Number of co-authors:26
Number of publications with 3 favourite co-authors:Ryan P. Blood:2Charlotte Lewis:2Jennifer L. Bruno Garza:1
Peter W. Johnson's 3 most productive colleagues in number of publications:Michael C. Bartha:6Jack T. Dennerlein:4Traci L. Galinsky:4
Civilization advances by extending the number of important operations which we can perform without thinking of them.
-- Alfred North Whitehead
Read the fascinating history of Wearable Computing, told by its father, Steve Mann
Read Steve's chapter !
Peter W. Johnson
Publications by Peter W. Johnson (bibliography)
Kim, Jeong Ho, Aulck, Lovenoor, Bartha, Michael C., Harper, Christy A. and Johnson, Peter W. (2012): Are there Differences in Force Exposures and Typing Productivity between Touchscreen and Conventional Keyboard?. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1104-1108.
As the use of tablets is becoming increasingly prevalent, it is important to understand how using a touchscreen (virtual) keyboard affects typing forces, productivity and comfort. Thus, the objective of this study was to investigate whether there were differences in typing forces, typing productivity and users' discomfort between virtual and conventional keyboards. A total of 19 subjects (10 males and 9 females) typed for 10 minutes on a virtual keyboard and two conventional keyboards. The results showed that virtual keyboard use resulted in lower typing forces (p < 0.0001), lower typing performance (p < 0.0001), and higher subjective discomfort at the hand/wrist and the neck/shoulder (p < 0.0001). The results indicate that using a virtual keyboard may not cause any detrimental effect on physical exposures, but may increase musculoskeletal discomfort on the upper extremities and neck/shoulder regions; therefore, appropriate interventions should be considered for the prolonged use of a virtual keyboard.
© All rights reserved Kim et al. and/or Human Factors and Ergonomics Society
Garza, Jennifer L. Bruno, Eijckelhof, Belinda H. W., Huysmans, Maaike A., Johnson, Peter W., Dieen, Jaap H. van, Beek, Allard J. van der and Dennerlein, Jack T. (2012): The effects of psychosocial factors on trapezius muscle activity levels during computer use. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1123-1127.
The goal of the present study, a part of the PROOF (Predicting Occupational biomechanics among OFfice workers) study, was to determine if there was a relationship between psychosocial stress, measured by reward and over-commitment, and trapezius muscle activity while workers performed their own computer work in the field. We observed that workers reporting higher levels of over-commitment and lower reward also experienced approximately 40% higher median trapeizus muscle activity levels than workers reporting lower levels of over-commitment and lower reward (change from 3.5% MVC to 6% MVC), with no difference in muscle activity for workers reporting high reward and either low or high over-commitment. Workers reporting higher levels of over-commitment experienced more variability in trapezius muscle activity. The results of this study may be used to inform interventions targeting reduction of musculoskeletal disorders among office workers.
© All rights reserved Garza et al. and/or Human Factors and Ergonomics Society
Thamsuwan, Ornwipa, Blood, Ryan P., Lewis, Charlotte, Rynell, Patrik W. and Johnson, Peter W. (2012): Whole Body Vibration Exposure and Seat Effective Amplitude Transmissibility of Air Suspension Seat in Different Bus Designs. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1218-1222.
A number of studies have shown that whole body vibration (WBV) exposures contribute to low back pain in vehicle operators. Bus design may be an important factor in determining the WBV exposures that a driver receives. The purpose of this study was to determine whether differences exist in WBV exposures among three buses commonly used in long urban commuter routes: a high-floor coach bus, a low-floor coach bus, and a low-floor articulating bus. Each bus had the same new air-suspension installed and was driven over a standardized test route which included four road types: a smooth freeway, a rough freeway, a city street segment, and a road segment containing several speed humps. WBV exposures were evaluated per ISO 2631-1 action limits for acceptable WBV exposure levels. In this study, there were statistically significant differences among buses in WBV exposures. The high-floor coach bus had the highest fore-aft (x-axis) exposures, the low-floor articulating bus had the highest lateral (y-axis) exposures and the low-floor coach bus had the highest vertical (z-axis) exposures. With respect to ISO action limits, the z-axis WBV exposures did not exceed the 8-hour action limit (0.5 m/s2). The study also found that the air suspension seat did not perform well in the coach buses. The air suspension seat transmitted 92% of the floor measured vibration to the seat of the operator on the high-floor coach bus, 88% on the low-floor bus, and 76% on the low-floor articulating bus. Due to the low vibration attenuation performance of the air suspension seat, an evaluation of the different types of seats and seat suspensions may be merited in future research.
© All rights reserved Thamsuwan et al. and/or Human Factors and Ergonomics Society
Hughes, Margaret, Aulck, Lavi and Johnson, Peter W. (2011): Are there Differences in Typing Performance and Typing Forces between Short and Long travel Keyboards?. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 954-957.
With keyboards gravitating towards thinner designs (shorter key travel distances) it is important to understand how these short travel keyboards may affect typing performance, typing forces and operator comfort. Using 15 subjects (7 males, 8 females), we wanted to determine whether there were differences in typing performance when computer operators typed on three keyboards with the same activation force (0.6 N) but with different key travel distances (2.0mm, 2.5mm and 4.0mm). During a 15 minute typing session on each keyboard, typing performance (speed and accuracy), typing forces and perceived fatigue ratings were measured. There were no differences in typing speed (p = 0.39), typing accuracy (p = 0.33) or keystroke durations (p = 0.15) across the three keyboards. However, typing force differences were measured (p < 0.003) with the longest travel keyboard (4.0mm) having higher mean and peak forces compared to the shorter travel keyboards (2.0 and 2.5 mm). These findings indicate that there is no apparent detriment in physical exposure or typing performance when using shorter travel keyboards.
© All rights reserved Hughes et al. and/or HFES
Hughes, Erin and Johnson, Peter W. (2011): Child Computer Use and Anthropometry. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1716-1719.
Despite all of the literature that exists on ergonomic considerations for adult computer use, there is a deficit of established objective data on how computer input device designs may affect children. By applying the relevant anthropometric data from children to the design of computer input devices, we have developed recommendations which may lead to new standards for child- and gender-specific computer input device designs, specifically, regarding mouse size (length, width, height, switch location), and mouse-button activation forces. Trends yielded four major size delineations based on age and gender, which happen to correspond well with the conventional grouping of grades in school in the United States. The data support that children and adult females may benefit from stature proportionate mice based on anthropometry.
© All rights reserved Hughes and Johnson and/or HFES
Blood, Ryan P., Dennerlein, Jack, Lewis, Charlotte, Rynell, Patrik and Johnson, Peter W. (2011): Evaluating whole-body vibration reduction by comparison of active and passive suspension seats in semi-trucks. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1750-1754.
Truck drivers have one of the highest injury rates in the US workforce with the majority of injuries occurring in the low-back. Exposure to Whole Body Vibration (WBV) is thought to be a significant factor. This study compared difference in WBV exposures in sixteen drivers who drove a semi-truck over a standardized test route with a passive (air suspension) and electromagnetic vibration cancelling (active suspension) seat. Tri-axial WBV measurements of average weighted vibration (Aw), Vibration Dose Value (VDV), and Static Compressive Dose (Sed) were collected and compared between the two seats. Vehicle speed and location was collected with GPS loggers. The results show when compared to the passive suspension seat, the active suspension seat reduced Aw (p<0.001) and VDV (p<0.001) vibrations exposures by roughly
© All rights reserved Blood et al. and/or HFES
Hwang, Sean and Johnson, Peter W. (2010): Computer Input Devices Race and Gender: Is there a mismatch between anthropometry and input device design. In: Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting 2010. pp. 1130-1133.
Studies have shown an association between intensive computer use and the onset and development of upper extremity musculoskeletal disorders. However, the evidence for possible health effects related to computer input device design and operator anthropometry is limited. The aim of this study was to systematically examine relationships between the current sizing of computer input devices and key anthropometric differences, based on gender and race, in adult computer users. Computer input devices appear to be designed based on anthropometric clearance issues to accommodate the largest users (95th percentile Western males). Based on this current design, less than 6.1% of the worldwide population would "fit" the current pointing device and keyboard design standards. Finger mass is a critical component for determining device activation forces When comparing male and female hand anthropometry, finger mass accounted for the largest anthropometric difference with the 50th percentile females' hand only 73% the mass of the 50th percentile males'. With respect to similarities, in virtually every aspect of seated workstation anthropometry (i.e. furniture requirements), the 50th percentile Western female very closely approximated the 50th percentile Asian male. The findings of this study indicate that gender and race base differences in workstation design are small relative to the differences in input device activation forces based on hand anthropometry. It appears that the current "one size fits all" paradigm used to design computer input devices may not be optimal. Smaller devices with lower activation forces could benefit a large percentage of the world population.
© All rights reserved Hwang and Johnson and/or HFES
Johnson, Peter W. and Cui, Ling (2010): Postural benefits for children and adults when using the mouse next to a small keyboard. In: Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting 2010. pp. 1794-1796.
Studies have shown that there are adverse performance and postural impacts when children use standard, adult-sized computer mice; however, the impact of children using adult-sized keyboards has been less rigorously evaluated. The aim of this study was to investigate whether there were any postural and performance differences when children and adults used the mouse next to a standard 104 key keyboard with a numeric keypad compared to a small, more compact keyboard without a numeric keypad. A total of 42 subjects, including 28 adults and 14 children between the ages 6-8 participated in the study. Subjects were asked to perform a series of standardized point-and-click tasks using a standard-sized mouse with both the standard and small keyboard. During mouse operation arm abduction and forearm rotation were measured using overhead photographs, and mouse performance was characterized by measuring movement times and the time it took to press-and-release (click) the left mouse button. Compared to the standard keyboard, both children and adults had less arm abduction (p < 0.10) and external rotation of the forearm (p < 0.05) when using the mouse next to the small keyboard. When comparing children to adults, children worked with significantly more arm abduction with both keyboards; however there were no significant differences between children and adults in internal and external rotation of the forearm. When comparing performance, children took almost twice as long to move the mouse between targets (p < 0.05) and were slightly faster when operating the mouse next to the small keyboard. In addition, compared to adults, it took children twice as long to press and release the mouse button. The study findings indicate that children would benefit from a postural standpoint if computer manufacturers sold, and schools and parents purchased, computers with smaller keyboards. The two-fold difference between children and adults in the time it took actuate the mouse button indicate that mouse button activation forces may need to be lower for children.
© All rights reserved Johnson and Cui and/or HFES
Morelli, Donald L., Johnson, Peter W., Reddell, Cheryl R. and Lau, Patricia (1995): User Preferences between Keyboards While Performing "Real" Work: A Comparison of. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 361-365.
The proliferation of varying computer keyboard designs may pose problems to those who specify, purchase and ultimately use such devices. Are any of them "best" for my work? Will actual users derive any benefit from them? To assist in addressing such issues, we explored an approach to determining if any of three "alternative" keyboards provided a benefit to employees by increasing user comfort. A total of 34 employees participated in this study, each using an "alternative" keyboard for one week at a time while performing their actual work. After using each keyboard, including their standard "101" keyboard, subjects completed a questionnaire of seven psychophysical measures relating to the comfort and use of the keyboard. Questionnaire responses were tabulated and a Repeated Measures Analysis of Variance conducted. Statistically significant differences were found among and between the four keyboards on four of the seven psychophysical measures. Overall results showed little differences in user assessments between three of the keyboards, with the fourth keyboard assessed less favorably when significant differences were found. The results suggest that user assessments can produce significant results between keyboards, and that no one "best" keyboard exists for any given set of tasks and group of users.
© All rights reserved Morelli et al. and/or Human Factors Society
Grant, Katharyn A., Galinsky, Traci L. and Johnson, Peter W. (1993): Use of the Actigraph for Objective Quantification of Hand/Wrist Activity in Repetitive Work. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 720-724.
Valid and reliable measures of hand/wrist activity are needed to address the relationship between work tasks and the development of upper extremity musculoskeletal disorders. The utility of the actigraph for measuring wrist activity in manual work was examined in this study. Ten grocery cashiers and four non-cashier retail workers wore actigraph monitors on both wrists and the left ankle during their normal work activities. Work activities were periodically observed and recorded on videotape. Data recorded by the actigraphs were matched against observational data. The results indicated that actigraphy was effective in detecting significant work-related variations in physical activity in the three limbs studied. Compared to traditional observational procedures, actigraphy represents a cost-effective approach for obtaining objective and quantitative information about the intensity and duration of work over long time periods. Traditional observational procedures, however, are necessary to provide additional information needed for a complete job analysis (e.g., postural data). Continuous activity recordings can be used in conjunction with sampling protocols to examine the relationship between work-related physical activities and musculoskeletal trauma.
© All rights reserved Grant et al. and/or Human Factors Society
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