Perceficual and Motor Skills, 1976,42, 983-988. @ Prcceptual and Motor Skills 1976
PREFERRED H A N D A N D STEADINESS OF REACTION TIME R. NAKAMURA, R. TANIGUCHI, AND Y. OSHIMA Tokyo Metropolitan Institute for Neuroscience? Summary.-RT and its left/right difference of both biceps muscles were measured by electromyogram (EMG) in the bilateral sirnulcaneous flexion of elbows using 11 left- and 13 right-handed subjects under four conditions which were combinations of two factors: warning signal; presence or absence of a forrperiod, and position of limbs; elbow 90" or 135". EMG-RT and irs left/right difference were influenced by these factors. The effects of warning and position of limbs were not the same on the preferred and non-preferred hands. It was assumed that EMG-RTs of biceps in che preferred hand were less influenced by these experimental conditions.
Experiments using reaction time have often been utilized to determine the dominance of one hand over the other. Kerr, Mingay, and Elithorn (1963) reported that responses made by the preferred hand were, on the average, faster than those done by the non-preferred hand, whereas others (Benton & Joynt, 1958; Dimond, 1970) stated that the small differences in response times between one hand and the other had generally failed to reach appropriate levels of statistical significance. Thus, the relationship berween handedness and R T is still open to doubt. Recently we reported some results about the mirrorimage in differences of RTs of left and right hands or synchronization error between left-handed and right-handed subjects (Nakamura & Saito, 1974; Nakamura, Taniguchi, & Oshima, 1975). Several studies have shown that the stretching or shortening of muscles and position changes in the joints influence RT (Smith & Whitley, 1964; Nakamura & Viel, 1974). In this paper we attempted to investigate how changes in the elbow angle and the presence or absence of a warning signal influence RTs of biceps muscles and whether there are some differences in response between the preferred and non-preferred hands. METHOD Experiments were performed on 24 normal subjects. Eleven subjects, 5 males and 6 females (27.9 f 6.5 yr.), who were predominantly left-handed and 13, 7 males and 6 females (30.6 + 6.5 yr.), predominantly right-handed were selected on the basis of having consistent laterality preferences on the test of laterality previously described (Nakamura & Saito, 1974). In a quiet room the subject, with eyes closed, was seated in a comfortable posture on-a chair with the trunk upright and slightly pronated forearms placed on supports which could be adjusted to modify the angle of elbow joints. Shoulders remained in a neutral position and wrists in slight flexion (Fig. 1). 'Department of Rehabilitation.
R NAKAMURA, ET AL.
FIG. 1. Subject in position for test (Elbow 90") The subject was asked to respond to a peep sound (1000 Hz, about 100 db, 100 msec.) with a rapid bilateral flexion of both elbows under four conditions which were combinations of two factors, warning signal and position of limbs; ( 1 ) elbow 90' with warning, ( 2 ) elbow 135" with warning, ( 3 ) elbow 90" without warning, and (4) elbow 135" without warning (full extension of elbow = 180"). In 'with warning' the stimulus was presented 3 to 4 sec. after a warning "Yoi (ready)" and trial interval was about 20 sec. In 'without warning' trial interval was randomly varied within a range of 15 to 60 sec., rhus avoiding subject's prediction of response timing. The conditions were changed after every five trials in random order. The number of trials were 10 in each condition for a total of 40. Before the experimental run several trials were performed to acquaint the subject thoroughly with the procedure. Surface electrodes were placed on both biceps muscles. The electromyograms (EMG) were recorded through AC amplifiers (time constant 0.001 sec.) and displayed on a memoscope equipped in an average computer (ATAC 501-10, Nihonkhoden). The record was analyzed by measuring the distance between the point on EMG tracing where the stimulus began and the point of first electrical activity with a millisecond scale. The EMG latency thus measured will be referred to as EMG-RT which corresponds to pre-motor reaction time, and left/right difference of EMG-RT will be defined to give a faster EMGRT in the right hand, a positive value, and vice versa for each trial. RESULTSAND DISCUSSION The means and standard errors of EMG-RTs and left/right differences under f o ~ uconditions are presented in Table 1. Comparing SEs of EMG-RTs and left/right differences between left- and right-handed subjects, the significant F ratio was observed except SE of left/right difference at elbow 135' without
PREFERRED HAND AND STEADINESS TABLE 1 MEANSAND STANDARD ERRORS OF EMG-RTS (MSEC.)
AND
LEPT/RIGHT DIFFERENCES
Left-handed subjects left riaht I/r With warning Elbow 90"
985
R~ghthanded subjects left right I/r
M
SE Elbow 135"
M
SE Without warning Elbow 90'
M
SE Elbow 135"
M
SE warning (Table 2 ) . SEs of EMG-RTs of both biceps muscles and those of left/right differences were generally larger in the left-handed subjects than in the right-handed ones. From the viewpoint of EMG-RT and left/right difference, data for the left-handed subjects were not so homogeneous as those for the right-handed ones, so that the results were respectively dealt with in the left- and right-handed subjects. TABLE 2 P RAno OF SEs BETWEEN LEFT- AND RIGHT-HANDEDSUB JE~TS left
right
With warning 6.04 6.23 Elbow 90" Elbow 135" 3.13 3.54 Without warning 4.97 5.11 Elbow 90" Elbow 135" 3.61 3.82 Note.-Significant P ratios are 2.76 at 5% level and 4.30 at 1% (df=
l/r
3.35 2.35 4.43 1.80 10/12).
As can be seen in Table 3 EMG-RT of the non-preferred hand was faster than that of the preferred hand both for the left- and right-handed subjects. EMG-RTs were faster under 'with warning' than under 'without warning' and also faster at elbow 135' than at 90°. The fastest EMG-RT was obtained at elbow 135' with warning and the slowest at 90' without warning. Slower EMG-RTs under 'without warning' were due to subject's uncertainty about the time of stimulus occurrence ( ~ l e m m e r ,1956). Concerning factors of faster EMG-RTs at 135' than at 90°, there are two possibilities, peripheral and central mechanisms. According to Smith and Whitley (1964), reaction time
986
R. NAKAMURA, ET AL.
TABLE 3
ANALYSIS OF VARIANCEOF EMG-RTs df Hand Warning H X W Position of Limbs H X P W X P H x W X P Subject H X S wXS H X W X S F X S H X P X S W X P X S H X W X P X S Error Total * p < .05.
Left-handed subjects MS F
1 1584.00 1 247104.06 1 464.00 1 28048.00 1 848.00 1 128.00 1 224.00 10 101740.81 10 67.20 10 5630.40 10 12.80 10 3574.40 10 16.00 10 672.00 10 30.40 792 75.82 879
23.57* 43.88' 36.25* 7.84* 53.00* 0.19 7.36* 1341.87*
Right-handed subjects
df
MS
1 1388.00 1 108386.05 1 335.00 1 15084.00 1 483.00 1 79.00 1 133.00 12 22950.66 12 22.33 12 3059.16 12 1.41 12 649.66 12 2.41 12 442.75 12 19.91 936 21.11 1039
F 62.15* 35.42* 237.58* 23.21* 200.41* 0.17 6.68* 1087.18*
following stretching of the prime movers is significantly faster than normal R T due to the action of some mechanisms involved in neuromuscular transmission which is significantly facilitated by stretch. Also, our results are in keeping with those of Gellhorn (1949) in his work on stimulation of the motor cortex in the monkey in different conditions of fixation of elbow joint. Studying the reactivity of arm muscles including biceps in order to elucidate the role of proprioceptive impulses in cortically induced movements, he showed that the fixation of elbow at an obtuse angle greatly increased the response of biceps, both amplitude of EMG and summation time, to cortical stimulation. The interactions of Hand X Warning, Hand X Position of limbs, and H X W X P were significant. The effects of warning and position of limbs were not the same for the preferred and non-preferred hands both in the leftand right-handed subjects. Shifts of EMG-RT at elbow 135' with warning from that at elbow 90' without warning were 41.5 msec. in the preferred hand and 48.1 msec. in the non-preferred hand of the left-handed subjects, and 25.6 msec., 30.4 msec. in the right-handed subjects respectively. The question, whether or not the difference in shifts of EMG-RT between the preferred and non-preferred hands was statistically significant, was tested by a comparison of left/right difference among four conditions (Table 4 ) . These differences in EMG-RTs showed the reversed pattern between the left-handed and righthanded subjects, although there was no significant difference for the absolute
987
PREFERRED HAND AND STEADINESS TABLE 4 COMPARISONS OP LEPT/RIGHT DIFFERENCES
Elbow 90" with warning vs 135" with warning vs 90" without warning vs 135" without warning Elbow 135" with warning vs 90" without warning vs 135" without warning Elbow 90' without warning vs 135" without warning
* p < 0.05. Note.-The
Left-handed
Right-handed
-1 1.67* 0.17 1.72
13.86* 0.62 - 1.55
-1 1.80* - 8.58'
14.95* 12.71*
-
-
2.22*
2.01*
--
value ( I ) is given with 1 = Z t/&,
number of subjects.
~ 1 ,
values in each pair (Cochran-Cox, t' = 0.126 to 1.356, df = 12). There were significant left/right differences between elbow 90' and 135' positions, either with or without warning. At elbow 135' the significant difference was observed between 'with warning' and 'without warning.' N o significant difference could be detected at elbow 90' between 'with warning' and 'without warning.' The difference between EMG-RT of the preferred and non-preferred hands at elbow 135' with warning was considerable, whereas in the other three conditions it was rather small. These results suggest that the shift of EMG-RTs in the preferred hand through changes in elbow angle was not parallel to that of the non-preferred hand, because if shifts of EMG-RTs in both hands were parallel, left/right differences between hands of either positions should be the same. Thus, the shift of EMG-RTs in the non-preferred hand through changes in elbow angle was greater, especially in the response preceded by a warning signal. The present results emphasize the dependency of EMG-RT of the biceps on position of the limb and experimental conditions. Changes in the angle of the elbow joint had a significant effect upon EMG-RT and its difference between hands. It was assumed that EMG-RT of the preferred hand was less influenced by changes in position of the limb. Dimond (1972) stated that differences between the hands are unlikely to be observed in simple movement patterns, simple tests of muscle strength and accuracy of the reproduction of pressure. According to Simon ( 1964), hand steadiness, measured by a Standard Steadiness Test, cannot be regarded as a sensitive index of handedness. Using simple movement pattern, however, the consistency of EMG-RTs in the preferred hand was clearly observed in our experiment. It is important to note the dependency of the difference between hands in EMG-RT on position of the limb as well as the presence or absence of a warning signal. Also, we should like to draw attention to the large individual differences
988
R NAKAMURA, ET AL.
in EMG-RTand its left/right difference for left-handed subjects. These findings were also compatible with our previous work on synchronization error in bilateral simultaneous flexion of elbows (Nakamura, Taniguchi, & Oshima,
1975) . REFERENCES BENTON, A. L,& JOYNT, R. J. Reaction time in unilateral cerebral disease. Confin. N w o l . , 1958, 19, 247-256. DWOND, S. Hemispheric refractoriness and the control of reaction time. Q u d . J . exp. Psychol., 1970, 24, 610-617. D m o m , S. T h e double b ~ a i n . London: Churchill Livingstone, 1972. GBLLHORN, E Proprioception and the motor cortex. Brain, 1949, 72, 35-62. KERR, M., MINGAY,R., & ELITHORN,A. Cerebral dominance in reaction time responses. Bsit. J. Psychol., 1963, 54, 325-336. KLEMMW, E. T. Time uncertainty in simple reaction time. J. exp. Psychol., 1956, 51, 179-184. NAKAMURA, R.,& SAITO, H. Preferred hand and reaction time in different movement patterns. Percept, mot. Shills, 1974, 39, 1275-1281. . NAKAMURA, R., TANIGUCHI,R., & OSHIMA,Y. Synchronization error in bilateral simultaneous flexion of elbows. Percept. mot. Skills, 1975, 40, 527-532. NAKAMURA,R., 8r VIEL, E. The influence of position changes in the proximal joint on EMG-recorded reaction time on key muscles in the human extremity. Pro. ceedings of 7th International Congress of World Confederation for Physical Therapy, Montreal, Canada, 1974. Pp. 119-123. SIMON, J. R. Steadiness, handedness, and hand preference. Percept. mot. Skills, 1964, 18, 203-206. SMITH, L. E., & WHIneY, J. D. Faster reaction time through facilitation of neuromuscular junctional transmission in muscles under maximal stretch. Percept. mot. Skills, 1964, 19, 503-509.
Accepted February 20,1976.
PREFERRED H A N D A N D STEADINESS OF REACTION TIME R. NAKAMURA, R. TANIGUCHI, AND Y. OSHIMA Tokyo Metropolitan Institute for Neuroscience? Summary.-RT and its left/right difference of both biceps muscles were measured by electromyogram (EMG) in the bilateral sirnulcaneous flexion of elbows using 11 left- and 13 right-handed subjects under four conditions which were combinations of two factors: warning signal; presence or absence of a forrperiod, and position of limbs; elbow 90" or 135". EMG-RT and irs left/right difference were influenced by these factors. The effects of warning and position of limbs were not the same on the preferred and non-preferred hands. It was assumed that EMG-RTs of biceps in che preferred hand were less influenced by these experimental conditions.
Experiments using reaction time have often been utilized to determine the dominance of one hand over the other. Kerr, Mingay, and Elithorn (1963) reported that responses made by the preferred hand were, on the average, faster than those done by the non-preferred hand, whereas others (Benton & Joynt, 1958; Dimond, 1970) stated that the small differences in response times between one hand and the other had generally failed to reach appropriate levels of statistical significance. Thus, the relationship berween handedness and R T is still open to doubt. Recently we reported some results about the mirrorimage in differences of RTs of left and right hands or synchronization error between left-handed and right-handed subjects (Nakamura & Saito, 1974; Nakamura, Taniguchi, & Oshima, 1975). Several studies have shown that the stretching or shortening of muscles and position changes in the joints influence RT (Smith & Whitley, 1964; Nakamura & Viel, 1974). In this paper we attempted to investigate how changes in the elbow angle and the presence or absence of a warning signal influence RTs of biceps muscles and whether there are some differences in response between the preferred and non-preferred hands. METHOD Experiments were performed on 24 normal subjects. Eleven subjects, 5 males and 6 females (27.9 f 6.5 yr.), who were predominantly left-handed and 13, 7 males and 6 females (30.6 + 6.5 yr.), predominantly right-handed were selected on the basis of having consistent laterality preferences on the test of laterality previously described (Nakamura & Saito, 1974). In a quiet room the subject, with eyes closed, was seated in a comfortable posture on-a chair with the trunk upright and slightly pronated forearms placed on supports which could be adjusted to modify the angle of elbow joints. Shoulders remained in a neutral position and wrists in slight flexion (Fig. 1). 'Department of Rehabilitation.
R NAKAMURA, ET AL.
FIG. 1. Subject in position for test (Elbow 90") The subject was asked to respond to a peep sound (1000 Hz, about 100 db, 100 msec.) with a rapid bilateral flexion of both elbows under four conditions which were combinations of two factors, warning signal and position of limbs; ( 1 ) elbow 90' with warning, ( 2 ) elbow 135" with warning, ( 3 ) elbow 90" without warning, and (4) elbow 135" without warning (full extension of elbow = 180"). In 'with warning' the stimulus was presented 3 to 4 sec. after a warning "Yoi (ready)" and trial interval was about 20 sec. In 'without warning' trial interval was randomly varied within a range of 15 to 60 sec., rhus avoiding subject's prediction of response timing. The conditions were changed after every five trials in random order. The number of trials were 10 in each condition for a total of 40. Before the experimental run several trials were performed to acquaint the subject thoroughly with the procedure. Surface electrodes were placed on both biceps muscles. The electromyograms (EMG) were recorded through AC amplifiers (time constant 0.001 sec.) and displayed on a memoscope equipped in an average computer (ATAC 501-10, Nihonkhoden). The record was analyzed by measuring the distance between the point on EMG tracing where the stimulus began and the point of first electrical activity with a millisecond scale. The EMG latency thus measured will be referred to as EMG-RT which corresponds to pre-motor reaction time, and left/right difference of EMG-RT will be defined to give a faster EMGRT in the right hand, a positive value, and vice versa for each trial. RESULTSAND DISCUSSION The means and standard errors of EMG-RTs and left/right differences under f o ~ uconditions are presented in Table 1. Comparing SEs of EMG-RTs and left/right differences between left- and right-handed subjects, the significant F ratio was observed except SE of left/right difference at elbow 135' without
PREFERRED HAND AND STEADINESS TABLE 1 MEANSAND STANDARD ERRORS OF EMG-RTS (MSEC.)
AND
LEPT/RIGHT DIFFERENCES
Left-handed subjects left riaht I/r With warning Elbow 90"
985
R~ghthanded subjects left right I/r
M
SE Elbow 135"
M
SE Without warning Elbow 90'
M
SE Elbow 135"
M
SE warning (Table 2 ) . SEs of EMG-RTs of both biceps muscles and those of left/right differences were generally larger in the left-handed subjects than in the right-handed ones. From the viewpoint of EMG-RT and left/right difference, data for the left-handed subjects were not so homogeneous as those for the right-handed ones, so that the results were respectively dealt with in the left- and right-handed subjects. TABLE 2 P RAno OF SEs BETWEEN LEFT- AND RIGHT-HANDEDSUB JE~TS left
right
With warning 6.04 6.23 Elbow 90" Elbow 135" 3.13 3.54 Without warning 4.97 5.11 Elbow 90" Elbow 135" 3.61 3.82 Note.-Significant P ratios are 2.76 at 5% level and 4.30 at 1% (df=
l/r
3.35 2.35 4.43 1.80 10/12).
As can be seen in Table 3 EMG-RT of the non-preferred hand was faster than that of the preferred hand both for the left- and right-handed subjects. EMG-RTs were faster under 'with warning' than under 'without warning' and also faster at elbow 135' than at 90°. The fastest EMG-RT was obtained at elbow 135' with warning and the slowest at 90' without warning. Slower EMG-RTs under 'without warning' were due to subject's uncertainty about the time of stimulus occurrence ( ~ l e m m e r ,1956). Concerning factors of faster EMG-RTs at 135' than at 90°, there are two possibilities, peripheral and central mechanisms. According to Smith and Whitley (1964), reaction time
986
R. NAKAMURA, ET AL.
TABLE 3
ANALYSIS OF VARIANCEOF EMG-RTs df Hand Warning H X W Position of Limbs H X P W X P H x W X P Subject H X S wXS H X W X S F X S H X P X S W X P X S H X W X P X S Error Total * p < .05.
Left-handed subjects MS F
1 1584.00 1 247104.06 1 464.00 1 28048.00 1 848.00 1 128.00 1 224.00 10 101740.81 10 67.20 10 5630.40 10 12.80 10 3574.40 10 16.00 10 672.00 10 30.40 792 75.82 879
23.57* 43.88' 36.25* 7.84* 53.00* 0.19 7.36* 1341.87*
Right-handed subjects
df
MS
1 1388.00 1 108386.05 1 335.00 1 15084.00 1 483.00 1 79.00 1 133.00 12 22950.66 12 22.33 12 3059.16 12 1.41 12 649.66 12 2.41 12 442.75 12 19.91 936 21.11 1039
F 62.15* 35.42* 237.58* 23.21* 200.41* 0.17 6.68* 1087.18*
following stretching of the prime movers is significantly faster than normal R T due to the action of some mechanisms involved in neuromuscular transmission which is significantly facilitated by stretch. Also, our results are in keeping with those of Gellhorn (1949) in his work on stimulation of the motor cortex in the monkey in different conditions of fixation of elbow joint. Studying the reactivity of arm muscles including biceps in order to elucidate the role of proprioceptive impulses in cortically induced movements, he showed that the fixation of elbow at an obtuse angle greatly increased the response of biceps, both amplitude of EMG and summation time, to cortical stimulation. The interactions of Hand X Warning, Hand X Position of limbs, and H X W X P were significant. The effects of warning and position of limbs were not the same for the preferred and non-preferred hands both in the leftand right-handed subjects. Shifts of EMG-RT at elbow 135' with warning from that at elbow 90' without warning were 41.5 msec. in the preferred hand and 48.1 msec. in the non-preferred hand of the left-handed subjects, and 25.6 msec., 30.4 msec. in the right-handed subjects respectively. The question, whether or not the difference in shifts of EMG-RT between the preferred and non-preferred hands was statistically significant, was tested by a comparison of left/right difference among four conditions (Table 4 ) . These differences in EMG-RTs showed the reversed pattern between the left-handed and righthanded subjects, although there was no significant difference for the absolute
987
PREFERRED HAND AND STEADINESS TABLE 4 COMPARISONS OP LEPT/RIGHT DIFFERENCES
Elbow 90" with warning vs 135" with warning vs 90" without warning vs 135" without warning Elbow 135" with warning vs 90" without warning vs 135" without warning Elbow 90' without warning vs 135" without warning
* p < 0.05. Note.-The
Left-handed
Right-handed
-1 1.67* 0.17 1.72
13.86* 0.62 - 1.55
-1 1.80* - 8.58'
14.95* 12.71*
-
-
2.22*
2.01*
--
value ( I ) is given with 1 = Z t/&,
number of subjects.
~ 1 ,
values in each pair (Cochran-Cox, t' = 0.126 to 1.356, df = 12). There were significant left/right differences between elbow 90' and 135' positions, either with or without warning. At elbow 135' the significant difference was observed between 'with warning' and 'without warning.' N o significant difference could be detected at elbow 90' between 'with warning' and 'without warning.' The difference between EMG-RT of the preferred and non-preferred hands at elbow 135' with warning was considerable, whereas in the other three conditions it was rather small. These results suggest that the shift of EMG-RTs in the preferred hand through changes in elbow angle was not parallel to that of the non-preferred hand, because if shifts of EMG-RTs in both hands were parallel, left/right differences between hands of either positions should be the same. Thus, the shift of EMG-RTs in the non-preferred hand through changes in elbow angle was greater, especially in the response preceded by a warning signal. The present results emphasize the dependency of EMG-RT of the biceps on position of the limb and experimental conditions. Changes in the angle of the elbow joint had a significant effect upon EMG-RT and its difference between hands. It was assumed that EMG-RT of the preferred hand was less influenced by changes in position of the limb. Dimond (1972) stated that differences between the hands are unlikely to be observed in simple movement patterns, simple tests of muscle strength and accuracy of the reproduction of pressure. According to Simon ( 1964), hand steadiness, measured by a Standard Steadiness Test, cannot be regarded as a sensitive index of handedness. Using simple movement pattern, however, the consistency of EMG-RTs in the preferred hand was clearly observed in our experiment. It is important to note the dependency of the difference between hands in EMG-RT on position of the limb as well as the presence or absence of a warning signal. Also, we should like to draw attention to the large individual differences
988
R NAKAMURA, ET AL.
in EMG-RTand its left/right difference for left-handed subjects. These findings were also compatible with our previous work on synchronization error in bilateral simultaneous flexion of elbows (Nakamura, Taniguchi, & Oshima,
1975) . REFERENCES BENTON, A. L,& JOYNT, R. J. Reaction time in unilateral cerebral disease. Confin. N w o l . , 1958, 19, 247-256. DWOND, S. Hemispheric refractoriness and the control of reaction time. Q u d . J . exp. Psychol., 1970, 24, 610-617. D m o m , S. T h e double b ~ a i n . London: Churchill Livingstone, 1972. GBLLHORN, E Proprioception and the motor cortex. Brain, 1949, 72, 35-62. KERR, M., MINGAY,R., & ELITHORN,A. Cerebral dominance in reaction time responses. Bsit. J. Psychol., 1963, 54, 325-336. KLEMMW, E. T. Time uncertainty in simple reaction time. J. exp. Psychol., 1956, 51, 179-184. NAKAMURA, R.,& SAITO, H. Preferred hand and reaction time in different movement patterns. Percept, mot. Shills, 1974, 39, 1275-1281. . NAKAMURA, R., TANIGUCHI,R., & OSHIMA,Y. Synchronization error in bilateral simultaneous flexion of elbows. Percept. mot. Skills, 1975, 40, 527-532. NAKAMURA,R., 8r VIEL, E. The influence of position changes in the proximal joint on EMG-recorded reaction time on key muscles in the human extremity. Pro. ceedings of 7th International Congress of World Confederation for Physical Therapy, Montreal, Canada, 1974. Pp. 119-123. SIMON, J. R. Steadiness, handedness, and hand preference. Percept. mot. Skills, 1964, 18, 203-206. SMITH, L. E., & WHIneY, J. D. Faster reaction time through facilitation of neuromuscular junctional transmission in muscles under maximal stretch. Percept. mot. Skills, 1964, 19, 503-509.
Accepted February 20,1976.
