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Advances in industrial ergonomics and safety III
ABSTRACTS 23.5.14 (125634) Takala, E P and Viikari-Juntura, E 'Loading of shoulder muscles in a simulated work cycle: comparison between sedentary workers with and without neck-shoulder symptoms' Clin Biomech Vol 6, No 3 (1991) pp 145-152 (31 refs)
largest near the joints. Data collected in this study could be used to create a set of overlapping ellipsoids that would provide a more accurate representation of hand geometry, and this representation could be adapted to biomechanical models that use ellipsoids to define segment geometry.
Ten female bank cashiers with frequent neck-shoulder symptoms and ten non-symptomatic referents (matched by age, body size and work experience) doing similar work performed a work simulation demanding attention and static holding of the arm. Surface electromyography was recorded on the upper trapezius and rhomboideus/ erector spinae muscles. The static load moments of the working arm were calculated from still video pictures. No significant differences were found between the two groups in electromyographic activity on the working or on the opposite resting side, although the subjects with frequent symptoms showed greater variation in electromyographic activity. Changing the location of the task from the distance of the upper limb length and eye level to a location about 10 cm lower and 10 cm closer to the subject reduced the electromyographic activity of the trapezius muscles by 25-30%.
23.5.16 (125646) Brown, R T, Page, G B and McMahan, PB 'A biomechanical evaluation of railroad car hand brake operating methods' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety III Taylor & Francis, London (1991) pp 405-412 (6 refs) Current hand brake operating methods were evaluated to determine which methods allow workers to apply maximum force to the brake wheel while satisfying NIOSH criteria for back compression and strength capability. Three types of hand brake and two operating methods for each brake type were studied. Factors affecting the worker's operating posture were also considered in the analysis. Evaluation criteria were NIOSH Action Limits for back compression and strength capability. Maximum hand force for 64 different operating postures were determined using the University of Michigan 3D Static Strength Prediction ProgramTM. Preferred operating methods for each type of hand brake are presented, limitations of the methodology are identified, and plans for subsequent research are discussed.
23.5.15 (125642) Buchholz, B and Armstrong, T J 'An ellipsoidal representation of human hand anthropometry' Hum Factors Vol 33 No 4 (1991) pp 429-441 (6 refs) The goal of this study was to collect anthropometric data that describe the geometry of the surface of the hand and to model this anthropometry as a function of gross external hand measurements. The depth and breadth of each segment of the hand were measured at points that were spaced at approximately equal distances between the joints of the hand. Linear models using hand breadth as the independent variable explained from 12% to 47% of the variation in segment breadths and from 6% to 74% in segment depths. Ellipsoids are used in biomechanical models as an efficient mathematical description of the shape of kinematic segments for use in the determination of contact with other objects. Therefore the primary objectives of this study were to approximate the semi-axis dimension for these hand segment contact bodies using a linear model of the gross anthropometry and to evaluate the accuracy with which ellipsoids describe the geometry of the hand segments. Graphical components showed that differences between the ellipsoidai approximations and the breadth and depth measurements were
Vol 23 No 5 O c t o b e r 1992
23.5.17 (125653) Kumar, S, Phan, Q, Perry, P and Garand, D 'Push-pull strength at three heights' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety III Taylor & Francis, London (1991) pp 225-230 (12 refs) Ten young males and ten young females (mean age 21.1 years) were required to perform sagittally symmetrical maximal isometric and isokinetic push and pull exertion at 35 cm, 100 cm, and 150 cm height. Subjects performed these activities with their lower extremities (hip down) stabilized in a custom-designed device. The 12 experimental conditions were randomized. The strength was measured through a SM500 load cell in a specially designed strength tester. The collected data were fed on line to an IBM XT through a Metrabyte DAS 29 at a sampling rate of 50 Hz. The results revealed greatest strength in isometric pulling at 100 cm height. The isometric pushing strengths ranged between 41 and 68% and 27 to 44% for males and females respectively. The isokinetic
strengths were significantly lower than isometric strength (p < 0.Ol). The findings of the study suggest that jobsimulated appropriate gender-adjusted isokinetic strength should be used for job design. 23.5.18 (125681) Aykin, N M and Aykin, T 'Individual differences in humancomputer interaction' Comput Ind Eng Vol 20 No 3 (1991) pp 373-379 (50 refs) A comprehensive review of studies involving individual differences in human-computer interaction is presented. Past studies have revealed that certain user characteristics and user performance and preferences might be significantly related. In this review, user characteristics are classified into four groups: level of experience, personality traits, demographic characteristics and others. User characteristics that may affect user performance are discussed along with the advantages of incorporating them into human-computer interfaces. 23.5.19 (125685) Pocius, K E 'Personality factors in human-computer interaction: a review of the literature' Comput Human Behav Vol 7 No 3 (1991) pp 103-135 (76 refs) This is a review of studies investigating the relation between personality dimensions and human-computer interaction. The review is divided into three topic areas: programming aptitude and achievement, the programmer personality, and computer-assisted instruction (CAI). It is concluded as follows. (a) Introversion-extraversion and traits characterizing introversion-extraversion are related to many aspects of human-computer interaction. (b) There is little evidence to support a relation between the Jungian personality dimensions and programming aptitude and achievement. (c) Further, no correlations are reported between these dimensions and academic achievement in CAI-based courses; however, certain Jungian dimensions are related to attrition rate and speed of completion. (d) Although little relation between Jungian dimensions and programming aptitude and achievement is noted, certain personality types select careers that utilize computer programming. (e) Anxiety characterized by a threat to self-esteem facilitates or debilitates CAI performance contingent on specific aspects of the learning task. (f) Compulsive and stress-induced personality traits, internal-external locus of control, and achievement motivation are implicated in human-computer interaction performance.
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largest near the joints. Data collected in this study could be used to create a set of overlapping ellipsoids that would provide a more accurate representation of hand geometry, and this representation could be adapted to biomechanical models that use ellipsoids to define segment geometry.
Ten female bank cashiers with frequent neck-shoulder symptoms and ten non-symptomatic referents (matched by age, body size and work experience) doing similar work performed a work simulation demanding attention and static holding of the arm. Surface electromyography was recorded on the upper trapezius and rhomboideus/ erector spinae muscles. The static load moments of the working arm were calculated from still video pictures. No significant differences were found between the two groups in electromyographic activity on the working or on the opposite resting side, although the subjects with frequent symptoms showed greater variation in electromyographic activity. Changing the location of the task from the distance of the upper limb length and eye level to a location about 10 cm lower and 10 cm closer to the subject reduced the electromyographic activity of the trapezius muscles by 25-30%.
23.5.16 (125646) Brown, R T, Page, G B and McMahan, PB 'A biomechanical evaluation of railroad car hand brake operating methods' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety III Taylor & Francis, London (1991) pp 405-412 (6 refs) Current hand brake operating methods were evaluated to determine which methods allow workers to apply maximum force to the brake wheel while satisfying NIOSH criteria for back compression and strength capability. Three types of hand brake and two operating methods for each brake type were studied. Factors affecting the worker's operating posture were also considered in the analysis. Evaluation criteria were NIOSH Action Limits for back compression and strength capability. Maximum hand force for 64 different operating postures were determined using the University of Michigan 3D Static Strength Prediction ProgramTM. Preferred operating methods for each type of hand brake are presented, limitations of the methodology are identified, and plans for subsequent research are discussed.
23.5.15 (125642) Buchholz, B and Armstrong, T J 'An ellipsoidal representation of human hand anthropometry' Hum Factors Vol 33 No 4 (1991) pp 429-441 (6 refs) The goal of this study was to collect anthropometric data that describe the geometry of the surface of the hand and to model this anthropometry as a function of gross external hand measurements. The depth and breadth of each segment of the hand were measured at points that were spaced at approximately equal distances between the joints of the hand. Linear models using hand breadth as the independent variable explained from 12% to 47% of the variation in segment breadths and from 6% to 74% in segment depths. Ellipsoids are used in biomechanical models as an efficient mathematical description of the shape of kinematic segments for use in the determination of contact with other objects. Therefore the primary objectives of this study were to approximate the semi-axis dimension for these hand segment contact bodies using a linear model of the gross anthropometry and to evaluate the accuracy with which ellipsoids describe the geometry of the hand segments. Graphical components showed that differences between the ellipsoidai approximations and the breadth and depth measurements were
Vol 23 No 5 O c t o b e r 1992
23.5.17 (125653) Kumar, S, Phan, Q, Perry, P and Garand, D 'Push-pull strength at three heights' in Karwowski, W and Yates, J W (eds) Advances in industrial ergonomics and safety III Taylor & Francis, London (1991) pp 225-230 (12 refs) Ten young males and ten young females (mean age 21.1 years) were required to perform sagittally symmetrical maximal isometric and isokinetic push and pull exertion at 35 cm, 100 cm, and 150 cm height. Subjects performed these activities with their lower extremities (hip down) stabilized in a custom-designed device. The 12 experimental conditions were randomized. The strength was measured through a SM500 load cell in a specially designed strength tester. The collected data were fed on line to an IBM XT through a Metrabyte DAS 29 at a sampling rate of 50 Hz. The results revealed greatest strength in isometric pulling at 100 cm height. The isometric pushing strengths ranged between 41 and 68% and 27 to 44% for males and females respectively. The isokinetic
strengths were significantly lower than isometric strength (p < 0.Ol). The findings of the study suggest that jobsimulated appropriate gender-adjusted isokinetic strength should be used for job design. 23.5.18 (125681) Aykin, N M and Aykin, T 'Individual differences in humancomputer interaction' Comput Ind Eng Vol 20 No 3 (1991) pp 373-379 (50 refs) A comprehensive review of studies involving individual differences in human-computer interaction is presented. Past studies have revealed that certain user characteristics and user performance and preferences might be significantly related. In this review, user characteristics are classified into four groups: level of experience, personality traits, demographic characteristics and others. User characteristics that may affect user performance are discussed along with the advantages of incorporating them into human-computer interfaces. 23.5.19 (125685) Pocius, K E 'Personality factors in human-computer interaction: a review of the literature' Comput Human Behav Vol 7 No 3 (1991) pp 103-135 (76 refs) This is a review of studies investigating the relation between personality dimensions and human-computer interaction. The review is divided into three topic areas: programming aptitude and achievement, the programmer personality, and computer-assisted instruction (CAI). It is concluded as follows. (a) Introversion-extraversion and traits characterizing introversion-extraversion are related to many aspects of human-computer interaction. (b) There is little evidence to support a relation between the Jungian personality dimensions and programming aptitude and achievement. (c) Further, no correlations are reported between these dimensions and academic achievement in CAI-based courses; however, certain Jungian dimensions are related to attrition rate and speed of completion. (d) Although little relation between Jungian dimensions and programming aptitude and achievement is noted, certain personality types select careers that utilize computer programming. (e) Anxiety characterized by a threat to self-esteem facilitates or debilitates CAI performance contingent on specific aspects of the learning task. (f) Compulsive and stress-induced personality traits, internal-external locus of control, and achievement motivation are implicated in human-computer interaction performance.
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