Journal of Abnormal Child Psychology, VoL 6, No. 3, 1978, pp. 407-412
Stimulus-Governance and the Hyperkinetic Syndrome 1 Max Lesnik-Oberstein: Bloemendaal Psychiatric Hospital, The Hague Harry van der Vlugt 3
University of Leiden
Eric Hoencamp 4 Bloemendaal Psychiatric Hospital, The Hague Dik Juffermans University of Leiden Leo Cohen Bloemendaal Psychiatric Hospital, The Hague
The hypothesis that hyperkinetic children are stimulus-governed was tested. In a sample o f 39 nonmedicated hyperkinetic boys 26 were found to be stimulusgoverned. In a control sample o f 20 nonmedicated boys 6 were found to be stimulus-governed. A n association was found between the hyperkinetic syndrome and stimulus-governance. The hypothesis is raised that response to methylphenidate is related to stimulus-governance. Several issues raised by the research are discussed. On the basis of her researches with kinesthetic figural aftereffects, Petrie (1967) described two main types of persons in terms of their characteristic perceptual style: augmenters and reducers. She also described an atypical perceptual style that she found only in patients (otherwise unspecified) with organic cerebral Manuscript received in final form April 3, 1978. This research was supported in part by a grant from Bloemendaal Psychiatric Hospital, The Hague, The Netherlands. The authors wish to thank Mr. E. M. Ockhorst, for constructing the KFA-testing equipment, and Mr. R. Reyneart, for helping with the computer analysis. An earlier draft of the paper was presented at the European Conference of Neuropsychology, sponsored by the InternationalNeuropsychology Society, at Oxford University, England. 2Address all correspondence to Dr. M. Lesnik-Oberstein, Child Psychiatry Department, Bloemendaal Psychiatric Hospital, Monsterseweg 93, The Hague, The Netherlands. Now at the University of Tilburg. "Now at St. Elisabeth Hospital, Curaqao. 407 0 0 9 1 - 0 6 2 7 / 7 8 / 0 9 0 0 - 0 4 0 7 5 0 5 . 0 0 / 0 9 1978 Plenum Publishing Corporation
408
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
damage, and in 15% of a sample of juvenile delinquents: stimulus-governance. An augmenter tends to increase the experienced magnitude of sensory input, while a reducer tends to decrease the experienced magnitude of sensory input. A stimulus-governed individual, unlike an augmenter or reducer, reduces the magnitude of a stimulus if the preceding stimulus is of greater magnitude, and augments the magnitude of a stimulus if the preceding stimulus is of smaller magnitude. Buchsbaum and Silverman (1968) found that augmenters and reducers have different visual average-evoked-response patterns, s They postulated the existence of a stimulus intensity control mechanism in the central nervous system. Researches have established a relation between augmentation and reduction and a variety of personality characteristics and psychopathological conditions (Buchsbaum, 1975; Buchsbaum & Pfefferbaum, 1971; Petrie, 1967; Silverman, 1972; Silverman, Buchsbaum, & Henkin, 1969). The present article reports a study designed to test the hypothesis of the first author that hyperkinetic children are stimulus-governed, in contrast to nonhyperkinetic children.
METHOD
Subjects The hyperkinetic sample consisted of 39 boys. They came from a Dutch special education primary school where, in the Netherlands, such children are often sent. They met the following selection criteria: (1) 7 to 13 years of age, (2) referral to the school for hyperkinesis, (3) minimum WISC full-scale IQ of 90, (4) no report of gross neurological impairment in their medical records, (5) not receiving medication, 6 and (6) a score in the upper 10th percentile range of children who score positive for the hyperkinetic syndrome on Safer and Allen's (1976) classroom teacher's behavior checklist. 7 The control sample was composed of 20 boys attending an ordinary Dutch primary school. They met the following selection criteria: (1) 8 to 11 years of age, (2) an IQ above 90, (3) not receiving medication, and (4) a score negative for the hyperkinetic syndrome on Safer and Allen's classroom teacher's behavior checklist. s Visual average-evoked-responsetechniques do not permit the detection of stimulus-governance. As a result, stimulus-governed subjects are incorrectly identified as augmenters or reducers. 6In the Netherlands hyperkinetic children are very rarely given medication. 7The checklist (which was translated into Dutch for the study) assesses pupil classroom behavior. The initial few items on the checklist are adapted from the ratings of Werry and Quay (1969); the remaining are adapted from the work of Connors (1969). A number of the items discriminate for the hyperkinetic syndrome.
Stimulus-Governance and Hyperkinesis
409
Procedure
The Kinesthetic Figural Aftereffects Test (KFA), developed by Petrie (1967), permits the quantitative determination of augmentation, reduction, and stimulus-governance. The KFA test is carried out in two testing sessions. In Petrie's procedure the two testing sessions are separated by an interval of at least 48 hours, and in each of the sessions the subject's hands are kept inactive for a period of 45 minutes prior to testing. We used a fixed interval of 48 hours between testing sessions and replaced the 45-minute period of manual inactivity with a 45-minute period of what we considered to be relatively standard stimulation. This period consisted of the administration of a series of psychological tests. The majority of the tests required verbal responses and the children were instructed not to use their hands during their administration. Some of the tests required use of the hands. The psychological tests were, in order of presentation: a bicycle and tree drawing task, a visual line-size judgment test (part 1), a digitspan test, a story-recall test (part 1), a picture-recall test (part 1), a visual linesize judgment test (part 2), a rhythm test, a picture-recall test (part 2), a storyrecall test (part 2), and the Bender Visual Motor Gestalt Test. Following the tests the subject was blindfolded. The thumb and index finger of his preferred hand were placed on a measuring block (3.81 cm wide in the first session and 5.08 cm wide in the second session). 8 The thumb and index finger of his nonpreferred hand were placed on a tapered graduated bar, and he was asked to indicate the place on the bar that felt just as wide as the measuring block. The subject carried out this procedure six times. The first two times were practice trials. The average of the last four measurements was the baseline measurement. The subject then was asked to rub for 90 seconds a stimulating block with the thumb and index finger of his preferred hand. In the first session the stimulating block was 6.35 cm wide and was wider than the measuring block; in the second session the stimulating block was 2.54 cm wide and was narrower than the measuring block. After having rubbed the stimulating block, the thumb and index finger of the subject's preferred hand were placed on the measuring block. With the thumb and index finger of his nonpreferred hand placed on the tapered graduated bar, the subject was asked again to locate where the bar felt as wide as the measuring block. The subject carried out this locating procedure four times. The stimulation-cure-four-measurements sequence was then repeated two times. (In the last sequence, the subject rubbed the stimulating block for 120 seconds instead of for 90 seconds.) The average of all 12 poststimulation measurements was the poststimulation measurement. The difference between
8For details on KFA materials and for an expanded discussion of procedure see Petrie (1967).
410
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
the poststimulation measurement and the baseline measurement was the subject's score for that session. At the end of the full procedure, involving two testing sessions 48 hours apart, two scores were obtained: a score for the session using the wide stimulating block, and a score for the session using the narrow stimulating block. We defined an augmenter as a subject with a positive score on both the wide and the narrow stimulating block sessions. He overestimates the size of the measuring block irrespective of the size of the stimulating block. A reducer was defined as a subject with a negative score on both the wide and the narrow stimulating block sessions. He understimates the size of the measuring block irrespective of the size of the stimulating block. A stimulus-governed subject was defined as one having a negative score, i.e., a reducer's score, on the wide stimulating block session, and a positive score, an augmenter's score, on the narrow stimulating block session. He underestimates the size of the measuring block if the size of the stimulating block is wider than that of the measuring block, and he overestimates the size of the measuring block if the size of the stimulating block is narrower than that of the measuring block.
RESULTS
The results of the KFA testing were as follows. Of the 39 hyperkinetic children tested, 26 were stimulus-governed. Of the 20 control children tested, 6 were stimulus-governed. This difference is significant (chi-square corrected for continuity = 5.76, df = 1, p = .008, one-tailed). The mean difference between the KFA scores for the wide and narrow stimulating block sessions was 107.6 mm (SD = 52.4 mm) for the hyperkinetic stimulus-governed group, 6.5 mm (SD = 61.6 ram) for the hyperkinetic non-stimulus-governed group, 23.3 mm (SD = 40.8 mm) for the control non-stimulus-governed group, and 80.3 mm (SD = 38.0) for the control stimulus-governed group. The results of the other tests are not presented.
DISCUSSION
Our results indicate that there is an association between stimulus-governance and the hyperkinetic syndrome. Approximately two-thirds ofhyperkinetic boys appear to be stimulus-governed. The way in which stimulus-governance is related to the symptoms of the hyperkinetic syndrome is not clear. We speculate that stimulus-governance, in some as yet not understood way, interferes with attention. The shifts between augmentation and reduction that occur in stimulusgovernance may result in a perceptual environment that interferes with atten-
Stimulus-Governance and Hyperkinesis
411
tional processes. We think that stimulus-governance may be the result of immaturity or selective fallout of inhibitory neurons in the CNS (Hebb, 1976). In at least one subclass of hyperkinetic children stimulus-governance is not present. The presence of stimulus-governance is therefore not a necessary condition for all types of the hyperkinetic syndrome. The fact that a number of our controls were stimulus-governed indicates that stimulus-governance is not a sufficient condition for hyperkinesis. If stimulus-governance plays a pathogenic role in the hyperkinetic syndrome it follows that the stimulus-governed controls are characterized by an absence of other pathogenic factors present in hyperkinetic children and/or by the presence of compensatory factors. The greater age range of the hyperkinetic sample (7 to 13 years vs. 8 to 11 years for the control sample) does not contribute to the association found between stimulus-governance and the hyperkinetic syndrome. When 7-, 12-, and 13-year-old hyperkinetic boys are excluded from the analysis, 17 of the 25 remaining hyperkinetic boys are stimulus-governed (chi-square corrected for continuity = 4.99, d f = 1, p = .013, one-tailed). Petrie (1967) found no stimulus-governance in a sample of nonclinical children. Six of our 20 controls were stimulus-governed. Two possible explanations appear to us to account for the difference in results. The difference may be due to a difference in samples. Petrie's sample appears to have been drawn mainly from academic families while our sample was fairly representative of a Dutch primary school population. The difference in results may also be due to the difference between Petrie's and our procedure in the 45 minutes preceding KFA testing. We hypothesize that methylphenidate diminishes the degree of stimulusgovernance in children or makes them into augmenters or reducers, and that these changes correlate with clinical improvement in hyperkinetic children. This fits well with the fact that the proportion of hyperkinetic children found to be stimulus-governed in our sample is close to the proportion ofhyperkinetic children found to respond favorably to methylphenidate (Barkley, 1976, 1977). It appears desirable to carry out further research in the above-mentioned areas.
REFERENCES Barkley, R. A. Predicting the response of hyperkinetic children to stimulant drugs: A review. Journal of Abnormal Child Psychology, 1976, 4, 327-348. Barkley, R. A. A review of stimulant drug research with hyperactive children. Journal of Child Psychology and Psychiatry, 1977, 18, 137-166. Buchsbaum, M. Average evoked response. Augmenting/reducingin schizophrenia and affectire disorders. In D. X. Freedman (Ed.), Biology of the ma/orpsychoses. New York: Raven Press, 1975. Buchsbaum, M., & Pfefferbaum T. IndividuaI differences in stimulus intensity response. Psychophysiology, 1971,8, 600-611.
412
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
Buchsbaum, M., & Silverman J. Stimulus intensity control and the cortical evoked response. Psychosomatic Medicine, 1968, 30, 12-22. Connors, C. K. A teacher rating scale for use in drug studies with children. American Journal of Psychiatry, 1969, 126, 884-888. Hebb, D. O. Physiological learning theory. Journal of Abnormal Child Psychology, 1976, 4, 309-314. Petrie, A. Individuality in pain and suffering. Chicago: University of Chicago Press, 1967. Safer, D. J., & Allen, R. Hyperactive children, diagnosis and management. Baltimore: University Park Press, 1976. Silverman, J. Stimulus intensity modulation and psychological dis-ease. PsychopharmacoIogia (Berlin) 1972, 24, 42-80. Silverman, J., Buchsbaum, M., & Henkin, R. Stimulus sensitivity and stimulus intensity control. Perceptual and Motor Skills. 1969, 28, 71-78. Werry, J. S., & Quay, H. C. Observing the classroom behavior of elementary school children. Exceptional Children, 1969, 35, 461-470.
Stimulus-Governance and the Hyperkinetic Syndrome 1 Max Lesnik-Oberstein: Bloemendaal Psychiatric Hospital, The Hague Harry van der Vlugt 3
University of Leiden
Eric Hoencamp 4 Bloemendaal Psychiatric Hospital, The Hague Dik Juffermans University of Leiden Leo Cohen Bloemendaal Psychiatric Hospital, The Hague
The hypothesis that hyperkinetic children are stimulus-governed was tested. In a sample o f 39 nonmedicated hyperkinetic boys 26 were found to be stimulusgoverned. In a control sample o f 20 nonmedicated boys 6 were found to be stimulus-governed. A n association was found between the hyperkinetic syndrome and stimulus-governance. The hypothesis is raised that response to methylphenidate is related to stimulus-governance. Several issues raised by the research are discussed. On the basis of her researches with kinesthetic figural aftereffects, Petrie (1967) described two main types of persons in terms of their characteristic perceptual style: augmenters and reducers. She also described an atypical perceptual style that she found only in patients (otherwise unspecified) with organic cerebral Manuscript received in final form April 3, 1978. This research was supported in part by a grant from Bloemendaal Psychiatric Hospital, The Hague, The Netherlands. The authors wish to thank Mr. E. M. Ockhorst, for constructing the KFA-testing equipment, and Mr. R. Reyneart, for helping with the computer analysis. An earlier draft of the paper was presented at the European Conference of Neuropsychology, sponsored by the InternationalNeuropsychology Society, at Oxford University, England. 2Address all correspondence to Dr. M. Lesnik-Oberstein, Child Psychiatry Department, Bloemendaal Psychiatric Hospital, Monsterseweg 93, The Hague, The Netherlands. Now at the University of Tilburg. "Now at St. Elisabeth Hospital, Curaqao. 407 0 0 9 1 - 0 6 2 7 / 7 8 / 0 9 0 0 - 0 4 0 7 5 0 5 . 0 0 / 0 9 1978 Plenum Publishing Corporation
408
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
damage, and in 15% of a sample of juvenile delinquents: stimulus-governance. An augmenter tends to increase the experienced magnitude of sensory input, while a reducer tends to decrease the experienced magnitude of sensory input. A stimulus-governed individual, unlike an augmenter or reducer, reduces the magnitude of a stimulus if the preceding stimulus is of greater magnitude, and augments the magnitude of a stimulus if the preceding stimulus is of smaller magnitude. Buchsbaum and Silverman (1968) found that augmenters and reducers have different visual average-evoked-response patterns, s They postulated the existence of a stimulus intensity control mechanism in the central nervous system. Researches have established a relation between augmentation and reduction and a variety of personality characteristics and psychopathological conditions (Buchsbaum, 1975; Buchsbaum & Pfefferbaum, 1971; Petrie, 1967; Silverman, 1972; Silverman, Buchsbaum, & Henkin, 1969). The present article reports a study designed to test the hypothesis of the first author that hyperkinetic children are stimulus-governed, in contrast to nonhyperkinetic children.
METHOD
Subjects The hyperkinetic sample consisted of 39 boys. They came from a Dutch special education primary school where, in the Netherlands, such children are often sent. They met the following selection criteria: (1) 7 to 13 years of age, (2) referral to the school for hyperkinesis, (3) minimum WISC full-scale IQ of 90, (4) no report of gross neurological impairment in their medical records, (5) not receiving medication, 6 and (6) a score in the upper 10th percentile range of children who score positive for the hyperkinetic syndrome on Safer and Allen's (1976) classroom teacher's behavior checklist. 7 The control sample was composed of 20 boys attending an ordinary Dutch primary school. They met the following selection criteria: (1) 8 to 11 years of age, (2) an IQ above 90, (3) not receiving medication, and (4) a score negative for the hyperkinetic syndrome on Safer and Allen's classroom teacher's behavior checklist. s Visual average-evoked-responsetechniques do not permit the detection of stimulus-governance. As a result, stimulus-governed subjects are incorrectly identified as augmenters or reducers. 6In the Netherlands hyperkinetic children are very rarely given medication. 7The checklist (which was translated into Dutch for the study) assesses pupil classroom behavior. The initial few items on the checklist are adapted from the ratings of Werry and Quay (1969); the remaining are adapted from the work of Connors (1969). A number of the items discriminate for the hyperkinetic syndrome.
Stimulus-Governance and Hyperkinesis
409
Procedure
The Kinesthetic Figural Aftereffects Test (KFA), developed by Petrie (1967), permits the quantitative determination of augmentation, reduction, and stimulus-governance. The KFA test is carried out in two testing sessions. In Petrie's procedure the two testing sessions are separated by an interval of at least 48 hours, and in each of the sessions the subject's hands are kept inactive for a period of 45 minutes prior to testing. We used a fixed interval of 48 hours between testing sessions and replaced the 45-minute period of manual inactivity with a 45-minute period of what we considered to be relatively standard stimulation. This period consisted of the administration of a series of psychological tests. The majority of the tests required verbal responses and the children were instructed not to use their hands during their administration. Some of the tests required use of the hands. The psychological tests were, in order of presentation: a bicycle and tree drawing task, a visual line-size judgment test (part 1), a digitspan test, a story-recall test (part 1), a picture-recall test (part 1), a visual linesize judgment test (part 2), a rhythm test, a picture-recall test (part 2), a storyrecall test (part 2), and the Bender Visual Motor Gestalt Test. Following the tests the subject was blindfolded. The thumb and index finger of his preferred hand were placed on a measuring block (3.81 cm wide in the first session and 5.08 cm wide in the second session). 8 The thumb and index finger of his nonpreferred hand were placed on a tapered graduated bar, and he was asked to indicate the place on the bar that felt just as wide as the measuring block. The subject carried out this procedure six times. The first two times were practice trials. The average of the last four measurements was the baseline measurement. The subject then was asked to rub for 90 seconds a stimulating block with the thumb and index finger of his preferred hand. In the first session the stimulating block was 6.35 cm wide and was wider than the measuring block; in the second session the stimulating block was 2.54 cm wide and was narrower than the measuring block. After having rubbed the stimulating block, the thumb and index finger of the subject's preferred hand were placed on the measuring block. With the thumb and index finger of his nonpreferred hand placed on the tapered graduated bar, the subject was asked again to locate where the bar felt as wide as the measuring block. The subject carried out this locating procedure four times. The stimulation-cure-four-measurements sequence was then repeated two times. (In the last sequence, the subject rubbed the stimulating block for 120 seconds instead of for 90 seconds.) The average of all 12 poststimulation measurements was the poststimulation measurement. The difference between
8For details on KFA materials and for an expanded discussion of procedure see Petrie (1967).
410
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
the poststimulation measurement and the baseline measurement was the subject's score for that session. At the end of the full procedure, involving two testing sessions 48 hours apart, two scores were obtained: a score for the session using the wide stimulating block, and a score for the session using the narrow stimulating block. We defined an augmenter as a subject with a positive score on both the wide and the narrow stimulating block sessions. He overestimates the size of the measuring block irrespective of the size of the stimulating block. A reducer was defined as a subject with a negative score on both the wide and the narrow stimulating block sessions. He understimates the size of the measuring block irrespective of the size of the stimulating block. A stimulus-governed subject was defined as one having a negative score, i.e., a reducer's score, on the wide stimulating block session, and a positive score, an augmenter's score, on the narrow stimulating block session. He underestimates the size of the measuring block if the size of the stimulating block is wider than that of the measuring block, and he overestimates the size of the measuring block if the size of the stimulating block is narrower than that of the measuring block.
RESULTS
The results of the KFA testing were as follows. Of the 39 hyperkinetic children tested, 26 were stimulus-governed. Of the 20 control children tested, 6 were stimulus-governed. This difference is significant (chi-square corrected for continuity = 5.76, df = 1, p = .008, one-tailed). The mean difference between the KFA scores for the wide and narrow stimulating block sessions was 107.6 mm (SD = 52.4 mm) for the hyperkinetic stimulus-governed group, 6.5 mm (SD = 61.6 ram) for the hyperkinetic non-stimulus-governed group, 23.3 mm (SD = 40.8 mm) for the control non-stimulus-governed group, and 80.3 mm (SD = 38.0) for the control stimulus-governed group. The results of the other tests are not presented.
DISCUSSION
Our results indicate that there is an association between stimulus-governance and the hyperkinetic syndrome. Approximately two-thirds ofhyperkinetic boys appear to be stimulus-governed. The way in which stimulus-governance is related to the symptoms of the hyperkinetic syndrome is not clear. We speculate that stimulus-governance, in some as yet not understood way, interferes with attention. The shifts between augmentation and reduction that occur in stimulusgovernance may result in a perceptual environment that interferes with atten-
Stimulus-Governance and Hyperkinesis
411
tional processes. We think that stimulus-governance may be the result of immaturity or selective fallout of inhibitory neurons in the CNS (Hebb, 1976). In at least one subclass of hyperkinetic children stimulus-governance is not present. The presence of stimulus-governance is therefore not a necessary condition for all types of the hyperkinetic syndrome. The fact that a number of our controls were stimulus-governed indicates that stimulus-governance is not a sufficient condition for hyperkinesis. If stimulus-governance plays a pathogenic role in the hyperkinetic syndrome it follows that the stimulus-governed controls are characterized by an absence of other pathogenic factors present in hyperkinetic children and/or by the presence of compensatory factors. The greater age range of the hyperkinetic sample (7 to 13 years vs. 8 to 11 years for the control sample) does not contribute to the association found between stimulus-governance and the hyperkinetic syndrome. When 7-, 12-, and 13-year-old hyperkinetic boys are excluded from the analysis, 17 of the 25 remaining hyperkinetic boys are stimulus-governed (chi-square corrected for continuity = 4.99, d f = 1, p = .013, one-tailed). Petrie (1967) found no stimulus-governance in a sample of nonclinical children. Six of our 20 controls were stimulus-governed. Two possible explanations appear to us to account for the difference in results. The difference may be due to a difference in samples. Petrie's sample appears to have been drawn mainly from academic families while our sample was fairly representative of a Dutch primary school population. The difference in results may also be due to the difference between Petrie's and our procedure in the 45 minutes preceding KFA testing. We hypothesize that methylphenidate diminishes the degree of stimulusgovernance in children or makes them into augmenters or reducers, and that these changes correlate with clinical improvement in hyperkinetic children. This fits well with the fact that the proportion of hyperkinetic children found to be stimulus-governed in our sample is close to the proportion ofhyperkinetic children found to respond favorably to methylphenidate (Barkley, 1976, 1977). It appears desirable to carry out further research in the above-mentioned areas.
REFERENCES Barkley, R. A. Predicting the response of hyperkinetic children to stimulant drugs: A review. Journal of Abnormal Child Psychology, 1976, 4, 327-348. Barkley, R. A. A review of stimulant drug research with hyperactive children. Journal of Child Psychology and Psychiatry, 1977, 18, 137-166. Buchsbaum, M. Average evoked response. Augmenting/reducingin schizophrenia and affectire disorders. In D. X. Freedman (Ed.), Biology of the ma/orpsychoses. New York: Raven Press, 1975. Buchsbaum, M., & Pfefferbaum T. IndividuaI differences in stimulus intensity response. Psychophysiology, 1971,8, 600-611.
412
Lesnik-Oberstein, van der Vlugt, Hoencamp, Juffermans, and Cohen
Buchsbaum, M., & Silverman J. Stimulus intensity control and the cortical evoked response. Psychosomatic Medicine, 1968, 30, 12-22. Connors, C. K. A teacher rating scale for use in drug studies with children. American Journal of Psychiatry, 1969, 126, 884-888. Hebb, D. O. Physiological learning theory. Journal of Abnormal Child Psychology, 1976, 4, 309-314. Petrie, A. Individuality in pain and suffering. Chicago: University of Chicago Press, 1967. Safer, D. J., & Allen, R. Hyperactive children, diagnosis and management. Baltimore: University Park Press, 1976. Silverman, J. Stimulus intensity modulation and psychological dis-ease. PsychopharmacoIogia (Berlin) 1972, 24, 42-80. Silverman, J., Buchsbaum, M., & Henkin, R. Stimulus sensitivity and stimulus intensity control. Perceptual and Motor Skills. 1969, 28, 71-78. Werry, J. S., & Quay, H. C. Observing the classroom behavior of elementary school children. Exceptional Children, 1969, 35, 461-470.
