Perceptual and Motor Skills, 1977,411,709-710. @ Perceptual and Motor Skills 1977
REACTION TIME IN SIMULTANEOUS MOTIONS R. TANIGUCHI, R. NAKAMURA, AND Y. OSHIMA Tokyo Met~opolitanInsthr~tefor Neurosciences Depa~hnentof Rehabilitation Summary.-EMG-RTs of biceps and triceps brachii muscles were measured in 3 different tasks: isolated motions, flexion or extension of either forearm; bilateral symmetrical motions, flexion or extension of both forearms; bilateral opposite motions, flexion of a forearm and extension of the other. EMG-RTs of opposite motions were slower than those of isolated and symmetrical motions, EMGRTs of symmetrical motions were nearly equivalent to those of isolated motions. Simplicity and complexity of simultaneous motions are discussed. It is generally believed as a principle of motion economy that motions of arms should be made in opposite and symmetrical directions and simultaneously. The symmetrical movements of arms tend to balance each other, reducing the shock and jar on the body and enabling the worker to perform his task with less mental and physical effort ( 2 ) . In this paper we studied how simple reaction time in simultaneous motions is influenced by symmetric and/or opposite direction of motions. The experiments were performed on 9 normal right-handed subjects, 5 male and 4 female, aged from 23 to 45 yr. ( M 33.4 2 6.3). They were knowledgeable subjects. In a quiet room the subject with closed eyes was seated on a chair with comfortable posture. Both forearms were kept at elbow angle 100" (full extension = 180") and shoulders at neutral position by the forearm supports ( 7 ) . The stimulus was a peep sound (1000 Hz, 50-msec. duration, about 100 d b ) which was presented 2 to 4 sec. after a warning signal. The reaction time was measured with the elearomyographic reaction time (EMG-RT) of biceps and triceps brachii muscles of both arms by the previously reported method ( 5 ) . Motions of response were as follows: Task 1, isolated motionsflexion or extension of either forearm; Task 2, bilateral symmetrical motions-flexion or extension of both forearms; Task 3, bilateral opposite motions-flexion of a forearm and extension of the other, in all 8 tasks. The coupling of prime mover muscles was homonymous in Task 2 and non-homonymous in Task 3. In a training session the subject was given several trials on each task, after which EMG-RTs were measured. The number of trials was 10 for each cask and the interval of trials was about 15 sec. The seauence of tasks was randomly changed in each trial and subject. Table 1 shows over-all means and standard errors of EMG-RTs in all subjects. Variances of EMG-RTs were homogeneous among the motions and subjects (Cochran's method, G = 0.027, w/k = 9 / 1 0 8 ) . Therefore the data were analyzed with four-way analysis of variance, arm x prime mover x task X subject, as shown in Table 2. Main effects of arm and prime mover were not significant, nor was their interaction. The EMG-RTs did not differ among arms and/or prime mover muscles, although different results are TABLE 1 MEANTIMES(SE) OF EMG-RTs (MSEC.) Arm Left
biceps triceps Right biceps trice~s
Isolated 97.0 97.6 99.0 94.5
(10.0) (11.1) ( 6.9) (10.2)
Symmetrial
Opposite
97.8 ( 9.4) 100.5 ( 9.9) 98.8 ( 9.4) 99.1 (10.7)
109.1 (10.3) 113.4 (11.9) 110.9 ( 9.6) 110.2 (11.5)
R. TANIGUCHI, ET AL. TABLE 2 ANALYSISOF VARIANCE,ARM X PRIMEMOVER X TASK X SUBJECT Source Arm ( A ) Prime mover ( P ) A X P Task (T) A x T P x T A X P X T Subject A X S P X S
T X S A X P X S A x T x S P x T x S A x P x T x S Error Tocal
df 1 1 1
2 2
2 2 8 8 8 16 8 16 16 16 97 2 1079
MS
P
70.53 60.68 1169.79 20235.78 6.34 396.29 55.22 12173.22 117.56 154.24 128.73 508.50 45.02 137.98 157.91 94.03
0.60 0.39 2.30 157.20 0.14 2.87 0.35 129.46
P
REACTION TIME IN SIMULTANEOUS MOTIONS R. TANIGUCHI, R. NAKAMURA, AND Y. OSHIMA Tokyo Met~opolitanInsthr~tefor Neurosciences Depa~hnentof Rehabilitation Summary.-EMG-RTs of biceps and triceps brachii muscles were measured in 3 different tasks: isolated motions, flexion or extension of either forearm; bilateral symmetrical motions, flexion or extension of both forearms; bilateral opposite motions, flexion of a forearm and extension of the other. EMG-RTs of opposite motions were slower than those of isolated and symmetrical motions, EMGRTs of symmetrical motions were nearly equivalent to those of isolated motions. Simplicity and complexity of simultaneous motions are discussed. It is generally believed as a principle of motion economy that motions of arms should be made in opposite and symmetrical directions and simultaneously. The symmetrical movements of arms tend to balance each other, reducing the shock and jar on the body and enabling the worker to perform his task with less mental and physical effort ( 2 ) . In this paper we studied how simple reaction time in simultaneous motions is influenced by symmetric and/or opposite direction of motions. The experiments were performed on 9 normal right-handed subjects, 5 male and 4 female, aged from 23 to 45 yr. ( M 33.4 2 6.3). They were knowledgeable subjects. In a quiet room the subject with closed eyes was seated on a chair with comfortable posture. Both forearms were kept at elbow angle 100" (full extension = 180") and shoulders at neutral position by the forearm supports ( 7 ) . The stimulus was a peep sound (1000 Hz, 50-msec. duration, about 100 d b ) which was presented 2 to 4 sec. after a warning signal. The reaction time was measured with the elearomyographic reaction time (EMG-RT) of biceps and triceps brachii muscles of both arms by the previously reported method ( 5 ) . Motions of response were as follows: Task 1, isolated motionsflexion or extension of either forearm; Task 2, bilateral symmetrical motions-flexion or extension of both forearms; Task 3, bilateral opposite motions-flexion of a forearm and extension of the other, in all 8 tasks. The coupling of prime mover muscles was homonymous in Task 2 and non-homonymous in Task 3. In a training session the subject was given several trials on each task, after which EMG-RTs were measured. The number of trials was 10 for each cask and the interval of trials was about 15 sec. The seauence of tasks was randomly changed in each trial and subject. Table 1 shows over-all means and standard errors of EMG-RTs in all subjects. Variances of EMG-RTs were homogeneous among the motions and subjects (Cochran's method, G = 0.027, w/k = 9 / 1 0 8 ) . Therefore the data were analyzed with four-way analysis of variance, arm x prime mover x task X subject, as shown in Table 2. Main effects of arm and prime mover were not significant, nor was their interaction. The EMG-RTs did not differ among arms and/or prime mover muscles, although different results are TABLE 1 MEANTIMES(SE) OF EMG-RTs (MSEC.) Arm Left
biceps triceps Right biceps trice~s
Isolated 97.0 97.6 99.0 94.5
(10.0) (11.1) ( 6.9) (10.2)
Symmetrial
Opposite
97.8 ( 9.4) 100.5 ( 9.9) 98.8 ( 9.4) 99.1 (10.7)
109.1 (10.3) 113.4 (11.9) 110.9 ( 9.6) 110.2 (11.5)
R. TANIGUCHI, ET AL. TABLE 2 ANALYSISOF VARIANCE,ARM X PRIMEMOVER X TASK X SUBJECT Source Arm ( A ) Prime mover ( P ) A X P Task (T) A x T P x T A X P X T Subject A X S P X S
T X S A X P X S A x T x S P x T x S A x P x T x S Error Tocal
df 1 1 1
2 2
2 2 8 8 8 16 8 16 16 16 97 2 1079
MS
P
70.53 60.68 1169.79 20235.78 6.34 396.29 55.22 12173.22 117.56 154.24 128.73 508.50 45.02 137.98 157.91 94.03
0.60 0.39 2.30 157.20 0.14 2.87 0.35 129.46
P
