Perceptual and Motor Skilk, 1991, 73, 255-264.
O Perceptual and Motor Skills 1991
VALIDATION O F TWO DEVICES FOR EVALUATION O F HUMAN PSYCHOMOTOR PERFORMANCE ' G. W. KUNSMAN, J. E . MANNO, M. A. PRZEKOPAND B. R. MANNO Louisiana Staate University Medical Center-Shreveport Summary.-The Pursuit Meter I11 (PM 111) and the Simultaneous Hand and Foot Tracking (SHAFT) task are microcomputer-based devices for the evaluation of human psychomotor performance. Both devices are pursuit-tracking tasks. The primary task (PM 111) requires a subject superimpose a line over a computer-generated sine wave. The computer wave is black and the subject's wave is red. The vertical position of the subject's wave is determined by a joystick controller. The SHAFTadds a second simultaneous tracking task (FTT) that is operated by means of a foot control. Ten naive subjects performed either device for 5 sessions/day over a t h e - d a y period. Each session consisted of 5 sweeps of the sine wave pattern. Mean performance on both tasks generally improved over the assessment period, and differential stability was reached within 10 sweeps for each device.
The evaluation of psychomotor performance is a daily occurrence for most people. Whether the ability to perform routine yet complex psychomotor tasks is assessed on the highway or in the workplace, such monitoring frequently occurs. Inability to perform may have economic and legal implications as well as affect the safety of other persons. Many factors exist which may affect an individual's ability to perform routine tasks such as operating machinery or automobile driving, but psychoactive drugs (including alcohol) are frequently implicated (Garriott & Latman, 1976; Johnson & White, 1989; Koelega, 1989; Moskowitz, 1984; Seppala, Linnoila, & Mattila, 1979). Workplace and driving performance may be considered to be a series of tasks requiring vigilance and divided attention (Koelega, 1989). To evaluate the effects of environmental conditions (e.g., illness, disease, exposure to toxicants in the workplace, etc.) and drugs on driving and workplace safety and efficiency a large number of psychomotor tests have been developed (Hindmarch, 1980). Since laboratory experiments provide a controlled environment, human performance testing most frequently occurs in this setting. Broadbent (1984) stated that the effects of a drug on performance cannot be predicted from a single test and that the performance of interest must be exactly simulated or a battery of tests should be used. Laboratory tests seldom exactly simulate a type of performance and the generalization of the results from these tests to a particular task (e.g., driving) is somewhat speculative (Clayton, 1976). The results of laboratory tests may be applied to Address correspondence to J. E. Manno, Ph.D., Department of Pharmacolo y, Section of ~oxicology, Louisiana State University Medical Center, P O Box 33931, ~kreveport, LA 71130-3932.
256
G. W. KUNSMAN, ET AL.
suggest ways in which drugs or other conditions impair performance (Clayton, 1976) and batteries should be developed to model aspects of a number of different types of tasks routinely engaged in during driving or job performance. Pursuit tracking has been used to evaluate psychomotor performance since the development of the pursuit rotor (Koerth, 1922). This task and a number of variants have been used alone and in combination with other tasks for the evaluation of performance (Ammons, 1955; Hughes, Forney, & Richards, 1965; Manno, Kipplinger, Haine, Bennett, & Forney, 1970; Podton, 1969). The tasks described here are a pursuit tracking task (PM 111), which is a modification of the Pursuit Meter I1 described by Ferslew, Manno, Manno, Vekovius, Hubbard, and Bairnsfather (1982), and a divided attention task (SHAFT), which combines two tracking tasks, the PM 111 and a foot-tracking task (FTT). The purpose of this study was to evaluate the effects of practice and learning on the devices and assess the number of practice trials required to achieve differential stability for each task.
Subjects
Subjects were 20 healthy volunteers between 18 and 54 years of age. Fifteen men and 5 women were tested, using 10 subjects on each device. Subjects were paid for their participation and informed written consent was obtained prior to testing. The protocol was approved by the University Institutional Review Board. Subjects ranged from proficient videogame players (subjects' self-ratings) to no videogame or computer experience. All subjects were asked to avoid consuming any alcoholic beverages or other drugs on the night before testing or on the day of testing. Subjects' compliance was evaluated by testing a urine sample for the presence of cannabinoids (marijuana), benzoyl ecgonine (cocaine metabolite), propoxyphene, phencyclidine (PCP), opiates, amphetamines, barbiturates, methaqualone, benzodiazepines, and ethanol. No drug use was detected among the 20 subjects.
Equipment The Pursuit Meter I11 and the SHAFT are composed of a number of elements. A Tandy Color Computer 3 (No. 26-3334, Tandy Corp., Fort Worth, TX) with ROM resident Color Computer 3 Extended Basic@ and 128K RAM was used to generate the test patterns on a CM-8 high resolution RGB analog monitor (No. 26-3215, Tandy Corp., Fort Worth, TX). Programs written in Color Computer 3 Extended Basic@ were stored on a 5 % -in. floppy disk and loaded using an FD502 Disk Drive (No. 26-3133, Tandy Corp., Fort Worth, TX). Results were printed on a Microline 82A dot matrix
VALIDITYOF PSYCHOMOTOR DEVICES
257
printer (Okidata Corp., Mount Laurel, NJ). Each subject's input was from a Deluxe Joystick (No. 26-3012B, Tandy Corp., Fort Worth, TX) for the PM I11 and from the joystick and a foot pedal (No. 50-8020-00, Happ Controls, Elk Grove, IL) for the SHAFT. The stock potentiometer was removed from the foot controller and replaced with a 50 kQ linear potentiometer (No. 53CS, RV4NAYSD 503A, Clarostat Manufacturing Co., Inc., Dover, NH). The foot controller was connected to the computer through the left joystick port by means of a 5-pin DIN connector using pins 1 (comparator input, right-left), 3 (GND), and 5 ( + 5 VDC).
Test Descriptions Pursuit Meter III.-The
device described here is a programming and hardware modification of the Pursuit Meter I1 (Ferslew, et al., 1982). The computer generates a black sine wave on the monitor screen from left to right. Although the number of possible wave fronts that can be generated is large, only a simple sine wave pattern is used in this device because it has a high degree of predictabhty which facilitates the subject's performance (Ferslew, Manno, Manno, Hubbard, & Vekovius, 1783). Subjects are required to track the sine wave using the joystick controller. The subject's wave is in red and the joystick controls the vertical position of the subject's wavefront. The vertical position of that wave is directly related to the movement of the joystick. The speed of horizontal movement and horizontal position are controlled by the computer program. The computer compares the position of the subject's sine wave to the reference sine wave once in every vertical column. The absolute value of the difference in positions is summed over the entire sweep (320 vertical columns) and constitutes the error score for that trial. the task so lower scores The score reflects the subject's inability to indicate better performance. Presentation of 1 sweep (1 complete sine wave pattern across the width of the monitor) is 70 sec. in duration (0.1 cycleslsec.). Each subject's results are printed to the hard copy device after every sweep and the mean of the five sweeps is printed at the culmination of that session. The pursuit-tracking task requires the integration of a number of cognitive and psychomotor tasks such as reaction time, visual perception, and fine motor coordination and is believed to measure attentive motor performance (Hughes & Forney, 1964). Simultaneous Hand and Foot Eackzng task.-A divided-attention task involves the simultaneous performance of two or more subtasks. The SHAFT described here is the combination of two tracking tasks (Fig. 1).The primary task is the PM I11 described above. The secondary task is a simple tracking task that uses a foot control for the subject's input. The foot-tracking task (FTT) requires the subject to maintain the position of a horizontal bar presented below the PM I11 sine wave on the computer monitor within a given range. That range is defined by two vertical lines within a larger response
G. W.KUNSMAN, ETAL. T
nJ
Joystick
rY
Controller
Indicator line is blue when in range
d
Foot
I
rP
Joystick
Controller
lndicator line is red when out of range
FIG.1.
Divided attention task
area also bound by two vertical lines. The target range moves within the larger area four tirnes/sweep according to a predetermined pattern. That pattern changes with each sweep within a session but does not vary between sessions. The FTT, despite being considered a secondary task, is scored to
VALIDITY OF PSYCHOMOTOR DEVICES
259
assure each subject's compliance with both aspects of the test. The score is reflective of the time spent out-of-range, with a maximum score of 321. The subject's indicator is a red line when out-of-range which changes to a blue line when the leading edge of the line is within the defined range. The position of the indicator is sampled each time the computer plots a point of the sine wave and, if the indicator is not within the range, the error score is increased by 1. The degree or extent out-of-range is not considered in this score, but it is simply a measure of on-target or off-target. Error scores are printed separately for each subtask and, as in the PM 111, a set of five complete sweeps of the sine wave constitutes a single session. The combination of the two traclung tasks places the subject in a situation in which the capacity to absorb and respond to all relevant information is assessed. Moskowitz (1984) suggests that placing subjects in a situation requiring sequential timesharing of attention between two or more information sources is a necessary test in the evaluation of behavioral drug impairment because divided attention tasks are frequently highly sensitive to drug effects.
Procedure Each task was evaluated in a separate study. The procedure for each study was identical. Ten subjects were tested on each task. Three of the female subjects were tested on the SHAFT and the other two were tested on the PM 111. Subjects were required to be naive to the task on which they were tested. After obtaining signed informed consent, the subject was given a visual demonstration of the task in operation while the purpose and scoring of the test was explained. Subjects were not allowed practice trials before the study began. Each subject tested for a total of 15 sessions (75 total sweeps) over a 3-day period. Each testing period was approximately 1 hr. in duration and the testing periods occurred on three nonconsecutive days over a 2- or 3-week period. Subjects were tested at the same time of day for each testingperiod. Each sweep was 70 sec. in duration and one session required approximately 6 min. Subjects were given a 5-min. rest between sessions on each testing day. Pursuit Meter III Analysis of the pursuit meter data is based on the mean score for each of the 15 sessions (5 sweeps/session). The mean error score for the 10 subjects in this phase of the study is plotted in Fig. 2 and tabulated in Table 1. The plot of means depicts a learning curve that does not reach an asymptote. Performance improved rapidly over the first few sessions and shows a continued gradual improvement over the period of the study. A two-way (session by subject) analysis of variance was performed on = 38.55, the 15 sessions. The main effect of session was significant (F,,,,,,
260
G. W. K U N S M A N , ETAL.
p < .001), but the main effect of subject was not s ~ ~ n i f i c a n(F,,,,, t = 1.17, p = .38). A significant interaction of subject x session was also observed (F,,6,600 = 2.51, p
O Perceptual and Motor Skills 1991
VALIDATION O F TWO DEVICES FOR EVALUATION O F HUMAN PSYCHOMOTOR PERFORMANCE ' G. W. KUNSMAN, J. E . MANNO, M. A. PRZEKOPAND B. R. MANNO Louisiana Staate University Medical Center-Shreveport Summary.-The Pursuit Meter I11 (PM 111) and the Simultaneous Hand and Foot Tracking (SHAFT) task are microcomputer-based devices for the evaluation of human psychomotor performance. Both devices are pursuit-tracking tasks. The primary task (PM 111) requires a subject superimpose a line over a computer-generated sine wave. The computer wave is black and the subject's wave is red. The vertical position of the subject's wave is determined by a joystick controller. The SHAFTadds a second simultaneous tracking task (FTT) that is operated by means of a foot control. Ten naive subjects performed either device for 5 sessions/day over a t h e - d a y period. Each session consisted of 5 sweeps of the sine wave pattern. Mean performance on both tasks generally improved over the assessment period, and differential stability was reached within 10 sweeps for each device.
The evaluation of psychomotor performance is a daily occurrence for most people. Whether the ability to perform routine yet complex psychomotor tasks is assessed on the highway or in the workplace, such monitoring frequently occurs. Inability to perform may have economic and legal implications as well as affect the safety of other persons. Many factors exist which may affect an individual's ability to perform routine tasks such as operating machinery or automobile driving, but psychoactive drugs (including alcohol) are frequently implicated (Garriott & Latman, 1976; Johnson & White, 1989; Koelega, 1989; Moskowitz, 1984; Seppala, Linnoila, & Mattila, 1979). Workplace and driving performance may be considered to be a series of tasks requiring vigilance and divided attention (Koelega, 1989). To evaluate the effects of environmental conditions (e.g., illness, disease, exposure to toxicants in the workplace, etc.) and drugs on driving and workplace safety and efficiency a large number of psychomotor tests have been developed (Hindmarch, 1980). Since laboratory experiments provide a controlled environment, human performance testing most frequently occurs in this setting. Broadbent (1984) stated that the effects of a drug on performance cannot be predicted from a single test and that the performance of interest must be exactly simulated or a battery of tests should be used. Laboratory tests seldom exactly simulate a type of performance and the generalization of the results from these tests to a particular task (e.g., driving) is somewhat speculative (Clayton, 1976). The results of laboratory tests may be applied to Address correspondence to J. E. Manno, Ph.D., Department of Pharmacolo y, Section of ~oxicology, Louisiana State University Medical Center, P O Box 33931, ~kreveport, LA 71130-3932.
256
G. W. KUNSMAN, ET AL.
suggest ways in which drugs or other conditions impair performance (Clayton, 1976) and batteries should be developed to model aspects of a number of different types of tasks routinely engaged in during driving or job performance. Pursuit tracking has been used to evaluate psychomotor performance since the development of the pursuit rotor (Koerth, 1922). This task and a number of variants have been used alone and in combination with other tasks for the evaluation of performance (Ammons, 1955; Hughes, Forney, & Richards, 1965; Manno, Kipplinger, Haine, Bennett, & Forney, 1970; Podton, 1969). The tasks described here are a pursuit tracking task (PM 111), which is a modification of the Pursuit Meter I1 described by Ferslew, Manno, Manno, Vekovius, Hubbard, and Bairnsfather (1982), and a divided attention task (SHAFT), which combines two tracking tasks, the PM 111 and a foot-tracking task (FTT). The purpose of this study was to evaluate the effects of practice and learning on the devices and assess the number of practice trials required to achieve differential stability for each task.
Subjects
Subjects were 20 healthy volunteers between 18 and 54 years of age. Fifteen men and 5 women were tested, using 10 subjects on each device. Subjects were paid for their participation and informed written consent was obtained prior to testing. The protocol was approved by the University Institutional Review Board. Subjects ranged from proficient videogame players (subjects' self-ratings) to no videogame or computer experience. All subjects were asked to avoid consuming any alcoholic beverages or other drugs on the night before testing or on the day of testing. Subjects' compliance was evaluated by testing a urine sample for the presence of cannabinoids (marijuana), benzoyl ecgonine (cocaine metabolite), propoxyphene, phencyclidine (PCP), opiates, amphetamines, barbiturates, methaqualone, benzodiazepines, and ethanol. No drug use was detected among the 20 subjects.
Equipment The Pursuit Meter I11 and the SHAFT are composed of a number of elements. A Tandy Color Computer 3 (No. 26-3334, Tandy Corp., Fort Worth, TX) with ROM resident Color Computer 3 Extended Basic@ and 128K RAM was used to generate the test patterns on a CM-8 high resolution RGB analog monitor (No. 26-3215, Tandy Corp., Fort Worth, TX). Programs written in Color Computer 3 Extended Basic@ were stored on a 5 % -in. floppy disk and loaded using an FD502 Disk Drive (No. 26-3133, Tandy Corp., Fort Worth, TX). Results were printed on a Microline 82A dot matrix
VALIDITYOF PSYCHOMOTOR DEVICES
257
printer (Okidata Corp., Mount Laurel, NJ). Each subject's input was from a Deluxe Joystick (No. 26-3012B, Tandy Corp., Fort Worth, TX) for the PM I11 and from the joystick and a foot pedal (No. 50-8020-00, Happ Controls, Elk Grove, IL) for the SHAFT. The stock potentiometer was removed from the foot controller and replaced with a 50 kQ linear potentiometer (No. 53CS, RV4NAYSD 503A, Clarostat Manufacturing Co., Inc., Dover, NH). The foot controller was connected to the computer through the left joystick port by means of a 5-pin DIN connector using pins 1 (comparator input, right-left), 3 (GND), and 5 ( + 5 VDC).
Test Descriptions Pursuit Meter III.-The
device described here is a programming and hardware modification of the Pursuit Meter I1 (Ferslew, et al., 1982). The computer generates a black sine wave on the monitor screen from left to right. Although the number of possible wave fronts that can be generated is large, only a simple sine wave pattern is used in this device because it has a high degree of predictabhty which facilitates the subject's performance (Ferslew, Manno, Manno, Hubbard, & Vekovius, 1783). Subjects are required to track the sine wave using the joystick controller. The subject's wave is in red and the joystick controls the vertical position of the subject's wavefront. The vertical position of that wave is directly related to the movement of the joystick. The speed of horizontal movement and horizontal position are controlled by the computer program. The computer compares the position of the subject's sine wave to the reference sine wave once in every vertical column. The absolute value of the difference in positions is summed over the entire sweep (320 vertical columns) and constitutes the error score for that trial. the task so lower scores The score reflects the subject's inability to indicate better performance. Presentation of 1 sweep (1 complete sine wave pattern across the width of the monitor) is 70 sec. in duration (0.1 cycleslsec.). Each subject's results are printed to the hard copy device after every sweep and the mean of the five sweeps is printed at the culmination of that session. The pursuit-tracking task requires the integration of a number of cognitive and psychomotor tasks such as reaction time, visual perception, and fine motor coordination and is believed to measure attentive motor performance (Hughes & Forney, 1964). Simultaneous Hand and Foot Eackzng task.-A divided-attention task involves the simultaneous performance of two or more subtasks. The SHAFT described here is the combination of two tracking tasks (Fig. 1).The primary task is the PM I11 described above. The secondary task is a simple tracking task that uses a foot control for the subject's input. The foot-tracking task (FTT) requires the subject to maintain the position of a horizontal bar presented below the PM I11 sine wave on the computer monitor within a given range. That range is defined by two vertical lines within a larger response
G. W.KUNSMAN, ETAL. T
nJ
Joystick
rY
Controller
Indicator line is blue when in range
d
Foot
I
rP
Joystick
Controller
lndicator line is red when out of range
FIG.1.
Divided attention task
area also bound by two vertical lines. The target range moves within the larger area four tirnes/sweep according to a predetermined pattern. That pattern changes with each sweep within a session but does not vary between sessions. The FTT, despite being considered a secondary task, is scored to
VALIDITY OF PSYCHOMOTOR DEVICES
259
assure each subject's compliance with both aspects of the test. The score is reflective of the time spent out-of-range, with a maximum score of 321. The subject's indicator is a red line when out-of-range which changes to a blue line when the leading edge of the line is within the defined range. The position of the indicator is sampled each time the computer plots a point of the sine wave and, if the indicator is not within the range, the error score is increased by 1. The degree or extent out-of-range is not considered in this score, but it is simply a measure of on-target or off-target. Error scores are printed separately for each subtask and, as in the PM 111, a set of five complete sweeps of the sine wave constitutes a single session. The combination of the two traclung tasks places the subject in a situation in which the capacity to absorb and respond to all relevant information is assessed. Moskowitz (1984) suggests that placing subjects in a situation requiring sequential timesharing of attention between two or more information sources is a necessary test in the evaluation of behavioral drug impairment because divided attention tasks are frequently highly sensitive to drug effects.
Procedure Each task was evaluated in a separate study. The procedure for each study was identical. Ten subjects were tested on each task. Three of the female subjects were tested on the SHAFT and the other two were tested on the PM 111. Subjects were required to be naive to the task on which they were tested. After obtaining signed informed consent, the subject was given a visual demonstration of the task in operation while the purpose and scoring of the test was explained. Subjects were not allowed practice trials before the study began. Each subject tested for a total of 15 sessions (75 total sweeps) over a 3-day period. Each testing period was approximately 1 hr. in duration and the testing periods occurred on three nonconsecutive days over a 2- or 3-week period. Subjects were tested at the same time of day for each testingperiod. Each sweep was 70 sec. in duration and one session required approximately 6 min. Subjects were given a 5-min. rest between sessions on each testing day. Pursuit Meter III Analysis of the pursuit meter data is based on the mean score for each of the 15 sessions (5 sweeps/session). The mean error score for the 10 subjects in this phase of the study is plotted in Fig. 2 and tabulated in Table 1. The plot of means depicts a learning curve that does not reach an asymptote. Performance improved rapidly over the first few sessions and shows a continued gradual improvement over the period of the study. A two-way (session by subject) analysis of variance was performed on = 38.55, the 15 sessions. The main effect of session was significant (F,,,,,,
260
G. W. K U N S M A N , ETAL.
p < .001), but the main effect of subject was not s ~ ~ n i f i c a n(F,,,,, t = 1.17, p = .38). A significant interaction of subject x session was also observed (F,,6,600 = 2.51, p
