study objective. The results suggest that a bipolar comfort-discomfort scale is a more appropriate instrument than a discomfort scale for assessing cumulative physical stresses at work, especially at the beginning of the shift. For assessing discomfort at the end of the work shift, a unipolar scale may also be used. On the basis of the obtained results, red, green, and yellow zones are suggested to establish priorities for work redesign efforts in ergonomic control programs.

4

Combining Psychophysical Measures of Discomfort and Electromyography for the Evaluation of a New Automotive Seating Concept

Kolich M., Taboun S. M.

International Journal of Occupational Safety and Ergonomics

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2002

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Vol. 8, No. 4

483--496

EN

The purpose of this study was to determine if the advantages and disadvantages of a new automotive seating concept, known as the micro-adjuster control system, could be reliably evaluated using both a physiological assessment technique (i.e., electromyography [EMG]) and a subjective questionnaire. The results indicate that psychophysical measures of discomfort and the root mean squared (RMS) activity of the EMG are statistically related, r (8) = –.788, p=.020. More specifically, subjective perceptions of comfort were found to improve with decreasing levels of muscle activity. This implies that seat comfort can be evaluated on the basis of physiological as well as subjective responses to prolonged driving. This finding should drastically improve automobile seat design efforts.