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Premotor and Motor Reaction Time as a Function of Movement Extent,Pierre P. Lagassea & Keith C. Hayesa

a Department of Exercise Science, University of Massachusetts — AmherstPublished online: 13 Aug 2013.

To cite this article: Pierre P. Lagasse & Keith C. Hayes (1973) Premotor and Motor Reaction Time as a Function of Movement Extent, , Journal of Motor Behavior, 5:1, 25-32, DOI: 10.1080/00222895.1973.10734947

To link to this article: http://dx.doi.org/10.1080/00222895.1973.10734947

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Journal of Motor Behavior 1973, Vol. 5,No. 1,25-32

PREMOTOR AND MOTOR REACTION TIME AS A FUNCTION OF MOVEMENT EXTENP, 2

Pierre P. Lagasse and

Keith C. Hayes

Department of Exercise Science University of Massachusetts- Amherst

The effects of variations in extent of movement on fractionated reaction times (RTs) were studied in 18 male Ss. The means of total RT, premotor RT and motor RT (Weiss, 1965) did not change significantly under the two treatment conditions involving variations in extent of elbow flexion in response to a visual stimulus. These results supported earlier work of Brown and Slater-Hammel (1949), but apparently conflicted with recent data reported by Williams (1971 ). A differential effect of practice on the two tasks was identified and postulated as a possible factor contributing to the conflict among previous research findings.

Hathaway, in 1932, was one of the first investigators to recognize the advantages of an experimental strategy enabling discrete and simultaneous differentiation of the central and peripheral components of reaction time (RT). Several years later, Weiss (1965) formally fractionated total RTs into premotor RT and motor RT components. These components corresponded to central nervous system delays occurring before the onset of muscle action potentials (MAPs), and peripheral or muscular delays occurring from the first MAPs to the

1 The computer time for this project was provided through the facilities of the

Computer Center, University of Massachusetts.

2 The authors gratefully acknowledge the help and guidance afforded by Dr. W. Kroll of the University of Massachusetts.

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Pierre P. Lagasse and Keith C. Hayes

beginning of overt movement. The fractionation technique of Weiss ( 1965) permits determination of the locus of temporal changes attributable to the experimental condition, information which cannot be obtained from total RT alone.

Several years prior to development of the technique of fractionating RTs, Brown and Slater-Hammel (1949) reported that total RT was not dependent on movement extent. The movements employed were limited to a linear displacement of the hand and only varied in extent between 2.5 and 40 em. No difference was found for total RT under these conditions. In apparent contradiction to the results of Brown and Slater-Hammel ( 1949) were more recent data reported by Williams ( 1971) for much larger movements. Based on a comparison among several studies concerned with both task complexity and extent, and supported by his own experimental evidence, Williams ( 1971) presented an argument for longer total RT attributable to increased movement extent. In view of this conflict, the present study was designed to investigate further the effect of variations in extent of movement upon RT. By using gross differences in movement extent, it was possible to obtain a more thorough test of the effect of movement extent on RT. Moreover, by using the fractionated RT technique of Weiss ( 1965). the contribution of the pre motor and motor components of RT could be quantified.

Method Subjects. Male undergraduate and graduate students (N=18) attending

the University of Massachusetts participated in the study. They were not paid for their time. The mean age was 23.2 yr. and the mean height was 69.8 in.

Apparatus. The visual stimulus for each RT trial was obtained from an N E-41 neon lamp mounted in a black wood panel located 44 in. from S who was seated at a table. When the light came on, a deflection was recorded on an oscillograph (Beckman Dynograph, Type R) with paper speed set at 250 mm/sec. As S lifted his hand from the table in response to the stimulus, a microswitch was activated causing a further deflection to be recorded on the Dynograph. Total RT was obtained by measuring the interval between the two deflections and convertin!~ to time from the known paper speed. Fractionation of total RT was permitted by recording on the Dynograph the onset of MAPs from Beckman silver silver-chloride electrodes located over the motor point of the biceps brachii. The interval from the deflection caused by presentation of the stimulus to the change in the EMG represented the premotor RT. Motor RT was obtained by subtracting premotor RT from total RT.

Procedures. For each RT trial a preparatory signal of "ready" was given and the visual stimulus followed at time intervals between 1 and 3 sec .

•

Preparatory intervals had equal probability of occurring, their sequence of presentation was selected at random, and they were varied and controlled by a Hunter Model 111-C decade interval timer.

Movement times (MT) were also obtained from the Dynograph. Two deflections were recorded, the first caused by activation of the microswitch at the commencement of movement (end of RT) and the second produced by activation of a second microswitch located on a freely moveable wooden hinge

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Reaction Time and Movement Extent

at a point 90 deg. through the arc of movement. MTs were calculated from the distance between the two deflections.

Ss attended two testing sessions on separate days. At each sessionS sat with his fist placed on a microswitch and the ulnar aspect of his forearm resting on the table. The angle between his arm and forearm was 155 deg. Fractionated RTs were recorded under two different conditions both of which consisted of simple RTs, i.e., which did not involve any choice of task. Task A consisted of 25 trials of a simple RT to a visual stimulus and involved a rapid withdrawal of

' the fist from its resting position on the microswitch. The 25 trials of Task B were initiated in the same way as Task A but continued as a rapid flexion of the forearm through a full range of 140 deg. After 90 deg. of flexion, S's fist hit the second microswitch mounted on the freely moveable hinge. Tasks A and B differed only in the extent of movement.

To provide a statistical check against discontinuity of movement in Task B, a further 10 trials of a rapid val itional movement, Task C, were included. This movement was initiated by S after indicating that he was ready, involved the same movement extent as Task B, and was not preceded by the visual stimulus. Order of presentation of the three treatment conditions was determined from a balanced Latin square to minimize sequence effects.

Results Reliability. Prior to analysis of the main treatment effects, reliability

estimates for all parameters were secured through an intraclass correlation technique (Lindquist, 1956). The analysis is presented in Table 1. RT parameters for Task B in all cases demonstrated higher reliability t.han for Task A. This was due mainly to the larger inter-S variance for Task B.

Day effects. A partially-nested ANOVA revealed that the difference between Day 1 and Day 2 means was not significant, F(1, 17)=4.01,p>.05, for the total RT of Task A. For total RT of Task B, the large extent movement, a significant difference, F(1, 17)=16.83, p<.01, between Day 1 and Day 2 was found. Motor RT for Tasks A and B did not change significantly, p>.05, from Day 1 to Day 2. Similarly for premotor RT of Task A, no significant difference, F(1,17)=2.31,p>.05, was found between Day 1 and Day 2. A significant

. . difference, F(1,17)=11.06,p<.01, was revealed, however, for premotor RT of Task B between Day 1 and Day 2. The improvement in total RT for Task B from Day 1 to Day 2 was therefore due to the premotor RT component, as the MT remained constant from Day 1 to Day 2. Further analysis through the use of orthogonal polynomial coefficients disclosed no significant trend between Trials within either Day 1 or Day 2. On the basis of the above evidence, only the second day values of total RT, premotor RT, motor RT, and MT were analyzed for the main treatment effects.

Movement extent. A partially-nested ANOVA testing for differences between the total RT means of Task A and Task B revealed no significant differences, F ( 1, 17)=.00,p>.05. Analyses of the fractionated components similarly revealed that motor RT, F ( 1, 17)=.51 ,p>.05, and pre motor RT, F(1, 17)=.90,p>.05, for Task B were not significantly greater than those of Task

A.

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~ -o CXl -· ro

Table 1 ""' ""' ro

Means, SDs and Reliability Coefficients for Fractionated Reaction Time Components and Movement Timesa -o •

r ru tO

Task A simple RT Task B simple RT and movement Task C ru V> V> ro ru

Drnm ...... +,.., .... " 11 .......... or Total Pren1otor rv1ulor Total • • • Movement ' I IJI IU LUI lVI U l IVIOVemenl 0..

RT RT RT RT RT RT time time 7\ ro -· .... ::r

- ("")

X Day 1 178 61 239 182 64 246 131 128 •

I ru

SD Day 1 32 12 34 37 15 37 12 14 -< ro - V>

X Day 2 171 59 230 169 61 230 131 128

SD Day 2 30 12 33 30 1 1 30 12 13

R .56 . 75 . 73 .81 .83 .77 .83 .88

Days Error 45 11 48 46 9 60 9 13 Mean Square

Trials Error 173 13 179 143 11 141 12 9 Mean Square

True Score Mean Square 33 17 73 111 25 112 24 38

a all values in msec. except for intraclass correlation coefficients (N= 18)

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Relationships among RT components. The matrix presented in Table 2 shows significant correlations among many of the variables. In order to further examine these relationships, the data were subjected to a Kaiser orthogonal varimax rotation of principal axes (Kaiser, 1959). This factor analysis enabled identification of just two discrete factors with Eigen values greater than one. The vector loadings suggested independence of motor RT, which loaded heavily on Factor 2, from premotor RT and total RT, which loaded together on Factor 1. These two factors together accounted for 88% of the total variance.

Discussion The results of the present study supported the conclusions of Brown

and Slater- Hammel ( 1949) that total RT is independent of movement extent, and appeared to conflict with the findings of Williams ( 1971) who found RT for large extent movements to vary with the extent of the task. The reason for this discrepancy is unclear, but Williams (1971) states that the differences he found "might be accounted for by differences in experimental procedures, emphases, and instructions (p. 50)" of the studies he cited. Another possibility resides in the effect of practice. The present results demonstrated a significant decrease in total RT and premotor RT between days for the large-extent Task B which was not paralleled by premotor RT and motor RT for the small-extent Task A. This may be interpreted as a learning effect. Since practice appeared to have

•

differential effects on the two tasks, discrepancies in the previously-cited investigations may have been due to differences in the number of days or trials

• g1ven. Longer RTs attributable to increased extent of the movement,

regardless of any practice effects, have been accepted by Williams ( 1971) as support for the "memory drum" theory (Henry & Rogers, 1960). The present results appeared not to conform to the Henry-Rogers model which predicts longer total RT as a result of increased complexity and/or extent of the task. It would seem that movement extent is not a component of complexity, nor does it contribute to the duration of total RT when sufficient practice trials have been given. One possible line of reasoning for this suggests that in movements of varying extent; a variation in the force requirement of the functioning muscle group is accommodated within one "program". In complex movements, however, where a change in direction of movement, and thus in muscle groups, is involved, additional "subroutines" must be added to the program, increasing the programming time.

When the present findings are viewed in the broader context of information capacity of the human motor system, certain other features emerge. Ever since the classic work of Woodworth ( 1899) it has been known that the accuracy of a quick movement decreases with extent, and that important interrelationships exist among extent, speed, and accuracy. The "index of movement difficulty" (I D) was, in fact, formulated by Fitts (1954) to describe, in information-theory terms, the relationships among these components. Furthermore, Fitts generated experimental evidence in support of his hypothesis that the channel capacity of a motor system in a task specified by limb, muscle, and behavior characteristics is independent of average extent and of specified

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(.;) 0 Table 2

Correlation Matrix and Eigen Vector Loadings for Fractionated Reaction Time Components

Task A Total RT 1

Premotor RT 2

Motor RT 3

Task B

Total RT

Premotor RT

Motor RT

%Variance

Eigen Value

4

5

6

1

* * denotes significance, p < .01.

2 3 •

.889** . 704 * *

.303

4

. 750**

. 708**

.453

5

.615**

.716**

.155

.902**

6

.418

.091

. 739**

.367

·.066

Vector I

.798

.904

.252

.882

.946

.002

53%

3.7

Loadings II

.!:>20

.120

.907

.300

:105

.936

35%

1. 5

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r "' (.Cl

"' V> V> ro

"' :::J Cl..

7\ ro -· .-+ ::::r 0 •

I

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Reaction Time and Movement Extent

permissible variability (movement tolerance). While it is necessary to emphasize that the present results were obtained using discrete tasks as opposed to the successive movements of Fitts, and that movement tolerance was not specified, it may be suggested that the I D did not alter to any important degree. Sacrifice of accuracy for extent could easily have effected a constant I D. Even with the assumption of constant difficulty violated, little change in RT would have been expected, as the results of Fitts and Peterson ( 1964) have shown that it is MT that is primarily affected and that RT stays relatively unchanged. It seems probable that in the present study the maximum information processing capacity of the motor system did not impose any restriction on the response characteristics.

Traditionally, when lengthening of total RT has been observed it was thought to reflect central nervous system delays. Implicit in this reasoning is the acceptance of invariant temporal characteristics of muscle contraction or, in other words, a constant motor RT. Motor RT failed to show significant differences between means for Task A and Task B under the present experimental conditions, and the assumption can, therefore, be considered appropriate for movements of varying extent. However, such a situation does

' not hold for all experimental conditions, as was demonstrated by Schmidt and Stull (1970) and Weisendanger, Schneider, and Villoz (1969). The constancyof the motor RT between tasks in the present study is also reflected in the factor analysis where premotor RT and total RT loaded together on one factor and the motor RT loaded on a separate, orthogonal factor. The factor analysis substantiates the independence of the components, across Ss reported by Botwinick and Thompson (1966) and Schmidt and Stull (1970). Demonstration of nonsignificant differences between treatment means for premotor RT is interpreted as further, more rigorous, evidence against the argument for longer central processing delays due to increased task extent.

References Botwinick, J. & Thompson, L.W. Premotor and motor components of reaction

time. Journal of Experimental Psychology, 1966, 71, 9-15. . . •

Brown, J.S. & Slater-Hammel, A.T. Discrete movements in the horizontal plane as a function of their length and direction. Journal of Experimental Psychology, 1949, 38, 84-95.

Fitts, P.M. The information capacity of i:he human motor system in controlling the amplitude of movement. Journal of Experimental Psychology, 1954, 4 7, 381-391.

Fitts, P.M. & Peterson, J.R. Information capacity of discrete motor responses. Journal of Experimental Psychology, 1964, 67, 103-112.

Hathaway, S. Some characteristics of the electromyograms of quick voluntary muscle contractions. Proceedings of the Society for Experimental Biology and Medicine, 1932, 30, 280-281.

Henry, F.M. & Rogers, D.E. Increased response latency for complicated movements and a "memory drum" theory of neuromuscular reaction.

Research Quarterly, 1960, 31, 448-458.

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Pierre P. Lagasse and Keith C. Hayes

Kaiser, H. F. Computer program for varimax rotation in factor analysis. Educational and Psychological Measurement, 1959, 19, 413-420.

Lindquist, E. F. The design and analysis of experiments in psychology and education. Boston: Houghton Mifflin, 1956.

Schmidt, R.A. & Stull, G.A. Premotor and motor reaction time as a function of preliminary muscular tension. Journal of Motor Behavior, 1970, 11, 96·11 0.

Weiss, A.D. The locus of reaction time change with set, motivation, and age. Journal of Gerontology, 1965, 20, 60-64.

Wiesendanger, M., Schneider, P. & Villoz, J.P. Electromyographic analysis of a rapid volitional movement. American Journal of Physical Medicine, 1969, 48, 17-24.

Williams, L. R. T. Reaction time and large response movements, New Zealand Journal of Health, Physical Education, and Recreation, 1971, 4, 46-52.

Woodworth, R.S. The accuracy of voluntary movement. Psychological Review, 1899, 3 (Monogr. Suppl. 13).

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