Perceptualand Motor Skills, 1991, 73, 695-700.
63 Perceptual and Motor Skills 1991
SEX DIFFEREYCES I N PERFORMANCE O N A COMBINED MANUAL AND DECISION TASK ' ABDUR RAHIM AND BASU SHARMA University
of New Brunswick
Summary.-This report describes results of an experimental study of the differences in response time between 10 male and 10 female undergraduate operators performing a combined manual and decision task. Analysis indicated that the performance times of women on such tasks were shorter than those of the men as expected.
There is a significant amount of research pertaining to the effect of sex on performance. For example, Rosenthal (1978), Lind and Connole (1985), and Nelson, Thomas, Nelson, and Abraham (1986) studied sex differences in the performance of manual and mental tasks. York and Biederman (1990) investigated the effect of sex on ,reciprocal tapping performance. Thomas and French (1985, 1987) and Walker and Fennell (1986) summarized some findings pertaining to significant sex differences in such motor performances as balance, dash, grip strength, catching, long jump, vertical jump, shuttle run, and sit-ups. That females are slower than males in movement time, whereas males are slower than females in reaction time, is the general conclusion mentioned by investigators of performance behaviour (Henry, 1961; Hodgkins, 1963; Pierson & Lockhart, 1964; Bell, Ross, & John, 1982; Walker & Fennell, 1986). More specifically, some of these studies on the relationship between speed of reaction and of movement by the two sexes have concluded that men maintained the peak speed longer in movement while women maintained the peak speed longer during reaction. According to the study conducted by Drinkwater (1968), initially women were more accurate than men and gained in speed with experience. However, men responded more quickly during trials and improved in accuracy as trials were continued. Several other studies of reaction time in relation to sex have been investigated by Noble, Baker, and Jones (1964), and Welford (1980, Chap. 9). I n the past considerable efforts have been devoted to the study of performance of a combined manual and decision task (Thomas, Hancock, & Chaffin, 1974; Raouf & Mehra, 1974; Raouf & Arora, 1980; Rahim & Raouf, 1983). A combined manual and decision task may be viewed as one o n which the operator is required to use psychomotor skills as well as decision-making capabilities. While the past research has examined sex dif-
'Address correspondence to Basu Sharma, Faculty of Administration, University of New Brunswick, Fredericton, N.B., Canada E3B 5A3.
696
A. RAHIM & B. SHARMA
ferences in the performance of manual and mental tasks separately, such differences in performance on a combined manual and decision task have not yet been investigated. However, given that an increasing pace of technological change accompanied by automation has altered the contents of many traditional jobs, more workers need to perform combined manual and decision tasks these days. Also, as participation by women in the labour force continues to increase, sex differences in the performance of such tasks will have an important bearing on the debate concerning equity in pay. The purpose of this paper is to provide some empirical evidence, obtained from an experimental study, relating to the questions raised above.
METHOD The study defined a combined manual and decision task as one on which the sequence of motions performed by a worker changed or was likely to change from one cycle to another (Thomas, et al., 1974). The uncertainty regarding changes in the sequence was based upon the decisions that the worker made during each cycle. The choice of uncertainty or information load and magnitude of element reach were significant variables affecting the performance time (Raouf & Mehra, 1974; Raouf & Arora, 1980). The objective was to examine the performance differences between males and females when subjected to three levels of information load and three distances of reach.
Subjects The sample constituted ten men and ten women. They were selected nonsystematically from a university campus during one of the summer school sessions. The mean age of the men was 24.7 yr. and of the women 23.2 yr. All subjects admitted to being right-handed when asked prior to the experiment. Participation was solely on a volunteer basis. Instruments and Apparatus A Hewlett Packard Timer-Counter (Model 532A) was employed as a means of measuring performance times in milliseconds. To provide a completely random appearance of stimuli, a Slo-syn Tape Reader, manufactured by the Superior Electric Company, Bristol, Connecticut, was used. A United Systems Corporation Punch Controlled (Digitec Tape Punch) recorded performance times on paper tape. The stimulus-response (S-R) unit consisted of an horizontal row of eight white-illumination lights, each of which was paired with a push button, which, when depressed, switched off the corresponding light. Directly in front and to the centre of the row of lights was located an "initiation button" which, when depressed, illuminated one of the eight lights. The onset of one of these lights was considered to be a random event. And, the initiation button could be positioned on the centre line of the stimulus-response
677
SEX DIFFERENCES ON MANUAL DECISION TASK
\
0000 0000 4'
3'
1'
2'
1
2
3
4
1
2
3
4
RESPONSE SWITCHES 1 -
OUOU 4'
9'
2'
1'
INITIATION BUTTONS
1
7 in. = R, Position
I1
10 in. = R, Position
111
14 i n = R, Position
FIG. 1. Panel of lights and switches arranged horizontally relative to the initiation buttons at three reaches
unit from 7 to 14 inches away from the row of turn-off buttons. Fig. 1 exhibits these attributes of the instrument used for the study. Experimental Design Three levels of information load (H) were studied. The index of difficulty for each task was measured according to Fitts' Law (1954). The information load (H) was measured in units called bits (abbreviated from binary digits) (Fitts & Posner, 1967). For H, (1 bit) lights No. 1 and 1' were switched on randomly, for H, (2 bits) lights No. 1, l', 2, and 2' were used, and lights No. 1, l', 2, 2', 3 , 3', 4, and 4' provided for H, (3 bits). Each in-
698
A. RAHIM & B. SHARMA
formation-load condition was paired with three reaches, R,, R,, and R,, which corresponded to 7, 10, and 14 in., respectively. Each subject performed 100 cycles when under the condition of 1 bit, 200 cycles under 2 bits, and 400 cycles under 3 bits. Thus 2,100 data points were collected for each person. The use of different numbers of trials in each load condition was adopted to equalize the number of times each light was used as a stim,dus across the load conditions. The data were analyzed by collapsing across stimulus lights. It should be noted that the experimental design was completely randomized.
Procedure Each subject was shown 400 practice cycles prior to actual data cohection. In addition, each subject performed 40 practice trials before each changed condition to adapt to that condition. The subject's task was to (a) press the initiation button with the right-hand index finger. One of the lights would then be illuminated. Each subject knew the set of lights involved in each case. Also, (b) the subject was to move the same index finger as quickly as possible to switch off the light by depressing the appropriate button. Elapsed, time between the light onset and offset was recorded.
RESULTSAND DISCUSSION .
The mean time values and standard deviations for men and women for three reaches and information-load levels are presented in Table 1. These data indicate that women exhibited a faster performance than men and that the times for the three information loads and reaches were significantly different for the two sexes. For a given reach, the difference in performance time increases as inforTABLE 1 MEANTIMEVALUES(MsEc.) FORTHREEREACI-IES A N D INFORMATION LOADS Information
Load
Reach
Reach 1
Reach 3
2
M
SD
M
SD
M
SD
489 562 655 569
19 36 43
507 567 660 578
36 15 18
522 586 662 590
12 04 21
Men 1 2 3
M SD
95
74
59
Women 1 2 3
M SD
477 571 598 531
11 13 14
148
498 538 607 548
14 05 19 43
501 546 612 553
22 15
30
51
699
S E X DIFFERENCES ON MANUAL DECISION TASK
mation load increases. The difference in performance time at one given information load and different reaches does not seem to increase consistently. However, the results indicate that the performance times of women are shorter than those of men. Analysis of variance performed on the data confirms this. The interaction between sex, information load, and reach was significant ( p < .05); however, the interactions between sex and information load, sex and reach, or information load and reach were not significant. An increasing complexity of production systems associated with rapid technological change has greatly transformed the job content in industrialized countries. In numerous industrial situations, workers are required simultaneously to use their manual as well as decision-making capabilities. To simulate the work environment realistically, this study incorporated combined manual and decision task so possible differences in performance associated with the sex of the subject could be observed. Our findings suggest that women are in part faster than men in the performance of such a combined task.
a
REFERENCES BELL, I? A,, ROSS, L. J., & JOHN,C . C . (1982) Effects of heat, social facibtation. sex differences, and task difficulty on reaction time. Human Factors, 24, 19-24. DRINKWATER, B. L. (1968) Speed and accuracy in decision response of men and women pilots. Ergonomics, 11, 61-67. F I ~ S I?, M. (1954) The information ca acity of the human motor system in controlling the amplitude of movement. lournal oP~xperimenialPsychology, 47, 381-391. F m s , P. M., & POSNER,M. I. (1967) Human performance. Belmont, CA: Wadsworth. HENRY,F, M . (1961) Stimulus complexity, movement complexity, age, and sex in relation to reaction latency and speed in limb movements. Research Quarterly, 32, 353-366. HODGKTNS, J. (1963) Reaction time and speed movement in males and females o l various ages. Research Quarterly, 34, 335-343. L ~ DP.,, & CONNOLE,H. (1985) Sex differences in behavioral and cognitive aspects of decision control. Sex Roles, 12, 813-823. K., THOMAS,J., NELSON,K. R., & ABRAHAM,P. C. (1986) Gender differences in NELSON;Lildren's throwing performance: biology and environment. Research Quarterly, 57, 280287.
NOBLE,C. E., BAKER,B. L., &JONES, T. A. (1964) Age and sex parameters in psychomotor learning. Perceplual and Motor Skills, 19, 935-945. PIERSON,W. R., & LOCKHART,A. (1964) Fatigue, work decrement and endurance of women in a simple repetitive task. Aerorpace Medicine, 35, 724-725. RAHLM,M. A , , & h o r n , A. (1983) Modelling human performance reliability in a two stage combined manual and decision cask. Microelectronics Reliability, 23, 1131-1141. RAOUF,A,, & ARORA,S. (1980) Effect of informational load, index of diEficulty, direction and plane angles of discrete moves in a combined manual and decision task. International Joztrnal of Production Research, 18, 117-128. h o w , A , , & MEHRA,R. (1974) Experimental investigations related to combined manual and decision tasks. International Journal of Production Research, 12, 151-157. ROSENTHAL,S. F. (1978) The relationshi of attraction and sex composition to performance and non-performance: experimentafoutcomes in dyads. Sex Roles, 4, 887-898. THOMAS,J. R., & FRENCH,K. E. (1985) Gender differences across age in motor performance: a meta-analysis. Psychological Bulletin, 98, 260-282. TI-IOMAS, J. R., & FRENCH,K. E. (1987) References lor motor tasks-gender differences across age in motor performance: a meta-analysis. Percephurl and Motor Skills, 64, 503-506.
700
A. RAHIM & B. SHARMA
THOMAS, M. U., HANCOCK, W.M., & CHAFFIN,D. B. (1974) Performance of a combined manual and decision task with discrete uncertainty. International Journal of Production Research, 12, 409-426. WALKER, H. A., & FENNELL, M. L. (1986) Gender differences in role differentiation and organAnnual Review of Sociology, 12, 255-275. izational task WELFORD, A. T. (1980) Reaction times. London: Oxford Univer. Press. YORK,J. L., & BIEDERMAN, I. (1990) Effects of age and sex on reciprocal tapping performance. Perceptual and Motor Skills, 7 1, 675-684. Accepted October 15, 1991.
63 Perceptual and Motor Skills 1991
SEX DIFFEREYCES I N PERFORMANCE O N A COMBINED MANUAL AND DECISION TASK ' ABDUR RAHIM AND BASU SHARMA University
of New Brunswick
Summary.-This report describes results of an experimental study of the differences in response time between 10 male and 10 female undergraduate operators performing a combined manual and decision task. Analysis indicated that the performance times of women on such tasks were shorter than those of the men as expected.
There is a significant amount of research pertaining to the effect of sex on performance. For example, Rosenthal (1978), Lind and Connole (1985), and Nelson, Thomas, Nelson, and Abraham (1986) studied sex differences in the performance of manual and mental tasks. York and Biederman (1990) investigated the effect of sex on ,reciprocal tapping performance. Thomas and French (1985, 1987) and Walker and Fennell (1986) summarized some findings pertaining to significant sex differences in such motor performances as balance, dash, grip strength, catching, long jump, vertical jump, shuttle run, and sit-ups. That females are slower than males in movement time, whereas males are slower than females in reaction time, is the general conclusion mentioned by investigators of performance behaviour (Henry, 1961; Hodgkins, 1963; Pierson & Lockhart, 1964; Bell, Ross, & John, 1982; Walker & Fennell, 1986). More specifically, some of these studies on the relationship between speed of reaction and of movement by the two sexes have concluded that men maintained the peak speed longer in movement while women maintained the peak speed longer during reaction. According to the study conducted by Drinkwater (1968), initially women were more accurate than men and gained in speed with experience. However, men responded more quickly during trials and improved in accuracy as trials were continued. Several other studies of reaction time in relation to sex have been investigated by Noble, Baker, and Jones (1964), and Welford (1980, Chap. 9). I n the past considerable efforts have been devoted to the study of performance of a combined manual and decision task (Thomas, Hancock, & Chaffin, 1974; Raouf & Mehra, 1974; Raouf & Arora, 1980; Rahim & Raouf, 1983). A combined manual and decision task may be viewed as one o n which the operator is required to use psychomotor skills as well as decision-making capabilities. While the past research has examined sex dif-
'Address correspondence to Basu Sharma, Faculty of Administration, University of New Brunswick, Fredericton, N.B., Canada E3B 5A3.
696
A. RAHIM & B. SHARMA
ferences in the performance of manual and mental tasks separately, such differences in performance on a combined manual and decision task have not yet been investigated. However, given that an increasing pace of technological change accompanied by automation has altered the contents of many traditional jobs, more workers need to perform combined manual and decision tasks these days. Also, as participation by women in the labour force continues to increase, sex differences in the performance of such tasks will have an important bearing on the debate concerning equity in pay. The purpose of this paper is to provide some empirical evidence, obtained from an experimental study, relating to the questions raised above.
METHOD The study defined a combined manual and decision task as one on which the sequence of motions performed by a worker changed or was likely to change from one cycle to another (Thomas, et al., 1974). The uncertainty regarding changes in the sequence was based upon the decisions that the worker made during each cycle. The choice of uncertainty or information load and magnitude of element reach were significant variables affecting the performance time (Raouf & Mehra, 1974; Raouf & Arora, 1980). The objective was to examine the performance differences between males and females when subjected to three levels of information load and three distances of reach.
Subjects The sample constituted ten men and ten women. They were selected nonsystematically from a university campus during one of the summer school sessions. The mean age of the men was 24.7 yr. and of the women 23.2 yr. All subjects admitted to being right-handed when asked prior to the experiment. Participation was solely on a volunteer basis. Instruments and Apparatus A Hewlett Packard Timer-Counter (Model 532A) was employed as a means of measuring performance times in milliseconds. To provide a completely random appearance of stimuli, a Slo-syn Tape Reader, manufactured by the Superior Electric Company, Bristol, Connecticut, was used. A United Systems Corporation Punch Controlled (Digitec Tape Punch) recorded performance times on paper tape. The stimulus-response (S-R) unit consisted of an horizontal row of eight white-illumination lights, each of which was paired with a push button, which, when depressed, switched off the corresponding light. Directly in front and to the centre of the row of lights was located an "initiation button" which, when depressed, illuminated one of the eight lights. The onset of one of these lights was considered to be a random event. And, the initiation button could be positioned on the centre line of the stimulus-response
677
SEX DIFFERENCES ON MANUAL DECISION TASK
\
0000 0000 4'
3'
1'
2'
1
2
3
4
1
2
3
4
RESPONSE SWITCHES 1 -
OUOU 4'
9'
2'
1'
INITIATION BUTTONS
1
7 in. = R, Position
I1
10 in. = R, Position
111
14 i n = R, Position
FIG. 1. Panel of lights and switches arranged horizontally relative to the initiation buttons at three reaches
unit from 7 to 14 inches away from the row of turn-off buttons. Fig. 1 exhibits these attributes of the instrument used for the study. Experimental Design Three levels of information load (H) were studied. The index of difficulty for each task was measured according to Fitts' Law (1954). The information load (H) was measured in units called bits (abbreviated from binary digits) (Fitts & Posner, 1967). For H, (1 bit) lights No. 1 and 1' were switched on randomly, for H, (2 bits) lights No. 1, l', 2, and 2' were used, and lights No. 1, l', 2, 2', 3 , 3', 4, and 4' provided for H, (3 bits). Each in-
698
A. RAHIM & B. SHARMA
formation-load condition was paired with three reaches, R,, R,, and R,, which corresponded to 7, 10, and 14 in., respectively. Each subject performed 100 cycles when under the condition of 1 bit, 200 cycles under 2 bits, and 400 cycles under 3 bits. Thus 2,100 data points were collected for each person. The use of different numbers of trials in each load condition was adopted to equalize the number of times each light was used as a stim,dus across the load conditions. The data were analyzed by collapsing across stimulus lights. It should be noted that the experimental design was completely randomized.
Procedure Each subject was shown 400 practice cycles prior to actual data cohection. In addition, each subject performed 40 practice trials before each changed condition to adapt to that condition. The subject's task was to (a) press the initiation button with the right-hand index finger. One of the lights would then be illuminated. Each subject knew the set of lights involved in each case. Also, (b) the subject was to move the same index finger as quickly as possible to switch off the light by depressing the appropriate button. Elapsed, time between the light onset and offset was recorded.
RESULTSAND DISCUSSION .
The mean time values and standard deviations for men and women for three reaches and information-load levels are presented in Table 1. These data indicate that women exhibited a faster performance than men and that the times for the three information loads and reaches were significantly different for the two sexes. For a given reach, the difference in performance time increases as inforTABLE 1 MEANTIMEVALUES(MsEc.) FORTHREEREACI-IES A N D INFORMATION LOADS Information
Load
Reach
Reach 1
Reach 3
2
M
SD
M
SD
M
SD
489 562 655 569
19 36 43
507 567 660 578
36 15 18
522 586 662 590
12 04 21
Men 1 2 3
M SD
95
74
59
Women 1 2 3
M SD
477 571 598 531
11 13 14
148
498 538 607 548
14 05 19 43
501 546 612 553
22 15
30
51
699
S E X DIFFERENCES ON MANUAL DECISION TASK
mation load increases. The difference in performance time at one given information load and different reaches does not seem to increase consistently. However, the results indicate that the performance times of women are shorter than those of men. Analysis of variance performed on the data confirms this. The interaction between sex, information load, and reach was significant ( p < .05); however, the interactions between sex and information load, sex and reach, or information load and reach were not significant. An increasing complexity of production systems associated with rapid technological change has greatly transformed the job content in industrialized countries. In numerous industrial situations, workers are required simultaneously to use their manual as well as decision-making capabilities. To simulate the work environment realistically, this study incorporated combined manual and decision task so possible differences in performance associated with the sex of the subject could be observed. Our findings suggest that women are in part faster than men in the performance of such a combined task.
a
REFERENCES BELL, I? A,, ROSS, L. J., & JOHN,C . C . (1982) Effects of heat, social facibtation. sex differences, and task difficulty on reaction time. Human Factors, 24, 19-24. DRINKWATER, B. L. (1968) Speed and accuracy in decision response of men and women pilots. Ergonomics, 11, 61-67. F I ~ S I?, M. (1954) The information ca acity of the human motor system in controlling the amplitude of movement. lournal oP~xperimenialPsychology, 47, 381-391. F m s , P. M., & POSNER,M. I. (1967) Human performance. Belmont, CA: Wadsworth. HENRY,F, M . (1961) Stimulus complexity, movement complexity, age, and sex in relation to reaction latency and speed in limb movements. Research Quarterly, 32, 353-366. HODGKTNS, J. (1963) Reaction time and speed movement in males and females o l various ages. Research Quarterly, 34, 335-343. L ~ DP.,, & CONNOLE,H. (1985) Sex differences in behavioral and cognitive aspects of decision control. Sex Roles, 12, 813-823. K., THOMAS,J., NELSON,K. R., & ABRAHAM,P. C. (1986) Gender differences in NELSON;Lildren's throwing performance: biology and environment. Research Quarterly, 57, 280287.
NOBLE,C. E., BAKER,B. L., &JONES, T. A. (1964) Age and sex parameters in psychomotor learning. Perceplual and Motor Skills, 19, 935-945. PIERSON,W. R., & LOCKHART,A. (1964) Fatigue, work decrement and endurance of women in a simple repetitive task. Aerorpace Medicine, 35, 724-725. RAHLM,M. A , , & h o r n , A. (1983) Modelling human performance reliability in a two stage combined manual and decision cask. Microelectronics Reliability, 23, 1131-1141. RAOUF,A,, & ARORA,S. (1980) Effect of informational load, index of diEficulty, direction and plane angles of discrete moves in a combined manual and decision task. International Joztrnal of Production Research, 18, 117-128. h o w , A , , & MEHRA,R. (1974) Experimental investigations related to combined manual and decision tasks. International Journal of Production Research, 12, 151-157. ROSENTHAL,S. F. (1978) The relationshi of attraction and sex composition to performance and non-performance: experimentafoutcomes in dyads. Sex Roles, 4, 887-898. THOMAS,J. R., & FRENCH,K. E. (1985) Gender differences across age in motor performance: a meta-analysis. Psychological Bulletin, 98, 260-282. TI-IOMAS, J. R., & FRENCH,K. E. (1987) References lor motor tasks-gender differences across age in motor performance: a meta-analysis. Percephurl and Motor Skills, 64, 503-506.
700
A. RAHIM & B. SHARMA
THOMAS, M. U., HANCOCK, W.M., & CHAFFIN,D. B. (1974) Performance of a combined manual and decision task with discrete uncertainty. International Journal of Production Research, 12, 409-426. WALKER, H. A., & FENNELL, M. L. (1986) Gender differences in role differentiation and organAnnual Review of Sociology, 12, 255-275. izational task WELFORD, A. T. (1980) Reaction times. London: Oxford Univer. Press. YORK,J. L., & BIEDERMAN, I. (1990) Effects of age and sex on reciprocal tapping performance. Perceptual and Motor Skills, 7 1, 675-684. Accepted October 15, 1991.
