Journal of Abnormal ChildPsychology, Vol 6, No. 3, 1978, pp. 325-337
Body Movement and Inattention in Learning-Disable and Normal Children Robert P. Rugel George Mason University Douglas Cheatam and Annette Mitchell Virginia Polytechnic Institute and State University Four experiments were conducted to test various aspects o f an optimal level o f arousal model o f hyperactivity in learning-disabled children. Vigilance performance and level o f body movement were measured while learning-disabled and control children performed in an auditory vigilance task. The results suggested that body movement increased throughout the vigilance task, inereased rates o f external stimulation result in decreased level o f body movement, and learningdisabled children differed from controls in showing higher levels o f body movement and poorer vigilance performance. The results were discussed h7 terms o f changes in arousal level and compensatory stimulus-seeking behavior. Fiske and Maddi (1961), Berlyne (1960), and Schultz (1965) all suggest that organisms experience a subjective state that can be described along a boredomexcitation continuum. This internal state is variously referred to as arousal level or activation level and is determined by external and internal sources of stimulation. External sources of stimulation refer to such things as stimulus intensity, rate of stimulus change, stimulus complexity, and stimulus novelty. Internal sources of stimulation refer to such things as muscular activity and cognitive activity including fantasy. According to these theorists, organisms seek to maintain an optimal level of arousal that is experienced as comfortable. This internal level of arousal has motivating properties and operates according to a homeostatic model. If level of arousal is too high discomfort in the form of overexcitement is experienced and the organism seeks to lower his level of arousal by withdrawing from sources of stimulation. If level of arousal is too low discomfort in the form of boredom is experienced, which causes the organism to seek out additional sources of stimulation. Manuscript received in final form February 6, 1978. 325 0091-0627/78/0900-0325505.00/0 9 1978 P l e n u m Publishing Corporation
326
Rugel, Cheatam, and Mitchell
This homeostatic arousal model has relevance in understanding the behavior of children called "hyperactive" or "learning disabled." Two of the primary characteristics of such children are attentional deficits and increased body movement (Sroufe, 1973; Pope, 1970; Dykman, 1970). The proposition that generated the studies presented below is that the attentional deficit of the learning-disabled child contributes to his hyperactivity. It is proposed that the learning-disabled child engages tasks requiring sustained attention in the usual fashion but becomes inattentive to that task especially quickly. As his attention decreases, the task becomes increasingly unavailable to him as a source of stimulation, with a resulting drop in his internal level of arousal. When the drop becomes intense enough the child becomes uncomfortable and motivated to seek other sources of stimulation. Much of the stimulus-seeking behavior of the learning-disabled child involves body activity, in part because body activity usually occurs in moving from an environmental event that is not useful as a source of stimulation to one that is. In addition, body movement itself is a source of stimulation since it creates proprioceptive and visceral feedback. A similar analysis has been proposed by Zentall (1975). A vigilance task was chosen to examine these proposed relationships since sustained attention is necessary both in the vigilance task and in school situations where the hyperactivity of learning-disabled children is frequently observed. The typical pattern of response of subjects in a vigilance task is to miss more signals at the end of the task than at the beginning, thus demonstrating a vigilance decrement. Stroh (1971) accounts for this decrement in terms of a shift in observing responses away from the relevant stimuli in the task onto irrelevant stimuli. Many factors contribute to this shift, including habituation of the central nervous system response to the relevant stimuli as they lose their novelty value, extinction of the observing response since signals occur infrequently, increased cautiousness of responding throughout the tasks, as well as others. Since learning-disabled children are observed to show greater vigilance decrements than normals, more shifts in observing responses presumably occur. With respect to the arousal model discussed above, two hypotheses are proposed. Hypothesis 1 states that when subjects become underaroused they will increase their level of body movement. With respect to the vigilance task, the overall lack of stimulation in the task will result in increasing underarousal and compensatory increases in body movement throughout the task. Hypothesis 2 states that attention (as measured by vigilance performance) will effect arousal level and subsequent body movement. When attention is directed to the stimuli relevant to performance in the vigilance task, these stimuli will be useful in maintaining arousal level. When attention switches away from the relevant stimuli, little else externally is available in the vigilance situation to maintain arousal level. The result will be increased underarousal and compensatory body movement. Thus capacity for sustained attention is seen as a determinant of arousal level and subsequent body movement. These hypotheses were derived
Body Movement and Inattention
327
post hoc from Experiment I presented below and tested in Experiments II, III, and IV. Experiment I was conducted to investigate the attentional and skinconductance responses of learning-disabled and normal children in an auditory vigilance task.
EXPERIMENT I
Method
Sub/ects The learning-disability sample consisted of 38 children who had been diagnosed "learning disabled" (LD) by school personnel based upon the state criteria for learning disabilities. In all cases these children had a reading level 1 year or more below the level expected based on the child's chronological age. These subjects were matched on age, sex, and intelligence with 24 control subjects. Each control subject was from the same classroom as the LD child IQ scores used for matching subjects were from group intelligence tests such as the Lorge-Thorndike and SRA tests. The mean IQ of the LD and control groups was 97 and 98, respectively, with a range of 85 to 129. The mean age of both groups was 10.4, with a range of 7.2 to 12.4 and 7.6 to 12.0, respectively.
Vigilance Task The children listened through earphones to a tape recording of the digits one through nine presented at the rate of one per second. When they heard the number six they were to respond by pressing an event marker held in their preferred hand. The vigilance task was divided into four 789 quarters. The number of sixes occurring in each of the four quarters was seven, nine, six and seven, respectively.
Skin Conductance Subjects performed the vigilance task while enclosed in a 4' X 4' • 7' featureless enclosure. All visual stimuli other than the homogeneous brown sides of the enclosure were eliminated. Extraneous auditory stimulation was prevented by the earphones used in presenting the numbers of the vigilance task. Skin resistance levels were recorded from the subject's nonpreferred hand using elec-
328
Rugel, Cheatam, and Mitchell Table I. Percentage of Signals Correctly Identified During
Each Quarter of the VigilanceTask in Experiment I Quarters 1
R
LD C
2
SD
X
3
SD
X
4
SD
X
SD
7 3 . 5 17,3 56.1 29.7 59.7 31 51.7 30.6 81.8 19.9 72.7 23.5 75.0 21.1 67.8 27.3
trodes and GSR amplifier of a Lafayette 4-channel datagraph. The electrodes were brass, plated with copper, nickel, and chrome. The amplifier had a response frequency of 0 to 40 Hz. Resistance levels were sampled every 3 minutes during the vigilance task and converted to log micromhos.
Results
Vigilance Performance
The proportion of signals correctly identified during each quarter of the vigilance task was analyzed. A significant group effect, F(1,59) = 6.03, p < .05, a significant quarters effect, F(1,77)= 8.47, p < .01 and a nonsignificant interaction were discovered. Table I indicates that the vigilance performance of learning-disabled subjects was poorer than that of control subjects throughout the task. Skin Conductance
Analysis of the skin conductance data revealed neither a group effect nor a group by quarters interaction. The quarters effect was significant, F(11,638) = 9.55, p < .01. All subjects showed increases in skin conductance throughout the course of the vigilance task. Discussion of Experiment I
The vigilance decrement observed in all subjects in the present task is consistent with other research indicating that subjects become increasingly inattentive throughout vigilance tasks. The poorer vigilance performance of learningdisabled subjects is also consistent with other literature indicating an attentional deficit in these children (Anderson, Halcomb, & Doyle, 1973). However, the rise in skin conductance for all subjects during the task was unexpected since adults in this task and similar tasks (Stroh, 1971) show skin conductance decreases indicative of increasing drowsiness. However, the observed skin conductance in-
Body Movement and Inattention
329
crease is consistent with a similar increase found with adult subjects in stimulusdeprivation studies (Schultz, 1965). The skin conductance increase is also consistent with Berlyne's prediction (Berlyne, 1960, p. 189) that skin conductance levels would rise during monotonous tasks. Since most extraneous sources of stimulation were removed during the task as a result of the earphones and the enclosure and since the only source of stimulation was the auditory presentation of the numbers, it was assumed that as children became inattentive to the numbers the absence of external stimulation resulted in their being underaroused. The rise in skin conductance was considered a reflection of the discomfort created by the increasing underarousal.
EXPERIMENT II
If the vigilance task in Experiment I creates underarousal then the two hypotheses discussed earlier can be investigated. The prediction based upon hypothesis 1 is that levels of body movement will rise throughout the vigilance task. This is based on the premise that as subjects become underaroused they should become uncomfortable and motivated to seek out other sources of stimulation as they try to maintain their level of arousal. This can be accomplished in at least two ways, both involving body movement. The first is to engage in exploration of the enclosure in search of stimulation. The second is to increase proprioceptive and visceral stimulation by directly increasing body movement. The prediction based upon hypothesis 2 is that learning-disabled children will show quicker and greater body movement increases in the vigilance task. This is based upon the premise that greater inattention results in greater underarousal and therefore in greater levels of body movement.
Method
Subjects Thirteen LD children and 13 control children were selected according to the criterion used in Experiment I. Subjects were matched for age, IQ, and sex, For the learning-disability subjects the mean age was 10.6 with a range of 7.0 to 12.8; for controls the mean age was 10.2 with a range of 7.2 to 12.4. The mean IQ was 96 in each group.
Body Movement Measure Raters unaware of group membership observed the subjects' movement at 1-minute intervals during the vigilance task. Six categories of movement were
330
Rugel, Cheatam, and Mitchell
rated: movement of right and left arms (including hands), movement of fight and left legs (including feet), head movement, and trunk movement. A specific movement was considered in terms of the total range within which that particular movement could take place. For example, if the subject moved his right arm from his right knee ha the direction of his face, the total range of movement was considered to be from the knee to the face. If the actual movement the subject went through was more than 25% of the potential range, then the movement was considered "large." If the actual movement was less than 25% the movement was considered moderate. "No movement" was also recorded. Two 1 or 0 points were assigned to "large," "moderate," or "no movement," respectively, Total body activity per observation was the sum of the points in the six categories. Mean body movement levels during each quarter of the vigilance task were obtained by averaging the observations made during that quarter. Using this method coefficients of the interrater reliability were r -- .95.
Results
Vigilance Performance An attentional deficit in the vigilance task for the learning-disabled children relative to normals was found as can be seen ha Table II. Analysis of variance revealed a significant groups effect, F(1,24) = 8.64, p < .01, a significant quarters effect, F(3,72) = 4.48, p < .05, and a nonsignificant interaction.
Body Movement The predicted increase in body movement over quarters occurred, F(3,72) = 7.84, p < .01. The groups effect was not significant; however, there was a significant groups by quarters interaction, F(3,72) = 4.37, p < .01 indicating greater body movement for learning-disabled subjects toward the end of the task.
Table II. Percentage of Signals Correctly Identified During Each Quarter of the Vigilance Task in Experiment II Quarters 1
2
SD LD C
75.6 85.4
X
3
SD
X
4
SD
.X
14.8 61.8 24.2 59.3 29.8 43.2 12.4 75.3 15.5 79.1 20.1 76.6
SD 34.2 23.3
Body Movement and Inattention
331
Discussion of Experiment II
These results support hypothesis 1, which predicts increases in body movement during the vigilance task as subjects become increasingly underaroused and attempt to maintain an optimal level of arousal by increasingly engaging in stimulus-seeking activities involving body movement. Support is also provided for hypothesis 2 since learning-disabled children showed quicker and larger body movement increases toward the end of the task while also showing a greater attentional deficit. However, this relationship may be only correlational. The occurrence of both the attentional deficit and the increased body activity together does not necessarily indicate that the attentional deficit was responsible for the increased body activity. A direct manipulation of the attentional variable is necessary to demonstrate this conclusively. EXPERIMENT III
The purpose of Experiment III was to manipulate the attentional variable. Experiments I and II indicated that a vigilance task that involves infrequent occurrences of the signal digit results in a vigilance decrement and an increase in body activity. According to Stroh (1971), increases in rate of signal presentation will result in increased attention as measured by vigilance performance. According to hypothesis 2, increased attention should make more of the numbers in the vigilance task available to thesubject as sources of stimulation and hence decrease the need for additional stimulation via body movement. If different levels of sustained attention are achieved as a result of different signal frequencies then hypothesis 2 would predict different levels of body movement. In Experiment III the level of body movement occurring under different levels of stimulation was investigated. Method
Subjects The subjects were 30 elementary school children who were randomly assigned to one of three groups; Gp 7Q, Gp 28Q, or Gp 100Q. The mean ages of the three groups were 10.4, 10.3, and 10.4, respectively. The age ranges were 9-6 to 11-4, 9-5 to 11-6, and 9-6 to 11-4.
Procedure Subjects in Gp 7Q performed the auditory vigilance task as described above. The signal number occurred 28 times at the rate of 7 per quarter. In Gp
332
Rugel, Cheatam, and Mitchell
28Q the signals occurred 112 times at the rate of 28 per quarter and in Gp 100Q the signals occurred 400 times at the rate of 100 per quarter.
Body Movement Body movement was rated as described above with the exception that arm movement was rated without hand movement and leg movement was rated without foot movement.
Results
Vigilance Performance The analysis revealed a significant trials main effect (F(3,81) = 3.65, p < .05); the groups effect was nonsignificant;however, the groups by quarters interaction approached significance (F(6,81) = 2.02, p < . 1 0 ) . Figure 1 indicates a trend toward decreased vigilance performance in the 7Q group over quarters of the vigilance task.
Body Movement The analysis revealed a significant groups effect, F(2,27) = 5.91, p < .01, a significant quarters effect, F(3,81) = 20.63, p < .01, and a significant groups by quarters interaction, F(6,81) = 2.22, p < .05. Figure 2 indicates an inverse
90 80 r
m
z70
,.,.. ~ 0
"-~60 *-
50 I
1
I
2
I
3
I
4
QUARTERS Fig. 1. Percentage of signals correctly identified during each quarter of the vigilance task.
Body Movement and Inattention
I--z
o
1.1 1.0 .9 .8 .7 .6 .5 .4 .3 .2 .1
333
~
TQ 28Q
IOOQ
I 1
i 2
i 3
i 4
QUARTERS
Fig. 2. Body movement during each quarter of the vigilance task. relationship between signal frequency and body movement. The greater the signal frequency, the smaller the amount of body movement. Discussion of Experiment III The results indicating an inverse relationship between signal frequency and body movement are consistent with hypothesis 1. If one views each signal as an external stimulus that is useful in maintaining level of arousal, then the greater amount of external stimulation provided by the high frequency conditions resulted in higher internal levels of arousal and less need for additional stimulus seeking as reflected in body movement. However, the results are not clearly supportive of hypothesis 2. According to this hypothesis, attentional differences should be correlated with and actually determine levels of body movement. Group 7Q did show a trend toward differing from groups 28Q and 100Q on the vigilance measure; however, these latter groups did not differ from one another as both groups performed near asymptote. It is possible that groups 28Q and 100Q did differ in degree of attention but that the vigilance measure is not sensitive to attentional differences above signal rates of 28 signals per quarter. An alternate explanation is that attentional differences are not as important a determinant of body movement levels as hypothesis 2 would suggest.
EXPERIMENT IV
Experiment IV was conducted to compare the performance of learningdisabled and normal children under the high and low rates of signal frequency.
334
Rugel, Cheatam, and Mitchell
Sub/ects The subjects were 32 children diagnosed learning-disabled and 32 control children matched for age, IQ, race, and sex. The mean age of both groups was 9.9 with a range of 8.5 to 11.7. The mean IQ of both groups was 101 with a range of 85 to 120.
Procedure Sixteen LD and 16 control subjects performed the vigilance task in the 7Q condition while the other 16 subjects performed the vigilance task in the 100Q condition.
Body Movement Body movement was rated as described in Experiment III.
Results
Vigilance Performance Two-way analysis of variance revealed a significant main effect for the signal frequency condition, F(1,60) = 14.4, p < .01, indicating that the high signal frequency condition did result in superior vigilance performance. A significant quarters effect, F(3,180) = 14.9, p < .01, and a significant signal frequency by quarters interaction, F(3,180) = 4.3, p < .01, were also found. Figure 3 indicates that the quarters effect reflects the typical vigilance decrement and the signal frequency by quarter interaction is due to a third-quarter recovery in both 7Q groups. No group main effect or a group by signal frequency interaction was found, indicating no learning disability-control group differences.
Body Movement A repeated-measures analysis of variance revealed a significant main effect for the signal frequency condition, F(1,100) = 20.1, p < .01, a significant group main effect, F(3,180) = 46.4, p < .01, and a group by quarters interaction, F(3,180) --- 5.4, p < .01. Figure 4 indicates that all subjects showed increases in body movement throughout the task and that the high signal frequency condition resulted in an overall reduction in level of body movement. In addition, Figure 4 indicates that learning-disability subjects were higher in body movement in both frequency conditions. The Duncan Multiple Range test indicated that the signi-
BodyMovementand Inattention
335
90 I,-z
High FrequencyControl
~ 80
High FrequencyLD 70
~owFrequencyControl
.=.
z
60
,ia
FrequencyLD
n
50
I
i
1
I
I
2 3 QUARTER
4
Fig. 3. Percentage of signals correctly identified during each quarter of the vigilance task.
lib /
.,is/""~-Low FrequencyLD
3
,imoo,O~ o~176176176176176
/
/ 2
/,~Low FrequencyControl
~/ " ~ H i ,0"g. . . .h. .
.0
Frequency,LD
o o/" ."~176
1
~ 0
I 1
I I I 2 3 QUARTER
I 4
Fig. 4. Body movement during each quarter of the vigilance task.
336
Rugel, Cheatam, and Mitchell
ficant groups by quarters interaction was due to the relatively greater increase in body moyement by learning-disability subjects during the last two quarters of the vigilance task.
Discussion of Experiment IV
Hypothesis 1 is supported by the finding that the high signal frequency conditions result in lower levels of body movement. It would appear that as one increases the number of meaningful stimuli for the subject to respond to, he will become less underaroused and less active. With fewer meaningful stimuli to respond to greater underarousal and body activity will occur. It is proposed that the following sequence of events take place in the vigilance task. As a result of habituation to task-relevant stimuli, extinction, and other factors mentioned by Stroh (1971), fewer observing responses occur and vigilance performance shows a decrement. With few additional external sources of stimulation available, underarousal takes place and stimulus-seeking behavior begins to occur. This is manifested in the observed increases in body movement. Once stimulus-seeking behaviors begin, they interfere still further with task-relevant observing responses, thus causing still further decrements in vigilance performance. Hypothesis 2 was not supported by Experiment IV. This hypothesis predicted that learning-disabled children would show attentional deficits that would result in greater body movement. Learning-disabled children did show greater body movement levels b u t i n the absence of an attentional deficit. That attentional deficits occur in learning-disabled children is clear from the literature and from Experiments I and II. The failure to find such a deficit in Experiment IV may be due to the atypical third-quarter recovery in vigilance performance in both the learning-disabled and control groups. However, since in Experiments III and IV body movement differences were found in the absence of attentional differences, little support is present for hypothesis 2, which proposes that the attentional deficit is a determinent of the hyperactivity of learning-disabled children. The absence of support for hypothesis 2, however, poses the problem of accounting for the relationship between attention and activity level. Low attention and high activity level frequently occur together in learning-disabled children. They were also related in the present experiments sihce attention went down during the task as body activity went up. One explanation is in terms of the effect of arousal level on both variables. Underarousal creates stimulus seeking, which is manifested in increased body activity. These stimulus-seeking behaviors also interfere with task-relevant activities such as vigilance performance thus contributing to vigilance decrements. Therefore, the frequent correlational relationship found between attention and body activity may be due to a third variable, arousal level, which has effects on both attention and body activity. An explanation is also required for the higher activity level of learning-disabled
Body Movement and Inattention
337
children. The view of the present authors is that learning-disabled children may come into the task with inherently lower arousal levels (Hunter, Johnson, & Keefe, 1972). In addition, they may habituate faster to task-relevant stimuli (Rugel & Rosenthal, 1974), which also contributes to their level of underarousal. Lower arousal levels are characteristic of other populations of deviant children such as children with conduct disorders. Quay (1977) argues that stimulus-seeking behavior may account for many of the deviant behaviors of these children. Thus chronic under-arousal may contribute to a variety of disorders of childhood.
REFERENCES
Anderson, Halcomb, & Doyle. The measurement of attentional deficits. Exceptional Children, 1973, 39(7), 534-538. Berlyne, D. E. Conflict, arousal and curiosity. New York: McGraw-Hill, 1960. Dykman, R. A., Ackerman, P. T., Ctements, S. D., & Peters, J. E. Specific learning disabilities: An attentional deficit syndrome. In H. Myklebust (Ed.), Progress in learning disabilities, New York: Grune & Stratton, 1971. Eiske, D. W., & Maddi, S. R. Functions of varied experience. Homewood, Illinois: Dorsey, 1961. Hunter, E. J., Johnson, L. C., & Keefe, F. B. Electrodermal and cardiovascular responses in nonreaders. Journal of Learning Disabilities, 1972, 5, 187-197. Pope, L. Motor activity in brain injured children. American Journal of Orthopsychiatry, 1970,40, 15. Quay, H. C. Psychopathic behavior: Reflections on its nature, origins and treatment. In F. Weizman & I. Uzgiris (Eds.), The StructuringofExperience, New York: Plenum, 1977. Rugel, R. P., & Rosenthal, R. Skin conductance, reaction time and observational ratings in learning disabled children. Journal of Abnormal Child Psychology, 1974, 2(3), 183-192. Schultz, D. P. Sensory restriction-effects on behavior. New York: Academic Press, 1965. Sroufe, L. A., Sonies, B. C., West, W. D., & Wright, F. S. Anticipatory heart rate deceleration and reaction time in children with and without referral for learning disability. Child Development, 1973, 44, 267-273. Stroh, C. M. Vigilance. The problem of sustained attention. New York: Pergamon Press, 1971. Zentall, S. Optimal stimulation as theoretical basis of hyperactivity. Ameriean Journal of Orthopsychiatry, 1975,45(4), 549-563.
Body Movement and Inattention in Learning-Disable and Normal Children Robert P. Rugel George Mason University Douglas Cheatam and Annette Mitchell Virginia Polytechnic Institute and State University Four experiments were conducted to test various aspects o f an optimal level o f arousal model o f hyperactivity in learning-disabled children. Vigilance performance and level o f body movement were measured while learning-disabled and control children performed in an auditory vigilance task. The results suggested that body movement increased throughout the vigilance task, inereased rates o f external stimulation result in decreased level o f body movement, and learningdisabled children differed from controls in showing higher levels o f body movement and poorer vigilance performance. The results were discussed h7 terms o f changes in arousal level and compensatory stimulus-seeking behavior. Fiske and Maddi (1961), Berlyne (1960), and Schultz (1965) all suggest that organisms experience a subjective state that can be described along a boredomexcitation continuum. This internal state is variously referred to as arousal level or activation level and is determined by external and internal sources of stimulation. External sources of stimulation refer to such things as stimulus intensity, rate of stimulus change, stimulus complexity, and stimulus novelty. Internal sources of stimulation refer to such things as muscular activity and cognitive activity including fantasy. According to these theorists, organisms seek to maintain an optimal level of arousal that is experienced as comfortable. This internal level of arousal has motivating properties and operates according to a homeostatic model. If level of arousal is too high discomfort in the form of overexcitement is experienced and the organism seeks to lower his level of arousal by withdrawing from sources of stimulation. If level of arousal is too low discomfort in the form of boredom is experienced, which causes the organism to seek out additional sources of stimulation. Manuscript received in final form February 6, 1978. 325 0091-0627/78/0900-0325505.00/0 9 1978 P l e n u m Publishing Corporation
326
Rugel, Cheatam, and Mitchell
This homeostatic arousal model has relevance in understanding the behavior of children called "hyperactive" or "learning disabled." Two of the primary characteristics of such children are attentional deficits and increased body movement (Sroufe, 1973; Pope, 1970; Dykman, 1970). The proposition that generated the studies presented below is that the attentional deficit of the learning-disabled child contributes to his hyperactivity. It is proposed that the learning-disabled child engages tasks requiring sustained attention in the usual fashion but becomes inattentive to that task especially quickly. As his attention decreases, the task becomes increasingly unavailable to him as a source of stimulation, with a resulting drop in his internal level of arousal. When the drop becomes intense enough the child becomes uncomfortable and motivated to seek other sources of stimulation. Much of the stimulus-seeking behavior of the learning-disabled child involves body activity, in part because body activity usually occurs in moving from an environmental event that is not useful as a source of stimulation to one that is. In addition, body movement itself is a source of stimulation since it creates proprioceptive and visceral feedback. A similar analysis has been proposed by Zentall (1975). A vigilance task was chosen to examine these proposed relationships since sustained attention is necessary both in the vigilance task and in school situations where the hyperactivity of learning-disabled children is frequently observed. The typical pattern of response of subjects in a vigilance task is to miss more signals at the end of the task than at the beginning, thus demonstrating a vigilance decrement. Stroh (1971) accounts for this decrement in terms of a shift in observing responses away from the relevant stimuli in the task onto irrelevant stimuli. Many factors contribute to this shift, including habituation of the central nervous system response to the relevant stimuli as they lose their novelty value, extinction of the observing response since signals occur infrequently, increased cautiousness of responding throughout the tasks, as well as others. Since learning-disabled children are observed to show greater vigilance decrements than normals, more shifts in observing responses presumably occur. With respect to the arousal model discussed above, two hypotheses are proposed. Hypothesis 1 states that when subjects become underaroused they will increase their level of body movement. With respect to the vigilance task, the overall lack of stimulation in the task will result in increasing underarousal and compensatory increases in body movement throughout the task. Hypothesis 2 states that attention (as measured by vigilance performance) will effect arousal level and subsequent body movement. When attention is directed to the stimuli relevant to performance in the vigilance task, these stimuli will be useful in maintaining arousal level. When attention switches away from the relevant stimuli, little else externally is available in the vigilance situation to maintain arousal level. The result will be increased underarousal and compensatory body movement. Thus capacity for sustained attention is seen as a determinant of arousal level and subsequent body movement. These hypotheses were derived
Body Movement and Inattention
327
post hoc from Experiment I presented below and tested in Experiments II, III, and IV. Experiment I was conducted to investigate the attentional and skinconductance responses of learning-disabled and normal children in an auditory vigilance task.
EXPERIMENT I
Method
Sub/ects The learning-disability sample consisted of 38 children who had been diagnosed "learning disabled" (LD) by school personnel based upon the state criteria for learning disabilities. In all cases these children had a reading level 1 year or more below the level expected based on the child's chronological age. These subjects were matched on age, sex, and intelligence with 24 control subjects. Each control subject was from the same classroom as the LD child IQ scores used for matching subjects were from group intelligence tests such as the Lorge-Thorndike and SRA tests. The mean IQ of the LD and control groups was 97 and 98, respectively, with a range of 85 to 129. The mean age of both groups was 10.4, with a range of 7.2 to 12.4 and 7.6 to 12.0, respectively.
Vigilance Task The children listened through earphones to a tape recording of the digits one through nine presented at the rate of one per second. When they heard the number six they were to respond by pressing an event marker held in their preferred hand. The vigilance task was divided into four 789 quarters. The number of sixes occurring in each of the four quarters was seven, nine, six and seven, respectively.
Skin Conductance Subjects performed the vigilance task while enclosed in a 4' X 4' • 7' featureless enclosure. All visual stimuli other than the homogeneous brown sides of the enclosure were eliminated. Extraneous auditory stimulation was prevented by the earphones used in presenting the numbers of the vigilance task. Skin resistance levels were recorded from the subject's nonpreferred hand using elec-
328
Rugel, Cheatam, and Mitchell Table I. Percentage of Signals Correctly Identified During
Each Quarter of the VigilanceTask in Experiment I Quarters 1
R
LD C
2
SD
X
3
SD
X
4
SD
X
SD
7 3 . 5 17,3 56.1 29.7 59.7 31 51.7 30.6 81.8 19.9 72.7 23.5 75.0 21.1 67.8 27.3
trodes and GSR amplifier of a Lafayette 4-channel datagraph. The electrodes were brass, plated with copper, nickel, and chrome. The amplifier had a response frequency of 0 to 40 Hz. Resistance levels were sampled every 3 minutes during the vigilance task and converted to log micromhos.
Results
Vigilance Performance
The proportion of signals correctly identified during each quarter of the vigilance task was analyzed. A significant group effect, F(1,59) = 6.03, p < .05, a significant quarters effect, F(1,77)= 8.47, p < .01 and a nonsignificant interaction were discovered. Table I indicates that the vigilance performance of learning-disabled subjects was poorer than that of control subjects throughout the task. Skin Conductance
Analysis of the skin conductance data revealed neither a group effect nor a group by quarters interaction. The quarters effect was significant, F(11,638) = 9.55, p < .01. All subjects showed increases in skin conductance throughout the course of the vigilance task. Discussion of Experiment I
The vigilance decrement observed in all subjects in the present task is consistent with other research indicating that subjects become increasingly inattentive throughout vigilance tasks. The poorer vigilance performance of learningdisabled subjects is also consistent with other literature indicating an attentional deficit in these children (Anderson, Halcomb, & Doyle, 1973). However, the rise in skin conductance for all subjects during the task was unexpected since adults in this task and similar tasks (Stroh, 1971) show skin conductance decreases indicative of increasing drowsiness. However, the observed skin conductance in-
Body Movement and Inattention
329
crease is consistent with a similar increase found with adult subjects in stimulusdeprivation studies (Schultz, 1965). The skin conductance increase is also consistent with Berlyne's prediction (Berlyne, 1960, p. 189) that skin conductance levels would rise during monotonous tasks. Since most extraneous sources of stimulation were removed during the task as a result of the earphones and the enclosure and since the only source of stimulation was the auditory presentation of the numbers, it was assumed that as children became inattentive to the numbers the absence of external stimulation resulted in their being underaroused. The rise in skin conductance was considered a reflection of the discomfort created by the increasing underarousal.
EXPERIMENT II
If the vigilance task in Experiment I creates underarousal then the two hypotheses discussed earlier can be investigated. The prediction based upon hypothesis 1 is that levels of body movement will rise throughout the vigilance task. This is based on the premise that as subjects become underaroused they should become uncomfortable and motivated to seek out other sources of stimulation as they try to maintain their level of arousal. This can be accomplished in at least two ways, both involving body movement. The first is to engage in exploration of the enclosure in search of stimulation. The second is to increase proprioceptive and visceral stimulation by directly increasing body movement. The prediction based upon hypothesis 2 is that learning-disabled children will show quicker and greater body movement increases in the vigilance task. This is based upon the premise that greater inattention results in greater underarousal and therefore in greater levels of body movement.
Method
Subjects Thirteen LD children and 13 control children were selected according to the criterion used in Experiment I. Subjects were matched for age, IQ, and sex, For the learning-disability subjects the mean age was 10.6 with a range of 7.0 to 12.8; for controls the mean age was 10.2 with a range of 7.2 to 12.4. The mean IQ was 96 in each group.
Body Movement Measure Raters unaware of group membership observed the subjects' movement at 1-minute intervals during the vigilance task. Six categories of movement were
330
Rugel, Cheatam, and Mitchell
rated: movement of right and left arms (including hands), movement of fight and left legs (including feet), head movement, and trunk movement. A specific movement was considered in terms of the total range within which that particular movement could take place. For example, if the subject moved his right arm from his right knee ha the direction of his face, the total range of movement was considered to be from the knee to the face. If the actual movement the subject went through was more than 25% of the potential range, then the movement was considered "large." If the actual movement was less than 25% the movement was considered moderate. "No movement" was also recorded. Two 1 or 0 points were assigned to "large," "moderate," or "no movement," respectively, Total body activity per observation was the sum of the points in the six categories. Mean body movement levels during each quarter of the vigilance task were obtained by averaging the observations made during that quarter. Using this method coefficients of the interrater reliability were r -- .95.
Results
Vigilance Performance An attentional deficit in the vigilance task for the learning-disabled children relative to normals was found as can be seen ha Table II. Analysis of variance revealed a significant groups effect, F(1,24) = 8.64, p < .01, a significant quarters effect, F(3,72) = 4.48, p < .05, and a nonsignificant interaction.
Body Movement The predicted increase in body movement over quarters occurred, F(3,72) = 7.84, p < .01. The groups effect was not significant; however, there was a significant groups by quarters interaction, F(3,72) = 4.37, p < .01 indicating greater body movement for learning-disabled subjects toward the end of the task.
Table II. Percentage of Signals Correctly Identified During Each Quarter of the Vigilance Task in Experiment II Quarters 1
2
SD LD C
75.6 85.4
X
3
SD
X
4
SD
.X
14.8 61.8 24.2 59.3 29.8 43.2 12.4 75.3 15.5 79.1 20.1 76.6
SD 34.2 23.3
Body Movement and Inattention
331
Discussion of Experiment II
These results support hypothesis 1, which predicts increases in body movement during the vigilance task as subjects become increasingly underaroused and attempt to maintain an optimal level of arousal by increasingly engaging in stimulus-seeking activities involving body movement. Support is also provided for hypothesis 2 since learning-disabled children showed quicker and larger body movement increases toward the end of the task while also showing a greater attentional deficit. However, this relationship may be only correlational. The occurrence of both the attentional deficit and the increased body activity together does not necessarily indicate that the attentional deficit was responsible for the increased body activity. A direct manipulation of the attentional variable is necessary to demonstrate this conclusively. EXPERIMENT III
The purpose of Experiment III was to manipulate the attentional variable. Experiments I and II indicated that a vigilance task that involves infrequent occurrences of the signal digit results in a vigilance decrement and an increase in body activity. According to Stroh (1971), increases in rate of signal presentation will result in increased attention as measured by vigilance performance. According to hypothesis 2, increased attention should make more of the numbers in the vigilance task available to thesubject as sources of stimulation and hence decrease the need for additional stimulation via body movement. If different levels of sustained attention are achieved as a result of different signal frequencies then hypothesis 2 would predict different levels of body movement. In Experiment III the level of body movement occurring under different levels of stimulation was investigated. Method
Subjects The subjects were 30 elementary school children who were randomly assigned to one of three groups; Gp 7Q, Gp 28Q, or Gp 100Q. The mean ages of the three groups were 10.4, 10.3, and 10.4, respectively. The age ranges were 9-6 to 11-4, 9-5 to 11-6, and 9-6 to 11-4.
Procedure Subjects in Gp 7Q performed the auditory vigilance task as described above. The signal number occurred 28 times at the rate of 7 per quarter. In Gp
332
Rugel, Cheatam, and Mitchell
28Q the signals occurred 112 times at the rate of 28 per quarter and in Gp 100Q the signals occurred 400 times at the rate of 100 per quarter.
Body Movement Body movement was rated as described above with the exception that arm movement was rated without hand movement and leg movement was rated without foot movement.
Results
Vigilance Performance The analysis revealed a significant trials main effect (F(3,81) = 3.65, p < .05); the groups effect was nonsignificant;however, the groups by quarters interaction approached significance (F(6,81) = 2.02, p < . 1 0 ) . Figure 1 indicates a trend toward decreased vigilance performance in the 7Q group over quarters of the vigilance task.
Body Movement The analysis revealed a significant groups effect, F(2,27) = 5.91, p < .01, a significant quarters effect, F(3,81) = 20.63, p < .01, and a significant groups by quarters interaction, F(6,81) = 2.22, p < .05. Figure 2 indicates an inverse
90 80 r
m
z70
,.,.. ~ 0
"-~60 *-
50 I
1
I
2
I
3
I
4
QUARTERS Fig. 1. Percentage of signals correctly identified during each quarter of the vigilance task.
Body Movement and Inattention
I--z
o
1.1 1.0 .9 .8 .7 .6 .5 .4 .3 .2 .1
333
~
TQ 28Q
IOOQ
I 1
i 2
i 3
i 4
QUARTERS
Fig. 2. Body movement during each quarter of the vigilance task. relationship between signal frequency and body movement. The greater the signal frequency, the smaller the amount of body movement. Discussion of Experiment III The results indicating an inverse relationship between signal frequency and body movement are consistent with hypothesis 1. If one views each signal as an external stimulus that is useful in maintaining level of arousal, then the greater amount of external stimulation provided by the high frequency conditions resulted in higher internal levels of arousal and less need for additional stimulus seeking as reflected in body movement. However, the results are not clearly supportive of hypothesis 2. According to this hypothesis, attentional differences should be correlated with and actually determine levels of body movement. Group 7Q did show a trend toward differing from groups 28Q and 100Q on the vigilance measure; however, these latter groups did not differ from one another as both groups performed near asymptote. It is possible that groups 28Q and 100Q did differ in degree of attention but that the vigilance measure is not sensitive to attentional differences above signal rates of 28 signals per quarter. An alternate explanation is that attentional differences are not as important a determinant of body movement levels as hypothesis 2 would suggest.
EXPERIMENT IV
Experiment IV was conducted to compare the performance of learningdisabled and normal children under the high and low rates of signal frequency.
334
Rugel, Cheatam, and Mitchell
Sub/ects The subjects were 32 children diagnosed learning-disabled and 32 control children matched for age, IQ, race, and sex. The mean age of both groups was 9.9 with a range of 8.5 to 11.7. The mean IQ of both groups was 101 with a range of 85 to 120.
Procedure Sixteen LD and 16 control subjects performed the vigilance task in the 7Q condition while the other 16 subjects performed the vigilance task in the 100Q condition.
Body Movement Body movement was rated as described in Experiment III.
Results
Vigilance Performance Two-way analysis of variance revealed a significant main effect for the signal frequency condition, F(1,60) = 14.4, p < .01, indicating that the high signal frequency condition did result in superior vigilance performance. A significant quarters effect, F(3,180) = 14.9, p < .01, and a significant signal frequency by quarters interaction, F(3,180) = 4.3, p < .01, were also found. Figure 3 indicates that the quarters effect reflects the typical vigilance decrement and the signal frequency by quarter interaction is due to a third-quarter recovery in both 7Q groups. No group main effect or a group by signal frequency interaction was found, indicating no learning disability-control group differences.
Body Movement A repeated-measures analysis of variance revealed a significant main effect for the signal frequency condition, F(1,100) = 20.1, p < .01, a significant group main effect, F(3,180) = 46.4, p < .01, and a group by quarters interaction, F(3,180) --- 5.4, p < .01. Figure 4 indicates that all subjects showed increases in body movement throughout the task and that the high signal frequency condition resulted in an overall reduction in level of body movement. In addition, Figure 4 indicates that learning-disability subjects were higher in body movement in both frequency conditions. The Duncan Multiple Range test indicated that the signi-
BodyMovementand Inattention
335
90 I,-z
High FrequencyControl
~ 80
High FrequencyLD 70
~owFrequencyControl
.=.
z
60
,ia
FrequencyLD
n
50
I
i
1
I
I
2 3 QUARTER
4
Fig. 3. Percentage of signals correctly identified during each quarter of the vigilance task.
lib /
.,is/""~-Low FrequencyLD
3
,imoo,O~ o~176176176176176
/
/ 2
/,~Low FrequencyControl
~/ " ~ H i ,0"g. . . .h. .
.0
Frequency,LD
o o/" ."~176
1
~ 0
I 1
I I I 2 3 QUARTER
I 4
Fig. 4. Body movement during each quarter of the vigilance task.
336
Rugel, Cheatam, and Mitchell
ficant groups by quarters interaction was due to the relatively greater increase in body moyement by learning-disability subjects during the last two quarters of the vigilance task.
Discussion of Experiment IV
Hypothesis 1 is supported by the finding that the high signal frequency conditions result in lower levels of body movement. It would appear that as one increases the number of meaningful stimuli for the subject to respond to, he will become less underaroused and less active. With fewer meaningful stimuli to respond to greater underarousal and body activity will occur. It is proposed that the following sequence of events take place in the vigilance task. As a result of habituation to task-relevant stimuli, extinction, and other factors mentioned by Stroh (1971), fewer observing responses occur and vigilance performance shows a decrement. With few additional external sources of stimulation available, underarousal takes place and stimulus-seeking behavior begins to occur. This is manifested in the observed increases in body movement. Once stimulus-seeking behaviors begin, they interfere still further with task-relevant observing responses, thus causing still further decrements in vigilance performance. Hypothesis 2 was not supported by Experiment IV. This hypothesis predicted that learning-disabled children would show attentional deficits that would result in greater body movement. Learning-disabled children did show greater body movement levels b u t i n the absence of an attentional deficit. That attentional deficits occur in learning-disabled children is clear from the literature and from Experiments I and II. The failure to find such a deficit in Experiment IV may be due to the atypical third-quarter recovery in vigilance performance in both the learning-disabled and control groups. However, since in Experiments III and IV body movement differences were found in the absence of attentional differences, little support is present for hypothesis 2, which proposes that the attentional deficit is a determinent of the hyperactivity of learning-disabled children. The absence of support for hypothesis 2, however, poses the problem of accounting for the relationship between attention and activity level. Low attention and high activity level frequently occur together in learning-disabled children. They were also related in the present experiments sihce attention went down during the task as body activity went up. One explanation is in terms of the effect of arousal level on both variables. Underarousal creates stimulus seeking, which is manifested in increased body activity. These stimulus-seeking behaviors also interfere with task-relevant activities such as vigilance performance thus contributing to vigilance decrements. Therefore, the frequent correlational relationship found between attention and body activity may be due to a third variable, arousal level, which has effects on both attention and body activity. An explanation is also required for the higher activity level of learning-disabled
Body Movement and Inattention
337
children. The view of the present authors is that learning-disabled children may come into the task with inherently lower arousal levels (Hunter, Johnson, & Keefe, 1972). In addition, they may habituate faster to task-relevant stimuli (Rugel & Rosenthal, 1974), which also contributes to their level of underarousal. Lower arousal levels are characteristic of other populations of deviant children such as children with conduct disorders. Quay (1977) argues that stimulus-seeking behavior may account for many of the deviant behaviors of these children. Thus chronic under-arousal may contribute to a variety of disorders of childhood.
REFERENCES
Anderson, Halcomb, & Doyle. The measurement of attentional deficits. Exceptional Children, 1973, 39(7), 534-538. Berlyne, D. E. Conflict, arousal and curiosity. New York: McGraw-Hill, 1960. Dykman, R. A., Ackerman, P. T., Ctements, S. D., & Peters, J. E. Specific learning disabilities: An attentional deficit syndrome. In H. Myklebust (Ed.), Progress in learning disabilities, New York: Grune & Stratton, 1971. Eiske, D. W., & Maddi, S. R. Functions of varied experience. Homewood, Illinois: Dorsey, 1961. Hunter, E. J., Johnson, L. C., & Keefe, F. B. Electrodermal and cardiovascular responses in nonreaders. Journal of Learning Disabilities, 1972, 5, 187-197. Pope, L. Motor activity in brain injured children. American Journal of Orthopsychiatry, 1970,40, 15. Quay, H. C. Psychopathic behavior: Reflections on its nature, origins and treatment. In F. Weizman & I. Uzgiris (Eds.), The StructuringofExperience, New York: Plenum, 1977. Rugel, R. P., & Rosenthal, R. Skin conductance, reaction time and observational ratings in learning disabled children. Journal of Abnormal Child Psychology, 1974, 2(3), 183-192. Schultz, D. P. Sensory restriction-effects on behavior. New York: Academic Press, 1965. Sroufe, L. A., Sonies, B. C., West, W. D., & Wright, F. S. Anticipatory heart rate deceleration and reaction time in children with and without referral for learning disability. Child Development, 1973, 44, 267-273. Stroh, C. M. Vigilance. The problem of sustained attention. New York: Pergamon Press, 1971. Zentall, S. Optimal stimulation as theoretical basis of hyperactivity. Ameriean Journal of Orthopsychiatry, 1975,45(4), 549-563.
