3~?
DIFFERENTIAL EFFECTS OF BIOFEEDBACK INPUT
ON LOWERING FRONTALIS ELECTROMYOGRAPHIC
LEVELS IN RIGHT AND LEFT HANDERS
DISSERTATION
Presented to the Graduate Council of the
University of North Texas in Partial
Fulfillment of the Requirements
For the Degree of
DOCTOR OF PHILOSOPHY
By
Kenneth N. Walker, B.S., M.Ed,
Denton, Texas
August, 1990 Walker, Kenneth N. Differential Effects of Biofeedback
Input on Lowering Frontalis Electromyographic Levels In
Right and Left Handers. Doctor of Philosophy (Health
Psychology/Behavioral Medicine), August 1990, 70 pages, 3 tables, 6 figures, references, 73 titles.
This investigation was an attempt to replicate and expand previous research which suggested that laterality of electromyographic biofeedback input had a significant effect in lowering frontalis muscle activity. In 1984 Ginn and
Harrell conducted a study in which they reported that
subjects receiving left ear only audio biofeedback had
significantly greater reductions in frontalis muscle
activity than those receiving right ear only or both ear
feedback. This study was limited to one biofeedback session
and subjects were selected based on demonstration of right
hand/ear dominance. The purpose of the present study was to
determine whether the left ear effect reported by Ginn and
Harrell could be replicated. Furthermore, the current
investigation sought to extend the previous finding to left
handed subjects and explore the stability of the effect, if
found, by adding a second biofeedback session.
Subjects were 96 students recruited from undergraduate
psychology classes. They were screened for handedness by
the Edinburgh Handedness Inventory which resulted in identification of 48 right handers and 48 left handers.
Subjects were randomly assigned to one of four groups
consisting of left ear feedback, right ear feedback, both
ears feedback, and controls. This resulted in eight
conditions.
Analysis of variance of microvolt changes from baseline
found no statistically significant differences between groups. An examination of the rank order of the data reveal a left ear group performance in the same direction as those reported by Ginn and Harrell (1984). TABLE OF CONTENTS
Page
LIST OF TABLES iv
LIST OF ILLUSTRATIONS V
DIFFERENTIAL EFFECTS OF BIOFEEDBACK INPUT ON LOWERING
FRONTALIS ELECTROMYOGRAPHIC LEVELS IN RIGHT AND LEFT HANDERS
Introduction 1
Method 17
Subjects Apparatus and Materials Procedures Results 22
Discussion 31
APPENDIX 37
REFERENCES 61
ill LIST OF TABLES
Table Page
1. Handprefrence by Group by Time Analysis of Variance of Microvolt Change Scores Summary 25
2. Group by Time Analysis of Variance of Microvolt Change Scores Summary 30
3. Edinbourgh Inventory and Dichotic Words Correlations 31
IV LIST OF ILLUSTRATIONS
Figure Page
1. Group by Time by Handedness Across Session (raw scores) 23
2. Group by Time by Handedness Across Sessions (difference scores) 24
3. Left Handers Group by Time Across Sessions (raw scores) 26
4. Left Handers Group by Time Across Sessions (difference scores) 27
5. Right Handers Group by Time Across Sessions (raw scores) 28
6. Right Handers Group by Time Across Sessions (difference scores) 29 DIFFERENTIAL EFFECTS OF BIOFEEDBACK INPUT
ON LOWERING FRONTALIS ELECTROMYOGRAPHIC
LEVELS IN RIGHT AND LEFT HANDERS
A considerable amount of research has been generated to
suggest that the two cerebral hemispheres differ in
function. Recently, it has been suggested that
lateralization of brain functions may be responsible for
enhancing or impeding relaxation, depending upon the
hemisphere accessed during biofeedback (Greemstadt, Schuman
& Shapiro, 1979; Ginn & Harrell, 1984; Watson, 1990).
Differences in hemispheric specialization of right and left
handers has also been noted in a number of studies (Nagae,
1985; McGlone, 1980; Beaton, 1986).
Cerebral Asymmetry
Differences in function and structure of the two
cerebral hemispheres has long been noted in the literature
(Cunningham, 1882). Evidence of anatomical differences
between the left and right sides of the brain was offered by
Geschwind and Levitsky (1968). By examining the upper
surface of the temporal lobe, they found the planum
temporale to be larger on the left side in 65% of the cases.
LeMay (1976) investigated anatomical asymmetries using computerized axial tomography (CAT scan). Results of this analysis revealed the anterior area of the right hemisphere to be wider than the left in 70% of those examined.
Witelson (1983) found a correlation between a larger left planum temporale and left hemisphere dominance, as demonstrated by dichotic listening, hand preference and
finger tapping task. More recently, Kertesz, Black, Polk and Howell (1986) used magnetic resonance imaging (MRI) to explore asymmetries. MRI revealed differences in the sulcal demarcation of the posterior operculum from the parietal cortex that correlate with handedness in normal subjects.
They noted that the sulcal demarcation is greater on the right in most right handers, but evenly distributed in left handers. A regional cerebral blood flow technique has
suggested that right handers have higher concentrations of grey matter, in the left hemisphere than in the right,
relative to white matter (Gur, Packer, Hungerbuhler,
Reivich, Obrist, Amarne & Sackeim, 1980).
Functional brain asymmetry refers to the difference between left hemisphere and right hemisphere functions.
Although researchers typically agree that this is not
absolute, but a matter of degree (Beaton, 1986). There are
a number of dichotomies suggested from the literature. The most frequently referred to and unequivocal is that of verbal versus non-verbal. One of the first published
accounts of this was Broca's discovery, on post mortem examination, that a patient who had been aphasic had severe
damage to a certain area in the left hemisphere (Spreinger &
Deutsch, 1974). This difference has further been
established in patients treated by left hemispherectomy for malignant tumor (Beaton, 1986). Damasio, Almeida and
Damasio, (1975) noted that aphasic symptoms are only rarely
seen in patients with right hemisphere lesions or total
Fight hemispherectomy. Searleman (1977) has suggested that
left hemisphere verbal dominance may be limited to speech production and not comprehension. However, the right hemisphere appears to also be involved in verbal function.
Ross (1981) reported that right hemisphere damage can interfere with both production and reception of prosody in speech.
In music, it has been suggested that the left hemisphere is specialized for perceptual processing of linguistic information such as rhythm, temporal order, duration, simultaneity, and articulation. The right hemisphere is thought to control perceptual processes such a loudness, harmony, intonation, timbre, resonance, and pitch
(Bradshaw & Nettleton, 1983; Gordon, 1983). Carmon, Lavy,
Gordon, and Portnoy (1975) found increased regional cerebral blood flow to the right hemisphere when subjects listen to instrumental music and decreased flow in the same are when listening to passages of prose. Using a dichotic listening task Peretz and Morais (1980) found that subjects who
focused on analytic strategies in listening to music tended
to show a left hemisphere advantage. Right hemisphere
superior subjects relied more on a holistic analysis.
O Boyle and Sanford (1988) conducted two experiments
investigating cerebral asymmetry in music. They concluded
that right hemisphere functions typically reported for the
processing of musical stimuli is primarily related to pitch and intonation.
Hemispheric specialization has also been suggested in
perceptual, spatial, and analytic functions. Weisenberg and
McBride (1935) first noted that damage to the right
hemisphere typically resulted in poor performance on
nonverbal task involving the manipulation of geometric
figures, puzzle assembly, completion of missing parts of
patterns and figures, and other task involving form,
distance, and space relationships. These patients
additionally often had profound disturbances in orientation,
becoming disoriented even in familiar surrounding. Levy
(1974) concluded that the left hemisphere was superior in
analytic information processing strategies while the right
hemisphere seems to process information in a holistic fashion.
Another distinction in left-right functions have been the apparent differences in impairment to damage to the two hemispheres. Semmes (1968) observed that relatively little left hemisphere damage results in loss of specific functions while much greater damage is required to disturb right hemisphere functions.
Laterality of function has also been reported in the
study of emotion. Goldstein (1939) reported observations in which patients with left hemisphere damage frequently
experienced volatile emotional reactions while right
hemisphere damage was observed to result in an indifferent
attitude by the patient. It has further been claimed that
emotional stimuli, whether positive or negative, are more
accurately perceived by the right hemisphere (Beaton, 1986;
Bryden, Ley, & Sugerman, 1982) . Studies with split-brain
subjects have tended to support this view with more
emotional responses evoked when significant stimuli were
presented to the right hemisphere (Sperry, Zaidel & Zaidel,
1979). Suberi and McKeever (1977) found that there was a
left field-right hemisphere superiority in reaction time for
subjects to make facial discriminations when the faces
expressed emotions. Ley and Bryden (1982) have also claimed
that emotions are displayed more prominently on the left
side of the face. More recently, these assumptions have
been questioned. Braun, Baribeau, Ethier, Guerette, and
Proulx (1988) concluded from their research that cerebral dominance of facial expression appears to be more complex
than a simple right hemisphere dominance.
In other areas of emotional asymmetry, Ahern and
Schwartz (1979) addressed the idea that right hemisphere
superiority is for negative emotions while the left hemisphere is more involved in positive emotions. By using
eye movement to judge hemispheric activation, they found that questions related to positive emotions evoked movements suggestive of relative left hemisphere involvement.
Negative emotion questions activated movement suggestive of right hemisphere involvement. Higher levels of right hemisphere activation have also been reported during stress
(Tuker, Roth, Arneson & Buckingham, 1977). A final interpretation has been proposed by Ekman, Hager and Friesen
(1981). Citing neurological findings they have suggested that differences in left-right functions are related to spontaneous and deliberate expression of emotions. They reported that deliberate expression was associated with right hemisphere dominance and spontaneous expression was related to the left hemisphere.
Handedness
The relationship of hand dominance to hemispheric asymmetry of function has been an area of considerable interest. As noted by Beaton (1986) on hemisphere is connected primarily to the opposite side of the body. Related to this, researchers have described differences in
brain organization in left and right handers (Levy, 1969;
Levy & Reid, 1978).
The literature investigating these differences has been
considerable. Left handers have been found to be less
laterally differentiated than are right handers.
Specialization of language appears more lateralized to the
left hemisphere in right handers than left handers (Nagae,
1985). it has been suggested that verbal functions in left
handers are shared by both hemispheres resulting in more
right hemisphere language for left handers.
In studies of normal subjects, left handers have
demonstrated more reversed and bilateral representation for
nonverbal stimuli. This has been noted in stimuli presented tactually, visually, and audibly (Curry, 1973; Gilbert &
Bakan, 1973; Varney & Benton, 1975). McKeever (1986) investigated language laterality, spatial ability and verbal ability of 225 right handers and 134 left handers. His results indicated that right handers were significantly more lateralized on a language laterality task and were superior to left handers on a spatial visualization task. Left handers obtained higher scores on a vocabulary task.
In studies with brain-damaged subjects, left handers with right hemisphere lesion have shown deficits in language functions with little disturbance in visual-spatial processing, melody, construction ability and concentration
or attention (Delis, Simpson, & Knight, 1982). Borod,
Carper, Naeser, and Goodglass (1985) examined the
performance of 21 left handed and 57 right handed aphasics
with left hemisphere lesions. Left handers were
significantly more impaired on tasks involving visual-
spatial organization and construction. They concluded that
left handed aphasics have more left hemisphere
representation than right handers on tasks for which the
right hemisphere typically is dominant. They also noted
that only one percent of right handers observed with right
hemisphere lesions were aphasic, while twenty-four percent
of left handers with similar lesions were aphasic.
In attempting to explain the handness phenomena, Bakan
(1978) argued that whenever stressful events affect the left
hemisphere the right body side functions may be impaired
thus preference may shift from the right body side to the
left. As support for his "Birth Stress Hypothesis" he has
reviewed the higher than normal incidence of birth
complications and left hand preference in twins, stutterers,
dyslexics, mental-retardates, epileptics, alcoholics,
delinquents, and psychopaths (Bakan, 1971; 1975). In one
study Bakan (1975) examined 510 students with right and
left-hand preferences who reported complications experienced
by their mothers during their birth. Significantly more left handers (40%) than right handers (22%) reported stressful birth events which included multiple births, premature births, prolonged labor, caesarian births, and breathing difficulty. However, others using the methodology have failed to replicate these findings (Searleman, 1977).
Nachshon and Denno (1987) report that there is little evidence that birth stress is associated with left handedness. In their study of 987 boys and girls they found that there was no substantial link between birth stress and left-sided preferences.
In contrast to the Birth Stress Hypothesis, Levy and
Nagylaki (1972) have suggested a genetic theory of handedness. They propose the involvement of two genes. One coded for language representation on the left or right hemisphere and the other coded to determine hand preference, contralateral or ipsilateral, relative to language (1978).
Annett proposes that the variation observed in handedness is due to chance and the bias is produced by a genetic factor accentuated by cultural influences. Socio-Cultural factors have further been proposed by Leiber and Axelrod (1981).
They investigated family learning of handedness among 2257 subjects and found an increased incidence of left preference among individuals with left handed relatives. Hicks and
Kinsbourne (1976) studied adopted children and found a 10
significant relationship between biological parent and
child but not with adoptive parent.
Sex Differences
One of the first to record differences between the
sexes in brain functions was Lansdell (1961). He observed
that damage to one hemisphere had different consequences for
males and females. He further noted that females did not
show the predicted deficit, when part of the temporal lobe
was removed, as often as males. McGlone (1978) found that
male patients showed a lateralized response to brain damage,
such that left hemisphere lesions impaired verbal IQ
relative to performance IQ and right hemisphere lesions
impaired performance IQ relative to verbal IQ. Females did not show this same pattern. Unilateral damage to either side in females does not appear to impair verbal and performance IQ selectively, but lowers both in an equal manner. In an earlier study McGlone (1977) studied aphasic patients with left hemisphere damage and found that of 29 males, 14 were aphasic. Only two out of sixteen females were aphasic.
In normal subjects, studies have found sex differences in ear advantage using verbal dichotic listening task
(Remington, Krashen, & Harshman, 1974). These findings have typically been that males show a significant superiority of right ear advantage. Studies have also suggested a 11
nonverbal right ear advantage for males although Piazza
(1980) found that females exhibited significant ear
asymmetry to environmental sounds while males did not.
Visual field asymmetry has also been shown to be greater in
males for verbal material (Levy & Reid, 1976). Levy and
Reid (1978) have suggested that the right hemisphere is less
well organized for it's specialized functions in females
than in males. It has also been proposed that females
display a cognitive orientation similar to left handers with
bilateral language representation (Harris, 1978) . In
examining the literature pertaining to sex differences and
handedness, it has been noted that a higher incidence of
left handedness exists among males than females (Loo &
Schneider, 1979). Several explanations have been offered
for this. Taylor (1969) has argued that higher incidence of
male left handers can be explained based on the notion of
pathological left handedness. Annett (1979) has suggested
that females have a genetic bias to right handedness more so
than males.
Contrary to the prevailing view, Buffery and Gray
(1972) have argued that females are lateralized to a higher
degree than males for both verbal and spatial skills. They
have suggested that lateralized verbal abilities result in
superior verbal skills while lateralized spatial skills
result in deficits due to the type of skill and needed 12
integration on the hemispheres. This explains the observed superior verbal skills in females and spatial skills in males. Levy (1976) has suggested that spatial and verbal
abilities are related to language lateralization. She
proposes that expansion of language processing into the
right hemisphere results in enhanced verbal skills, but
reduced spatial ability for both females and left handers.
Studies reporting a sex difference in spatial ability, with
male superiority is well documented (McKeever, 1986).
Maccoby and Jacklin (1974) have noted an egually well
documented superiority for verbal abilities of females.
Biofeedback and Cerebral Laterality
Biofeedback utilizes the idea that behavioral feedback
leads to corrective responses. Using this principle, it has
been applied to a variety of physiological processes, many
of which have been previously thought to be involuntarily
controlled and therefore not capable of conscious
manipulation (Gatchel & Price, 1979).
The clinical populations who have used biofeedback have
varied in direct relationship to the physiological process
addressed. These have included: electroencephalographic
feedback in the treatment of epileptics (Lubar & Bahler,
1976); electromyographic feedback in the treatment of
bruxism (Schwartz, 1987); photoplethysmographic blood volume
feedback and thermal feedback in Reynaud's disease 13
(Blanchard & Haynes, 1975); rectal muscle feedback for the treatment of fecal incontinence (Schwartz, 1987); urine alarm feedback in the treatment of nocturnal enuresis
(Schwartz, 1987); blood pressure in hypertension (Benson,
Shapiro, Turskey, & Schwartz, 1971); heart rate feedback for premature ventricular contractions (Weiss & Engel, 1971); integrated electromographic feedback in disabled neurological patients and neuromuscular re-education of patients (Brundy, 1982; Schwartz, 1987); frontalis electromographic feedback in tension headaches (Haynes,
Griffin, Mooney, & Parise 1975); and peripheral vasodilation feedback in migraine headaches (Sargent, Green, & Walters,
1973) .
Several researchers have investigated the notion that biofeedback may be effected by brain lateralization. Using right handed subjects, Greenstadt, Schuman, and Chapiro
(1978) gave heart rate feedback in the form of a click which was presented to the subjects each time the interval between beats was shorter than a criterion. Subjects were divided into two groups. In one group feedback was limited to the left ear, while in the other it was presented only to the right ear. The researchers had hypothesized that heart rate biofeedback would be associated with left ear and right hemisphere involvement. However, the right ear, left hemisphere condition demonstrated a significant superiority 14
in increasing the heart rate. The authors reported a larger magnitude of change than noted in any other feedback format.
Sutter (1980) attempted to have subjects raise finger temperature while receiving right ear-right right finger, right ear-left finger, left ear-right finger, and left ear- left finger biofeedback. Feedback was given in the form of a tone and subjects also attempted to lower finger temperature under the same conditions. No hand or ear effects were found for finger temperature changes.
Studying hemispheric lateralization, Sussman and
Westbury (1978) reported on a number of studies using a dichotic monitoring task that functions both as a dichotic listening task and biofeedback task. The typical procedure used involved presenting a target tone to one ear and a cursor tone to the other. The objective was to match the target tone with the cursor tone which could be controlled by lateral tongue or hand movements. Sussman concluded that the matching of ongoing motor activity to a standard is primarily a left hemisphere function.
In a more recent study Ginn and Harrell (1984) attempted to evaluate the differential effects of electromographic (EMG) feedback to the right ear, left ear, and both ears while subjects attempted to lower activity of the frontalis muscle. Only right handed subjects who demonstrated lateralization on both the Edinburgh Handedness 15
Inventor (Oldfield, 1971) and the Dichotic Listening Task for Words (Kimura, 1967) were used in the study. Tonal biofeedback was used and controlled through the use of headphones and subjects received only one session.
Results of Ginn and Harrell's (1984) study suggest that there is a differential effect of left versus right versus both ears input in producing a reduction in forehead muscle tension levels. More specifically, he noted that left ear feedback was superior to all other feedback, while both ears feedback was superior to right ear input. This suggests that lateralized input can have a significant effect on learning a behaviorally complicated task. Four possible explanations for these findings were given.
The first of these explanations is that the differential ear effects are the result of which hemisphere receives the majority of the initial input. A second explanation offered by Ginn and Harrell (1984) is that one hemisphere may be more efficient in processing the biofeedback signals. A third explanation is that one hemisphere may regulate output to the frontalis muscles in a preferential manner. The fourth explanation offered is that some combination of the above three interact to achieve the result.
Speculating further, Ginn and Harrell (1984) suggests that his results may be due to a more active involvement of 16
the left hemisphere in relaxation than the right hemisphere.
According to his explanation input to the left hemisphere may interfere with attempts at relaxation. Therefore, right hemisphere input simply interferes the least, allowing the left hemisphere to function more efficiently.
Ginn and Harrell's (1984) research made several improvements over the two previous studies on differential ear input during biofeedback. Sutter (1980) and Greenstadt et al. (1978) both used self-report of handedness as their only measure of laterality. Ginn and Harrell attempted a more stringent criteria for laterality by including both the
Edinburgh Handedness Inventory and a dichotic listening task as a manner of screening subjects. Also Ginn and Harrell suggests that both previous studies attempted to influence autonomic nervous system behaviors whereas the frontalis is mediated by the central nervous system.
The purpose of this study was to investigate the differential effects of EMG biofeedback to the right ear, left ear, and both ears while trying to reduce frontalis muscle activity. Handedness differences were also investigated relative to biofeedback input. It was hypothesized that the right handed, left ear biofeedback group would result with significantly lower frontalis microvolt readings than all other groups. 17
Method
Subjects
The subjects were 96 students from undergraduate
psychology classes at the University of North Texas. To be
included in the study all subjects had to score a Laterality
Quotient of 68 (Decile = right 3) or greater or -54 (Decile
= Left 3) or less as measured by the Edinburgh Handedness
Inventory (Oldfield, 1971). There were 48 right handers and
48 left handers. Subjects ranged in age from 17 to 46. A
total of 151 individuals were screened to get the 96 who
completed the study (43 males and 53 females). Informed
consent was obtained prior to any participation (see
Appendix A).
Design
The Edinburgh Handedness Inventory (see Appendix B) was
initially administered and all subjects scoring within the criteria for left or right dominance were randomly assigned to one of four treatment conditions (left ear, right ear, both ears, and control). This resulted in eight groups consisting of twelve subjects each. Subjects were then administered the Dichotic Words task. Following this the procedure and apparatus were explained and the data was collected. A2x4x2xl2 factorial design (handedness x biofeedback input x session x time) resulted. 18
All combinations of the handedness factors was paired
with the four biofeedback conditions. These conditions were
EMG biofeedback to the left ear only; to the right ear only;
to both ears; and a control group monitored by EMG but not
given feedback. All biofeedback groups received veridical
EMG feedback in the form of a tone. This was provided by
stereo headphones capable of sending signals to the left ear
only, right ear only, or to both ears. Headphones were also
in place for the control group while data was collected
although no feedback was provided.
All groups received a five minute baseline period. EMG
levels were recorded at 100 second intervals for the five
minute baseline period and the 20 minute trial that
followed.
Apparatus and Materials
Stereo Equipment. Realistic Nova-Pro stereo headphones were used for both the right and left ear biofeedback
conditions. These headphones had individual ear volume adjustments that allowed the signal to go only to the ear of choice. Realistic Nova-10 stereo headphones were utilized for the both ear biofeedback and control conditions in addition to the dichotic word task. The Dichotic Words tape was presented through the earphones by a Sanyo RD7 two- channel stereo cassette player. 19
Biofeedback Equipment. A Colbourn S15-05 programmable electromyographic module was utilized to provide continuous tracking of microvolt levels in the forehead muscles of all subjects. Biofeedback groups were provided by a tone which varied in pitch based on the level of muscle activity. The control groups were not given access to the tone, however,
EMG activity was recorded. A Colbourn R21-16 printer furnished a printed record of EMG activity for all groups.
Microvolt levels were averaged and recorded every 100 seconds.
Dichotic Words. The Dichotic Words tape was administered from a cassette obtained from DK Consultant,
London, Ontario, Canada. The tape consisted of a series of paired words and has been prepared in such a manner that a different word is simultaneously presented to each ear.
There were 10 trials, with each consisting of four word- pairs presented in succession (see Appendix C). After each trial, the subject repeated the words heard. At the
completion of the 10 trials, the earphones were reversed and
the list was repeated. The number of correctly repeated words was recorded for each ear. The means and standard
deviations for the Dichotic Words task may be found in
Appendix D.
Edinburgh Handedness Inventory. This is a 12 item
instrument which assesses an individual degree of hand, eye, 20
and leg preference (see Appendix B). The Inventory has been found to be a very reliable quantitative measure of handedness (McFarland & Anderson, 1980). The Inventory produces a Laterality Quotient by subtracting the sum of the left preferences from the sum of the right and dividing this remainder by the sum of the right and left preferences.
This is then multiplied by 100 to arrive at the Laterality
Quotient. A positive Laterality Quotient indicates a right preference while left preferences result in a negative
Laterality Quotient.
Procedure
The Edinburgh Handedness Inventory was administered and those achieving the criteria were then given the Dichotic
Listening Task for Words. Random assignment was then made to one of four conditions resulting in a total of eight groups.
During the experimental stage, the subject was placed in a quiet room and seated in a comfortable chair. Each subject was informed as to which ear condition he would receive the biofeedback tone. After the apparatus had been explained, the forehead was prepared with a alcohol prep and three silver/silver chloride electrodes were placed one inch from either side of the reference electrode which was placed midway between the hairline and eyebrows above the bridge of the nose. The electrodes were checked by a volt ohmmeter to 21
insure that there was no impedance above 20,000 ohms between any two electrodes and that the impedance between any pair of electrodes did not differ by more than 10,000 ohms.
The volume to the feedback tone was adjusted prior to baseline measurements. During the baseline period subjects in all groups were asked to sit quietly. After the five minute baseline period the feedback tone was initiated for the feedback groups and the session started. Headphones were in place during baseline measures and throughout the session for all groups. Frontalis muscle activity was averaged over 100 second periods and printed out on a printer. This resulted in three measurements taken every five minutes for the 25 minute period creating 15 measurements in each of the two sessions. The first three recordings in each session were baseline measures.
Biofeedback Groups. Following the baseline period subjects were told that they would hear a tone which indicates the degree of tenseness of their forehead muscles.
They were instructed to use the tone to try to relax as much as possible. For specific instructions see Appendix E.
Control Groups. Following the baseline period the control subjects were asked to try to relax as much as possible the best way they could. Electrode attachments, 22
recordings and headphones placement were in the same manner as the biofeedback groups (see Appendix E).
Results
A four-way group(4) by session(2) by time(12) by hand preference(2) analysis of variance (ANOVA) was performed to examine the difference scores obtained by subtracting the baseline microvolt levels from the microvolt levels at each measurement interval under experimental and control conditions. Group refers to the four experimental conditions (right ear, left ear, both ears, and controls).
Session refers to the two sessions at which frontalis microvolt recordings were made. Time refers to the intervals within each session at which microvolt levels were recorded following baseline measurements (100 second intervals for 20 minutes resulting in 12 measurements).
Hand preference refers to the handedness of the subject
(right or left). The ANOVA reveals a significant main effect for time, F(ll, 968) = 10.49, p < .01 and a significant group by time by hand preference interaction,
F(33,968) = 1.5, p < .05. The ANOVA summary table data are presented in Table 1. Figure 1 represents the raw scores
for all groups across time intervals, with sessions one and
two pooled, for both left and right handed subjects. Figure
2 represents the means for the microvolt changes from
baseline on the same data. 23
FIGURE 1
GROUP BY TIME BY HANDEDNESS ACROSS SESSIONS (RAW SCORES)
6.25
LH/LE
LH/BE
LH/RE
LH/C
RH/BE RH/RE
3 4 5 6 7 9 10 11 12 13 14 15 TIME 1 10 ' 15 20 ' 25 ' 24
FIGURE 2
GROUP BY TIME BY HANDEDNESS ACROSS SESSIONS (DIFFERENCE SCORES)
LH/LE
M -0.25 LH/BE LH/RE LH/C
RH/LE
RH/BE RH/RE
S -1.25
-1.75 25
Table 1 Handprefrence bv Group by Time Analysis of Variance of Microvolt Change Scores Summary
finnrne nf Variation Sum of Souare df Mean Sauare F
Within Cells 1709.73 968 1.77
Time 203.76 11 18.52 10.49
Handprefrence by Time 20.41 11 1.86 1.05
Group by Time 73.14 33 2.22 1.25
Handprefrence by Group by time 87.72 33 2.66 1.50*
*E < .05
Following the significant interaction, two two-way analyses of variance (one for each level of handedness) on the difference scores at each interval were computed. The
ANOVA results revealed a significant main effect for Time for the left hand preference group F(23,1012) p < 05. The summary data are presented in Table 2. Figure 3 represents the means for microvolt changes for left handed subjects
across sessions. Figure 4 represents the raw scores on the
same data. No other statistically significant findings were
observed. The raw scores and difference scores for the
right handed group are graphed in figures 5 and 6.
Summary data on the non-significant ANOVA results can be
found in Appendix F. 26
FIGURE 3
LEFT HANDERS GROUP BY TIME ACROSS SESSIONS (RAW SCORES)
LEFT HAND/LEFT EAR
LEFT HAND/BOTH EARS
LEFT HAND/RIGHT EAR
LEFT HAND CONTROLS
M I C R 0 V 0 L T S
2 3 4 5 6 7 8 9 10 11 12 13 14 15 TIME 5' 10' 15' 20' 25 27
FIGURE 4
LEFT HANDERS GROUP BY TIME ACROSS SESSIONS (DIFFERENCE SCORES)
Left Hand/Left Ear
Left Hand/Both Ears
Left Hand/Right Ear
Left Hand Controls
-0.75
-1.25
TIME FIGURE 5
RIGHT HANDERS GROUP BY TIME ACROSS SESSIONS (RAW SCORES)
RIGHT HAND/LEFT EAR
RIGHT HAND/RIGHT EAR
RIGHT HAND/BOTH EAR
RIGHT HAND/CONTROLS
6 f
TME
5' 10' 15' 20' 25' 29
FIGURE 6
RIGHT HANDERS GROUP BY TIME ACROSS SESSIONS (DIFFERENCE SCORES)
RIGHT HAND/LEFT EAR
RIGHT HAND/RIGHT EAR
RIGHT HAND/BOTH EARS
RIGHT HAND/CONTROLS
0.5
M I C R O V O L T S
-2.5
TIME 30
Table 2 Group bv Time Analysis of Variance of Microvolt Change Scores Summary
Source of Variation Sum of Square df Mean Square F
Within Cells 5211.56 1012 5.15
Time 207.22 23 9.01 1.75*
Group by Time 219.47 69 3.18 .62
< .05
The final statistical procedure performed was a correlational analysis of the Edinburgh Handedness Inventory and the Dichotic Listening Task for Words. The Dichotic
Words task results in three scores consisting of the number of words correctly identified in the right ear, the number of words correctly identified by the left ear and the difference score obtained by subtracting the right ear score
from the left ear score. All of these scores were significantly correlated to the Edinbourgh Inventory. The correlations with the associated probability values are
listed in Table 3. 31
Table 3
Edinburgh Inventory and Dichotic Words Correlations
Dichotic Words: Right Ear Left Ear Difference
Edinburgh Inventory: 0.2980 -0.1857 0.2183
E = .002 £ = .035 £ = .014
Discussion
The four-way ANOVA indicated that performance differed significantly across time, based on hand preference and group. Two two-way ANOVAs were performed in an attempt to understand the three-way interaction. The results of the two-way ANOVAs indicated that the three-way interaction was the product of the Time effect in the Left Handed group.
The significant main effect for time indicates that
frontalis EMG levels did decrease and learning apparently took place.
Pooled means for all treatment and control groups
collapsed across the handedness condition reveal almost
identical patterns of microvolt change over time for the two
sessions (see Appendix H). Mean baseline microvolt readings
were 4.6 microvolts for session one and 4.8 microvolts for
session two. The greatest change from baseline was found in
the final recording, at 20 minutes following baseline, for
both sessions. This resulted in a 1.0 microvolt drop from 32
baseline in both sessions.
An examination of the mean difference scores for the control and feedback groups reveal that the greatest change from baseline was in the left ear, left hand group (see
Appendix G). The group with the least reduction in EMG level was the both ear groups which actually had an increase in EMG level from baseline. This was found in both right and left handed groups and is observed in both sessions although the magnitude of this difference is greater in session one and it appears to disappear at the end of session two. This is reflected in session one by a beginning mean microvolt reading of 5.1 microvolts for both right and left handers. However, in less than two minutes, the left handed subjects had reduced the microvoltage by .8 of a microvolt as opposed to only .2 microvolts change by the right handed group. This pattern continued throughout the first session with the final measurement resulting in a
2.2 microvolt change for left handers and a .8 change for
right handers. In session two the left handers began at 4.2 microvolts with the right handed subjects starting at 5.1 microvolts. While the left handed group retained mean microvolt measurements lower than the right handers for most
of the second session, the right handers did have the
greatest reduction. The right handed subjects mean change
from baseline was .74 microvolts as compared to .25 33
microvolts for the left handed group (see Appendix I).
Data for session one suggests an effect similar to that reported by Ginn and Harrell (1984), with the greatest EMG reduction from baseline found in the left ear group. This was observed with both right and left dominate subjects.
However, the difference was not statistically significant and was maintained only by the left handed group in the second session. This is consistent with a recent study by
Watson (1990) in which subjects were followed over six sessions. Watson reported a left ear superiority in the first session that was not maintained thereafter. Both
Watson (1990) and Ginn and Harrell (1984) restricted their study to right handed subjects. A unique finding in the current study not observed in previous research was the performance of the both ear groups. In this study the both ear groups only reduction in EMG levels was found in the
first session of the left handed group (.22 microvolts) and the second session of the right hand group (.41 microvolts) with all other sessions for this condition failing to show
reductions. Furthermore, the both ear group performed worse
than all other groups except for the second session with
right handed subjects in which the control group had the
least reduction in muscle tension. In Ginn and Harrell's
research the both ear group performance fell at a midway
level between the right ear group and left ear group. 34
reductions in EMG levels were also observed in the both ear group of the Watson study.
The performance over time of the single ear biofeedback groups reveals reductions in microvolt levels. Decreases in
EMG levels of frontalis muscle tension is initially observed following baseline and continues throughout both sessions in right and left ear feedback groups. This is in direct contrast to the control subjects whose EMG levels increased across sessions. This is consistent with the work of Ginn and Harrell (1984) as well as Watson who explained this in terms of self-stimulation. The assumption made is that when the brain is deprived of external stimulation it self- stimulates. As reported by Ginn and Harrell "asking subjects to sit and relax may actually increase their level of stress". Support for this "self-stimulation" hypothesis
is taken from studies on cerebral blood flow which have reported hyperfusion in frontal areas during rest (Mamo,
1983).
A significant correlation was observed on the Edinburgh handedness Inventory and the Dichotic Word Task. However,
the magnitude of this correlation is weak indicating that
subjects strongly lateralized by one measure may not be
lateralized by another. These findings are similar to that
of Ginn and Harrell (1984) who guestioned the notion of
laterality as a unitary concept and argues that laterality 35
of brain function may not be accurately reflected by a single measure.
The data obtained from the current study is highly variable. The reason for this variability is unknown although it may have resulted from the EMG equipment or printed, both of which were quite old. As a result of the high variability within the data possible effects may have been masked. This would appear to be supported by the consistency found in rank order of the current data and that of previous work by Ginn and Harrell (1984) and Watson
(1990). However, the lack of statistically significant findings in the current study forces the consideration of the results occurring simply by chance. Further research is needed to determine the presence of a laterality effect in the learning of a biofeedback task. Efforts in this area may be aided with designs in which a variety of physiological measures are taken, more sophisticated measuring and recording apparatus are utilized, and a
subject population more consistent with that found in
clinical practice is obtained.
In summary, the present study was unable to replicate
the findings of Ginn and Harrell (1984). No statistically
significant differences were found between groups. An
examination of the mean difference scores from baseline does
suggest a trend that was similar to the previous research 36
which found left ear feedback superior in right handed subjects. The present study suggests that if there is a differential ear effect it appears to be limited to the initial session with right handers but may be slightly more stable with left persisting into the second session.
Furthermore, if there is a left ear advantage to learning
EMG biofeedback, it appears to be not only subtle, but transient in nature. For these reasons clinical applicability would appear limited to early biofeedback training and possibly of limited usefulness at all. APPENDIX A
INFORMED CONSENT
37 38
APPENDIX A
INFORMED CONSENT
NAME OF SUBJECT_
I hereby give consent to Kenneth N. Walker to perform or supervise the following investigational procedure.
EMG biofeedback consisting of monitoring frontalis muscle activity via three surface electrodes placed on the forehead.
I have heard a clear explanation and understand the nature and procedure and the attendant discomforts or risks involved and the possibility of complications which might arise. I have heard a clear explanation and understand the benefits to be expected. I understand that the procedure or treatment to be performed is investigational and that I may withdraw my consent at any time without prejudice or penalty. With my understanding of this, having received this information and satisfactory answers to the questions I have asked, I voluntarily consent to the procedure designated above.
DATE
SIGNED: SUBJECT
SIGNED: WITNESS APPENDIX B
EDINBURGH HANDEDNESS INVENTORY
39 40
APPENDIX B
EDINBURGH HANDEDNESS INVENTORY
Name . Age Sex Date,
Please indicate your preference in the use of hands in the following activities by putting a + in the appropriate column. Where the preference is so strong that you would never try to use the other hand unless absolutely forced to, pUt ++. jf in any case you are indifferent, put a + in both columns. Please try to answer all of the questions, and only leave a blank if you have no experience at all with the object or task. Some of the activities require both hands. In these cases the part of the task, or object, for which hand preference is wanted is indicated in brackets. Left Right
1. Writing
2. Drawing
3. Throwing
4. Scissors
5. Toothbrush
6. Knife (without a fork)
7. Spoon
8. Broom (upper hand)
9. Striking a match (match)
10. Opening a box (lid)
i. Which foot do you prefer to kick with?
ii. Which eye do you use when using only one eye? 41 Appendix B, continued
Edinbourgh Laterality Quotients and Decile Values.
Laterality Quotients Decile Values
48 1
60 2
68 3
74 4
80 5
84 6
88 7
92 8
95 9
100 10 APPENDIX C
DICHOTIC WORD TASK
42 43
APPENDIX C
Directions For Dichotic Words
Apparatus and Operation: Stereophonic tape player with earphones and a dichotic words tape. Five minutes after turning on the tape playerr check the volume balance for several items with the ear phones in the normal position and also the reversed position. Subjectively equate the volume of the two channels. Instruct the subject that he/she will be wearing earphones. Say, "You are going to hear different words spoken to your two ears simultaneously, e.g. 'house' in this ear (point) and 'gown7 in the other ear (point). You are going to hear several pairs of different words. When the voice stops tell me all the words you heard, in any order you like. Guess if you are not sure. Again, listen with both ears and when the voice stops, state all the words you can remember.
Place the earphones over the ears of the subject. Starting with the practice trial, ensure volume levels are adequate. After the practice trial, stop the player and say, "Now you will hear four pairs of words in each ear. Call out as many words as you can when the voice stops." Play the tape continuously through the 10 trials, if possible. Make sure the subject does not engage in extraneous comments, thus missing a presentation. The tape may be stopped between trials. Do not replay missed segments
After the first presentation, reverse the earphones and run the test again.
Recording: Note on the response sheet the position of the earphones (N or R) and the order of the presentation.
Scoring: Total the number of correct responses for the left ear and the right ear in both normal and reversed conditions. Appendix c , continued 44
DICHOTIC WORDS SCORE SHEET
Name Sex Age Date Earphones - Normal (N) Earphones - Reversed
P. can pal P. pal can pick fit fit pick win rim rim win l.main rail rail main keep wheat wheat keep run come come run could book book could
2.rock top top rock week feel feel week tin pill pill tin sad have have sad
3. red wet wet red bid piq pig bid hack laq lag hack doll brought brought doll
4. lap raq rag lap diq pit pit diq buq mud mud buq fawn wall wall fawn
5. ham ran ran ham pod dim dim pod dip big big dip fun rum rum fun
6. rot mop mop rot pin dim dim pin cup but but cup meek neat neat meek
7. ruq bud bud ruq cab qap gap cab beam keen keen beam lid mitt mitt lid
8. hum ton ton hum mail rain rain mail nap bat bat nap dot loq log dot Appendix C, continued 45
9. bin will will bin fan tame tame fan tuck love love tuck bet den den bet
10.bomb gone bomb gone hat map map hat peel bean bean peel rib tip tip rib
Correct Correct Correct Correct
Total Right Correct_
Total Left Correct APPENDIX D
DICHOTIC WORD MEANS AND STANDARD DEVIATIONS
46 47
APPENDIX D
Means and Standard Deviations for the Dichotic Word Task
MEAN STANDARD DEVIATION
RIGHT EAR SCORE: 18.84 9.492
LEFT EAR SCORE: 11.87 6.686 APPENDIX E
GROUP INSTRUCTIONS
48 49
APPENDIX E
Group Instructions
Biofeedback-Both Ears: "Please sit quietly for five minutes. At the end of this time, you will begin to hear a tone. When you hear the tone, try to relax as much as possible. The more you relax, the lower the tone will be. Try to keep the tone as low as you can by relaxing for the remainder of the session."
Biofeedback-Left/Right Ear: "Please sit quietly for five minutes. At the end of this time, you will begin to hear a tone. You will hear the tone in one ear only. Do not be concerned about this. When you hear the tone, try to relax as much as possible. The more you relax, the lower the tone will be. Try to keep the tone as low as you can by relaxing for the remainder of the session."
Controls: "Please sit quietly for five minutes. At the end of this time, I will ask you to try to relax as much as possible for the remainder of the session." APPENDIX F
GROUP BY TIME ANALYSIS OF VARIANCE ON RIGHT HANDERS ACROSS SESSIONS
50 51
APPENDIX F
Group by Time Analysis of Variance on Right Handers Across Sessions
Source of Variance Sum of Squares df Mean Square
Within Cells 10293.26 1012 10.17
Time 218.45 23 9.50 .93
Group by Time 362.00 69 5.25 .52 APPENDIX G
MICROVOLT CHANGE SCORES FOR GROUP BY HANDEDNESS ACROSS SESSIONS
52 53
APPENDIX G
MICROVOLT CHANGE SCORES FOR GROUP BY HANDEDNESS ACROSS SESSIONS
RIGHT HANDERS
LEFT HANDERS
M 1.5 I C R O V O 1 — L T
C H 0.5 A N G E
S C O R E S -0.5
-1 LEFT EAR RIGHT EAR BOTH EARS CONTROLS BIOFEEDBACK GROUPS APPENDIX H
MEAN MICROVOLT LEVELS FOR SESSIONS ONE AND TWO ACROSS ALL GROUPS
54 55
APPENDIX H
MEAN MICROVOLT LEVELS FOR ALL SESSIONS ACROSS ALL GROUPS
SESSION 1
SESSION 2
6 T
M I C R O V O L T S
3 6 7 8 9 10 11 12 13 14 15 25' 5' 10' TIME 15* 20' APPENDIX I
MICROVOLT LEVELS FOR HANDEDNESS ACROSS GROUPS ON SESSION 1 AND 2
56 57
APPENDIX I
MICROVOLT LEVELS FOR HANDEDNESS ACROSS GROUPS ON SESSION 1
RIGHT HANDERS
LEFT HANDERS
u—Q—•-
M c R O V O L T S
3 6 7 8 9 10 11 12 13 14 15
5' 10' T\ME 15« 20' 25' Appendix I, continued 58
MICROVOLT LEVELS FOR HANDEDNESS ACROSS GROUPS ON SESSION 2
RIGHT HANDERS
LEFT HANDERS
M I C R O V O L T S
3 6 7 8 9 10 11 12 13 14 15 10' TIME . 5* 15 20' 25' APPENDIX J
CELL MEANS AND STANDARD DEVIATIONS FOR DIFFERENCE SCORES
59 60 APPENDIX J
DIFFERENCE SCORES POOLED ACROSS HANDEDNESS (CELL MEANS AND STANDARD DEVIATIONS)
SESSION 1
Intervel RIGHT EAR LEFT EAR BOTH EARS CONTROLS
Mean S.D. Mean S.D. Mean S.D. Mean S.D.
1 . 51 1. 51 67 2 . 73 -.46 3 . 17 . 28 1. 15 2 .49 1 . 36 1. 02 2 . 94 -.56 4 . 98 . 51 1. 53 3 . 85 1. 78 1. 18 3 . 21 -.46 4 . 97 . 57 1. 73 4 . 65 1. 4 3 1. 32 3 . 53 -.42 5 .41 . 39 1 . 96 5 1. 01 1. 97 1. 51 3 . 60 -.44 5.44 . 36 2 . 13 6 .91 1. 75 1. 71 3 . 75 50 5. 63 . 38 2 . 5 7 . 95 1. 96 1. 90 3 . 80 -.57 6. 11 .26 2 . 75 8 1.25 2 . 39 2 . 22 3 . 88 -.53 5. 89 . 37 2 . 96 9 1. 34 2 . 48 2 . 40 4 . 01 -.33 5.50 .49 10 2 . 95 .99 2 . 48 2 . 40 4 . 15 -.36 5.76 11 .41 3 . 39 1.29 2 . 99 2 . 46 4 . 29 -.43 5. 94 12 . 42 3 . 48 1.29 2 . 80 2. 64 4 . 38 -.04 5.27 . 60 3 . 59
SESSION 2 1 .24 3.67 .44 1.87 -.61 2.25 2 -.31 2.95 ,43 3.45 .68 2. 16 -.57 2.91 -.45 3 4.36 . 64 3 .95 1.12 2. 35 -.47 3.12 -.35 4 5.04 . 67 4.86 1. 15 2 .76 -.34 3 .10 -.27 5.47 5 .81 5.01 1.56 3.47 -.25 3.32 6 -.18 6.12 . 99 5.36 1.33 2 .73 -.32 3.54 -.03 7 6. 39 1. 15 5.73 1.37 2.87 -.36 3.64 8 . 19 6.51 1. 07 5.79 1. 61 2.96 -.37 3.74 9 .45 6.53 1. 10 5. 62 1.81 3 .36 -.15 3.86 10 .48 6. 87 1. 16 5.56 1.99 3.89 -.12 3.91 11 .62 6.90 1.21 5. 77 2. 12 4.25 -.09 3.91 . .69 6.92 12 1. 27 5. 60 2.22 4.54 -.22 4.01 .86 6.98 REFERENCES
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