Perceptual & Motor Skills: Motor Skills & Ergonomics 2015, 120, 2, 519-533. © Perceptual & Motor Skills 2015
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS ON REACTION TIME AND MAXIMUM SPEED OF PERFORMANCE OF UNILATERAL MOVEMENTS1, 2 B. GUTNIK Pirogov Russian National Research Medical University, Moscow, Russian Federation A. SKURVYDAS, A. ZUOZA, I. ZUOZIENE, D. MICKEVIČIENĖ, B. A. ALEKRINSKIS, and K. PUKENAS Lithuanian Sports University, Kaunas, Lithuania D. NASH Unitec, Institute of Technology, Auckland, New Zealand Summary.—The goal was to study reaction time and maximal velocity of upper limbs of healthy young adults of both sexes during transition from a simple to a more involved task. Performance of dominant and non-dominant arms was recorded. Participants were 43 healthy, right-handed, untrained men (n = 22) and women (n = 21), 18–22 years old. The simple task required a single jerk-like movement. The involved task required both speed and accuracy where necessity for high speed of performance was emphasized. The effectiveness of transition between tasks was calculated for both reaction time and maximal velocity. No lateral differences were found. Men usually had a shorter reaction time on both tasks and a higher maximal velocity in the simple task. Women were more effective at modifying velocity.
Researchers have identified several important stages of any sensorymotor reaction: sensation of the stimulus, the decision-making process, and the implementation of motor actions (Botwinick & Thompson, 1966; Kolb & Whishaw, 1995; Schmidt & Lee, 2005; Gold & Shadlen, 2007; Rozenbaum, 2010). The first two stages provide latency and are related to the reaction time, and the third may represent the motor component implementing the movement. In everyday and professional life, people frequently perform multi-goal motor tasks. Many of these tasks require both speed and accuracy. In this case, the sensory information accumulates, and it takes additional time to amass this information (Schouten & Bekker, 1967; Ho, Brown, van Maanen, Forstmann, Wagenmakers, & Serences, 2012). According to Fitts’ Law (1954), movement time is a function of task difficulty. In a more difficult motor task, time of movement is increased and velocity is decreased (Bootsma, Fernandez, & Mottet, 2004). It is well Address correspondence to D. Nash at [email protected]. This article reports on the project, “Advanced approach to the Fitts paradigm, NO TYR-059” performed by the Lithuanian Sports University, Sporto 6, LT 44221 Kaunas, Lithuania.
1 2
DOI 10.2466/25.PMS.120v10x3
12-PMS_Gutnik_150024.indd 519
ISSN 0031-5125
15/04/15 6:33 PM
520
B. GUTNIK, et al.
known that in a speed-accuracy trade-off task the efficiency of this kind of action is limited in terms of accuracy and, probably, in terms of speed in comparison to a simple response (Ho, et al., 2012). The model applied to speed-accuracy trade-off proposed by Meyer, Irwin, Osman, and Kounois (1988) and Meyer, Keith-Smith, Kornblum, Abrams, and Wright (1990) assumes the existence of noise in the neuromotor system that may affect the primary submovement, and the motor noise increases with the velocity of the submovement. To reduce this noise, a participant must reduce the average velocity of movement. It is unclear from the literature how the latency period and velocity of reaction change when a person transitions from the simplest action to a dual perceptual speed-accuracy trade-off task, where both speed and accuracy are emphasized. It was stressed in Wickelgren’s (1977) research that speed-accuracy trade-off experiments are more complicated than experiments measuring reaction time only. The interpretation of these findings is that in a speed-accuracy trade-off task the latency period of reaction should be longer and the average speed should be lower in comparison to any motion without speed-accuracy constraints. It was shown that more complex movements, with greater programming or control requirements, are executed more slowly (Abernethy, Kippers, Hanrahan, Pandy, McManus, & Mackinnon, 2013). If a movement has to be terminated with appreciable accuracy, then the peak velocity decreases (Brown & Cooke, 1990). Reduction of accuracy with increment of speed and vice versa is consistent with data reported by Schmidt (Schmidt & Lee, 2005) and many other researchers. The movement duration eventuated depended on each individual participant’s intrinsic speed-accuracy trade-off for this task, as measured by his probability of hitting the target as a function of movement duration (Dean, Wu, & Maloney, 2007). Researchers have found that when an accuracy constraint was imposed on healthy participants, movement slowness became obvious, and more obvious in patients with Parkinson’s disease (Rand, Stelmach, & Bloedel, 2000). Other researchers have demonstrated that if participants performed right-arm unilateral aiming, the reaction time did not differ significantly in comparison with a task that involved no spatial accuracy constraints (Garry & Franks, 2000). It is well known, however, that different patterns have been established for motor control of the left and right hands. (Babiloni, Carducci, Del Gratta, Demartin, Romani, Babiloni, et al., 2001; Boulinguez, Nougier, & Velay, 2003; Haaland, Prestopnik, Knight, & Lee, 2004). It is also well known that men and women differ in their modulation of spinal (Johnson, Kipp, & Hoffman, 2012) and supraspinal (Field & Whishaw, 2007) motor control and employ different motor control strategies (Shinohara, Li, Kang, Zatsiorsky, & Latash, 2003). There is also a document-
12-PMS_Gutnik_150024.indd 520
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
521
ed lower level of effectiveness of motor performance in women than in men in complex motor tasks (Tan & Tan, 1997; Pedersen, Sigmundsson, Whiting, & Ingvaldsen, 2003; Rodrigues, Vasconcelos, Barreiros, & Barbosa, 2009; Jiménez-Jiménez, Calleja, Alonso-Navarro, Rubio, Navacerrada, Pilo-de-la-Fuente, et al., 2011). No data could be found in the literature to address precise questions regarding the rate of change of the latency period and the maximal speed of performance in transition from a simple motor task to a dual goal-directed action with an associated speed-accuracy constraint. Also, information on the influence of side of action as well as sex in the rate of change of these indices in transition from a simple to a goal-directed task with speed-accuracy motor performance has not been established. It is well known that achievement of maximum velocity defines the end of acceleration if movement continues to be made in a single action, and therefore represents the end of application of an accelerating force (Britton, Thompson, Day, Rothwell, Findley, & Marsden, 1994). The maximal velocity is directly proportional to the value of acceleration applied. Research goal. To characterize the effectiveness of transition from a simple jerk-like motor task to a motor task with spatial accuracy constraints in terms of reaction time and maximal velocity in young healthy adults of both sexes. Method
Participants Participants consisted of 43 healthy, right-handed, untrained men (n = 22) and women (n = 21), 18–22 years old. The degree of right-handedness operated as a selection criterion to the extent that only participants with a laterality of more than +8 on the 10-point Edinburgh inventory (Oldfield, 1971) were selected. Their anthropometric characteristics were mainly of the mesomorphic type. The participants were naive to the purpose of the experiment, and none of them reported any sensory or motor deficits. The research was approved by the local Research Committee of the Lithuanian Sport University (Kaunas). Education regarding the study was provided, and informed consent was obtained from all participants before their entry into the study. Procedure Left and right arms were tested in separate sessions on the same day. The first arm to be tested was alternated across participants. The latest certified model of the Analyzer of Dynamic Parameters of Human Movement™ (patent number 5251, 2005-08-25, Lithuania) was
12-PMS_Gutnik_150024.indd 521
15/04/15 6:33 PM
522
B. GUTNIK, et al.
used for the experiment. The set-up consisted of an armchair in front of a computer monitor on a table. Two vertically oriented joysticks (one for each hand) were placed on the table in front of the monitor. The position of the joysticks and the target were standardized and permanent throughout the experiment. Participants could move the joysticks, but not the target. Only one hand was used at a time. Each participant sat comfortably in the armchair around 0.70 m away from, and in front of, the computer screen that displayed a gray target with a diameter of 6 mm. The trunk of each participant was unable to move forward in the armchair. This arrangement ensured the movement produced was of the upper limb. The target was located at the same height as the eyes of the participant. All three parts of the arm—upper arm, forearm, and wrist—were involved. The distance from the initial point to the target was 16 cm. This distance was limited by the physical possibilities of extension of the elbow. A change of color of the target from gray to red indicated that the participant should be prepared for the start of motion. A color change from red to green was the “Go” signal. The interval prior to the “Go” signal was a constant 1,500 msec., as recommended by Carlsen and Mackinnon (2010). The resistance to motion of the upper extremity was negligible. The time between testing the left and right hands was around 1.5 hours. The recording device was pre-programmed for full testing of just one hand, then it was pre-programmed to test the other hand. It was not practical to re-program the device between series. Two tasks were used for each participant. (a) The simple motor task was a single jerk-like movement of the arm. As soon as possible after the “Go” signal, each participant produced a fast, jerk-like motion toward the target on the screen without any concern for accuracy. The participant could stop in any position producing an under- or overshooting motion. (b) The involved motor task was an interception of a target using a high speed of motion. The necessity for a high speed of performance was initially emphasized. After identification of the “Go” signal, the participant pushed the joystick forward and attempted to intercept the target. Participants were instructed to move the joystick forward as quickly and accurately as possible. Upon initiation of the motion, the participant had no opportunity to correct spatial error in reaching the target. In both motor tasks, the device was adjusted to provide an interval between the signals to perform the motion within each series that ranged from 5 to 10 sec. The interval between series was 30 sec. These periods were important to avoid any type of fatigue. Each participant performed five series of 10 discrete movements, separately with each arm, for each motor task. Thus, the total array of data studied from all participants had 8,600 data points (4,300 for each hand).
12-PMS_Gutnik_150024.indd 522
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
523
The device registered the initial jerk-like motion (simple motor task A) and just the initial phase of movement with associated accuracy constraint (involved motor task B). Thus, the participants used the same ballistic movements. It has to be noted that in these experiments only the first, initial fragment of movement constrained with accuracy was measured. Other fragments of goal-directed movement, which may represent closedloop processes requiring feedback-based adjustment when the participant approaches the target end point, were not recorded by the device.
Analyses of Motion The participants' performances were analyzed individually. Two basic parameters of motor activity were chosen for the study. (a) The latent period of the sensor-motor reaction (reaction time—RT) in msec. Reaction time was the interval between the “Go” signal and the moment the joystick commenced movement, when it achieved 0.1% of maximal velocity. (b) The maximal velocity (VM, mm/sec.) was recorded by the computer with a resolution of ± 1 mm/sec. Individual average reaction time (RT –av. ind) and individual maximal velocity (VM –av. indiv) of a series of 50 movements were determined. Also, group averages (RT –av. group, VM –av. group) with standard deviations were calculated separately for simple and involved motor tasks distinctly for each arm and sex. Two specific indices were also calculated. (1) The effectiveness of transition as demonstrated in modification of reaction time TE(RT) in transition from the simple to the involved task was calculated as a ratio between averaged individual reaction times in the simple and the involved motor task in each individual using the formula: R TE( RT )− ind = T −av.ind−1 RT −av.ind− 2 It was anticipated that the reaction time would increase in transition from the simple motor task to the involved motor task. Thus, the denominator would increase, providing a ratio less than 1. If transition was very effective, this ratio would tend toward 1. (2) The effectiveness of transition as demonstrated in modification of maximal velocity TE(VM) in transition from the simple to the involved motor task was calculated as the ratio between averaged individual maximal velocities in the second (VM –av. indiv-2) and the first tasks (VM –av. indiv-1), using the formula: V TE(VM )− ind = M −av.indiv-2 VM −av.indiv-1 It was also anticipated that the maximal velocity would decrease in transition from the simple to the involved motor task. Thus, the denominator would be larger than the numerator, providing a ratio less than 1. If transition was very effective, this ratio would also tend toward 1.
12-PMS_Gutnik_150024.indd 523
15/04/15 6:33 PM
524
B. GUTNIK, et al.
Final statistical analysis of the results was by Student’s t test for nonuniform distribution using SPSS Version 22. Two-factor dispersion analyses were also performed using this package. The factors were side of performance, sex, and complexity of task. The level of probability denoting a significant difference between data sets was chosen as .05. Results The analysis of movements performed by the left and right arms of the group showed no significant statistical lateral differences in reaction time for either sex in both situations. Large effects were observed during the simple task for the right arm of men versus women and between the left and right arms of men. During the involved task, the reaction times showed a large effect between the left and right arms of men and a small effect between the arms of women. There was also no statistical lateral difference in maximal velocity for either sex. However, a very large effect was noted during the simple task between arms for both men and women. In the involved task all combinations, right versus left and men versus women, showed very large effects (see Tables 1 and 2). When participants performed the more involved task, the reaction time increased and at the same time the maximal speed of movement was noticeably diminished in comparison to the simple motor task. This pattern appeared for both arms and both sexes. There was a significantly shorter reaction time in men than women, especially in the more involved task (Tables 1 and 2). Men usually demonstrated significantly shorter reaction time than women in both situations. Also, the men exceeded the women in maximal speed in the simple motor task. There was no significant difference laterally between arms in terms of effectiveness of transition between tasks for both indices: TE(RT) and TE(Vm). This pattern was demonstrated in both sex groups. A very small effect was noted for men. However, women were much more effective in modifying the value of maximal velocity TE(Vm) in transition from the simple to the involved motor task (Table 3). It was interesting that the values of effectiveness of transition during modification of the maximal speed were much less than the effectiveness of the relative modification of reaction time. This pattern applied to both arms and both sex groups. Discussion The main goal of this work was to characterize the effectiveness of transition during task performance from simple jerk-like movements to more involved actions of upper limbs recording modification of both reaction time and maximal velocity, in young healthy adults of both sexes. Participants were instructed to move the joystick with high speed toward the target; thus, the speed of performance was initially accented in both cases.
12-PMS_Gutnik_150024.indd 524
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
525
TABLE 1 Reaction Time and Maximal Velocity in Simple and Involved Motor Tasks From the Right and Left Arms; Means and Standard Deviations Action Simple
Arm Both arms
Right
Left
p, between sides Cohen’s d
Involved
Both arms
Right
Left
p, between sides Cohen’s d Simple
Both arms
Right
Left
p, between sides Cohen’s d
Involved
Both arms
Right
Left
p, between sides Cohen’s d
Reaction Time (msec.)
M
218
224
212
> .05 1.75
251
254
249
> .05
Men
SD
47
46
48
54
53
55
0.68
M
Women
226
229
224
> .05
0.69 262
264
262
> .05
1,632
1,597
> .05 4.66
505
517
492
> .05
1.97
52
52
52
51
50
53
.05
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS ON REACTION TIME AND MAXIMUM SPEED OF PERFORMANCE OF UNILATERAL MOVEMENTS1, 2 B. GUTNIK Pirogov Russian National Research Medical University, Moscow, Russian Federation A. SKURVYDAS, A. ZUOZA, I. ZUOZIENE, D. MICKEVIČIENĖ, B. A. ALEKRINSKIS, and K. PUKENAS Lithuanian Sports University, Kaunas, Lithuania D. NASH Unitec, Institute of Technology, Auckland, New Zealand Summary.—The goal was to study reaction time and maximal velocity of upper limbs of healthy young adults of both sexes during transition from a simple to a more involved task. Performance of dominant and non-dominant arms was recorded. Participants were 43 healthy, right-handed, untrained men (n = 22) and women (n = 21), 18–22 years old. The simple task required a single jerk-like movement. The involved task required both speed and accuracy where necessity for high speed of performance was emphasized. The effectiveness of transition between tasks was calculated for both reaction time and maximal velocity. No lateral differences were found. Men usually had a shorter reaction time on both tasks and a higher maximal velocity in the simple task. Women were more effective at modifying velocity.
Researchers have identified several important stages of any sensorymotor reaction: sensation of the stimulus, the decision-making process, and the implementation of motor actions (Botwinick & Thompson, 1966; Kolb & Whishaw, 1995; Schmidt & Lee, 2005; Gold & Shadlen, 2007; Rozenbaum, 2010). The first two stages provide latency and are related to the reaction time, and the third may represent the motor component implementing the movement. In everyday and professional life, people frequently perform multi-goal motor tasks. Many of these tasks require both speed and accuracy. In this case, the sensory information accumulates, and it takes additional time to amass this information (Schouten & Bekker, 1967; Ho, Brown, van Maanen, Forstmann, Wagenmakers, & Serences, 2012). According to Fitts’ Law (1954), movement time is a function of task difficulty. In a more difficult motor task, time of movement is increased and velocity is decreased (Bootsma, Fernandez, & Mottet, 2004). It is well Address correspondence to D. Nash at [email protected]. This article reports on the project, “Advanced approach to the Fitts paradigm, NO TYR-059” performed by the Lithuanian Sports University, Sporto 6, LT 44221 Kaunas, Lithuania.
1 2
DOI 10.2466/25.PMS.120v10x3
12-PMS_Gutnik_150024.indd 519
ISSN 0031-5125
15/04/15 6:33 PM
520
B. GUTNIK, et al.
known that in a speed-accuracy trade-off task the efficiency of this kind of action is limited in terms of accuracy and, probably, in terms of speed in comparison to a simple response (Ho, et al., 2012). The model applied to speed-accuracy trade-off proposed by Meyer, Irwin, Osman, and Kounois (1988) and Meyer, Keith-Smith, Kornblum, Abrams, and Wright (1990) assumes the existence of noise in the neuromotor system that may affect the primary submovement, and the motor noise increases with the velocity of the submovement. To reduce this noise, a participant must reduce the average velocity of movement. It is unclear from the literature how the latency period and velocity of reaction change when a person transitions from the simplest action to a dual perceptual speed-accuracy trade-off task, where both speed and accuracy are emphasized. It was stressed in Wickelgren’s (1977) research that speed-accuracy trade-off experiments are more complicated than experiments measuring reaction time only. The interpretation of these findings is that in a speed-accuracy trade-off task the latency period of reaction should be longer and the average speed should be lower in comparison to any motion without speed-accuracy constraints. It was shown that more complex movements, with greater programming or control requirements, are executed more slowly (Abernethy, Kippers, Hanrahan, Pandy, McManus, & Mackinnon, 2013). If a movement has to be terminated with appreciable accuracy, then the peak velocity decreases (Brown & Cooke, 1990). Reduction of accuracy with increment of speed and vice versa is consistent with data reported by Schmidt (Schmidt & Lee, 2005) and many other researchers. The movement duration eventuated depended on each individual participant’s intrinsic speed-accuracy trade-off for this task, as measured by his probability of hitting the target as a function of movement duration (Dean, Wu, & Maloney, 2007). Researchers have found that when an accuracy constraint was imposed on healthy participants, movement slowness became obvious, and more obvious in patients with Parkinson’s disease (Rand, Stelmach, & Bloedel, 2000). Other researchers have demonstrated that if participants performed right-arm unilateral aiming, the reaction time did not differ significantly in comparison with a task that involved no spatial accuracy constraints (Garry & Franks, 2000). It is well known, however, that different patterns have been established for motor control of the left and right hands. (Babiloni, Carducci, Del Gratta, Demartin, Romani, Babiloni, et al., 2001; Boulinguez, Nougier, & Velay, 2003; Haaland, Prestopnik, Knight, & Lee, 2004). It is also well known that men and women differ in their modulation of spinal (Johnson, Kipp, & Hoffman, 2012) and supraspinal (Field & Whishaw, 2007) motor control and employ different motor control strategies (Shinohara, Li, Kang, Zatsiorsky, & Latash, 2003). There is also a document-
12-PMS_Gutnik_150024.indd 520
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
521
ed lower level of effectiveness of motor performance in women than in men in complex motor tasks (Tan & Tan, 1997; Pedersen, Sigmundsson, Whiting, & Ingvaldsen, 2003; Rodrigues, Vasconcelos, Barreiros, & Barbosa, 2009; Jiménez-Jiménez, Calleja, Alonso-Navarro, Rubio, Navacerrada, Pilo-de-la-Fuente, et al., 2011). No data could be found in the literature to address precise questions regarding the rate of change of the latency period and the maximal speed of performance in transition from a simple motor task to a dual goal-directed action with an associated speed-accuracy constraint. Also, information on the influence of side of action as well as sex in the rate of change of these indices in transition from a simple to a goal-directed task with speed-accuracy motor performance has not been established. It is well known that achievement of maximum velocity defines the end of acceleration if movement continues to be made in a single action, and therefore represents the end of application of an accelerating force (Britton, Thompson, Day, Rothwell, Findley, & Marsden, 1994). The maximal velocity is directly proportional to the value of acceleration applied. Research goal. To characterize the effectiveness of transition from a simple jerk-like motor task to a motor task with spatial accuracy constraints in terms of reaction time and maximal velocity in young healthy adults of both sexes. Method
Participants Participants consisted of 43 healthy, right-handed, untrained men (n = 22) and women (n = 21), 18–22 years old. The degree of right-handedness operated as a selection criterion to the extent that only participants with a laterality of more than +8 on the 10-point Edinburgh inventory (Oldfield, 1971) were selected. Their anthropometric characteristics were mainly of the mesomorphic type. The participants were naive to the purpose of the experiment, and none of them reported any sensory or motor deficits. The research was approved by the local Research Committee of the Lithuanian Sport University (Kaunas). Education regarding the study was provided, and informed consent was obtained from all participants before their entry into the study. Procedure Left and right arms were tested in separate sessions on the same day. The first arm to be tested was alternated across participants. The latest certified model of the Analyzer of Dynamic Parameters of Human Movement™ (patent number 5251, 2005-08-25, Lithuania) was
12-PMS_Gutnik_150024.indd 521
15/04/15 6:33 PM
522
B. GUTNIK, et al.
used for the experiment. The set-up consisted of an armchair in front of a computer monitor on a table. Two vertically oriented joysticks (one for each hand) were placed on the table in front of the monitor. The position of the joysticks and the target were standardized and permanent throughout the experiment. Participants could move the joysticks, but not the target. Only one hand was used at a time. Each participant sat comfortably in the armchair around 0.70 m away from, and in front of, the computer screen that displayed a gray target with a diameter of 6 mm. The trunk of each participant was unable to move forward in the armchair. This arrangement ensured the movement produced was of the upper limb. The target was located at the same height as the eyes of the participant. All three parts of the arm—upper arm, forearm, and wrist—were involved. The distance from the initial point to the target was 16 cm. This distance was limited by the physical possibilities of extension of the elbow. A change of color of the target from gray to red indicated that the participant should be prepared for the start of motion. A color change from red to green was the “Go” signal. The interval prior to the “Go” signal was a constant 1,500 msec., as recommended by Carlsen and Mackinnon (2010). The resistance to motion of the upper extremity was negligible. The time between testing the left and right hands was around 1.5 hours. The recording device was pre-programmed for full testing of just one hand, then it was pre-programmed to test the other hand. It was not practical to re-program the device between series. Two tasks were used for each participant. (a) The simple motor task was a single jerk-like movement of the arm. As soon as possible after the “Go” signal, each participant produced a fast, jerk-like motion toward the target on the screen without any concern for accuracy. The participant could stop in any position producing an under- or overshooting motion. (b) The involved motor task was an interception of a target using a high speed of motion. The necessity for a high speed of performance was initially emphasized. After identification of the “Go” signal, the participant pushed the joystick forward and attempted to intercept the target. Participants were instructed to move the joystick forward as quickly and accurately as possible. Upon initiation of the motion, the participant had no opportunity to correct spatial error in reaching the target. In both motor tasks, the device was adjusted to provide an interval between the signals to perform the motion within each series that ranged from 5 to 10 sec. The interval between series was 30 sec. These periods were important to avoid any type of fatigue. Each participant performed five series of 10 discrete movements, separately with each arm, for each motor task. Thus, the total array of data studied from all participants had 8,600 data points (4,300 for each hand).
12-PMS_Gutnik_150024.indd 522
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
523
The device registered the initial jerk-like motion (simple motor task A) and just the initial phase of movement with associated accuracy constraint (involved motor task B). Thus, the participants used the same ballistic movements. It has to be noted that in these experiments only the first, initial fragment of movement constrained with accuracy was measured. Other fragments of goal-directed movement, which may represent closedloop processes requiring feedback-based adjustment when the participant approaches the target end point, were not recorded by the device.
Analyses of Motion The participants' performances were analyzed individually. Two basic parameters of motor activity were chosen for the study. (a) The latent period of the sensor-motor reaction (reaction time—RT) in msec. Reaction time was the interval between the “Go” signal and the moment the joystick commenced movement, when it achieved 0.1% of maximal velocity. (b) The maximal velocity (VM, mm/sec.) was recorded by the computer with a resolution of ± 1 mm/sec. Individual average reaction time (RT –av. ind) and individual maximal velocity (VM –av. indiv) of a series of 50 movements were determined. Also, group averages (RT –av. group, VM –av. group) with standard deviations were calculated separately for simple and involved motor tasks distinctly for each arm and sex. Two specific indices were also calculated. (1) The effectiveness of transition as demonstrated in modification of reaction time TE(RT) in transition from the simple to the involved task was calculated as a ratio between averaged individual reaction times in the simple and the involved motor task in each individual using the formula: R TE( RT )− ind = T −av.ind−1 RT −av.ind− 2 It was anticipated that the reaction time would increase in transition from the simple motor task to the involved motor task. Thus, the denominator would increase, providing a ratio less than 1. If transition was very effective, this ratio would tend toward 1. (2) The effectiveness of transition as demonstrated in modification of maximal velocity TE(VM) in transition from the simple to the involved motor task was calculated as the ratio between averaged individual maximal velocities in the second (VM –av. indiv-2) and the first tasks (VM –av. indiv-1), using the formula: V TE(VM )− ind = M −av.indiv-2 VM −av.indiv-1 It was also anticipated that the maximal velocity would decrease in transition from the simple to the involved motor task. Thus, the denominator would be larger than the numerator, providing a ratio less than 1. If transition was very effective, this ratio would also tend toward 1.
12-PMS_Gutnik_150024.indd 523
15/04/15 6:33 PM
524
B. GUTNIK, et al.
Final statistical analysis of the results was by Student’s t test for nonuniform distribution using SPSS Version 22. Two-factor dispersion analyses were also performed using this package. The factors were side of performance, sex, and complexity of task. The level of probability denoting a significant difference between data sets was chosen as .05. Results The analysis of movements performed by the left and right arms of the group showed no significant statistical lateral differences in reaction time for either sex in both situations. Large effects were observed during the simple task for the right arm of men versus women and between the left and right arms of men. During the involved task, the reaction times showed a large effect between the left and right arms of men and a small effect between the arms of women. There was also no statistical lateral difference in maximal velocity for either sex. However, a very large effect was noted during the simple task between arms for both men and women. In the involved task all combinations, right versus left and men versus women, showed very large effects (see Tables 1 and 2). When participants performed the more involved task, the reaction time increased and at the same time the maximal speed of movement was noticeably diminished in comparison to the simple motor task. This pattern appeared for both arms and both sexes. There was a significantly shorter reaction time in men than women, especially in the more involved task (Tables 1 and 2). Men usually demonstrated significantly shorter reaction time than women in both situations. Also, the men exceeded the women in maximal speed in the simple motor task. There was no significant difference laterally between arms in terms of effectiveness of transition between tasks for both indices: TE(RT) and TE(Vm). This pattern was demonstrated in both sex groups. A very small effect was noted for men. However, women were much more effective in modifying the value of maximal velocity TE(Vm) in transition from the simple to the involved motor task (Table 3). It was interesting that the values of effectiveness of transition during modification of the maximal speed were much less than the effectiveness of the relative modification of reaction time. This pattern applied to both arms and both sex groups. Discussion The main goal of this work was to characterize the effectiveness of transition during task performance from simple jerk-like movements to more involved actions of upper limbs recording modification of both reaction time and maximal velocity, in young healthy adults of both sexes. Participants were instructed to move the joystick with high speed toward the target; thus, the speed of performance was initially accented in both cases.
12-PMS_Gutnik_150024.indd 524
15/04/15 6:33 PM
INFLUENCE OF SPATIAL ACCURACY CONSTRAINTS
525
TABLE 1 Reaction Time and Maximal Velocity in Simple and Involved Motor Tasks From the Right and Left Arms; Means and Standard Deviations Action Simple
Arm Both arms
Right
Left
p, between sides Cohen’s d
Involved
Both arms
Right
Left
p, between sides Cohen’s d Simple
Both arms
Right
Left
p, between sides Cohen’s d
Involved
Both arms
Right
Left
p, between sides Cohen’s d
Reaction Time (msec.)
M
218
224
212
> .05 1.75
251
254
249
> .05
Men
SD
47
46
48
54
53
55
0.68
M
Women
226
229
224
> .05
0.69 262
264
262
> .05
1,632
1,597
> .05 4.66
505
517
492
> .05
1.97
52
52
52
51
50
53
.05
