Neuropsychologia, 0 Pergamon Press
Vol. Ltd.
16, pp. 483 to 489. 1978. Printed in Great
Britain.
THE INFLUENCE OF DIFFERENTIAL AUDITORY FEEDBACK UPON THE READING OF DYSLEXIC CHILDREN JOHN STUART GILLIS* and AGATHA E. SIDLAUSKAS Child Study Centre, University of Ottawa, Canada (Received 11 January 1977) Abstract-With the aim of investigating the possibility of a relationship between ear laterality and reading performance, ten dyslexic children were studied under different conditions of auditory feedback. It was found that oral reading was more rapid when feedback was directed mainly to the right ear instead of at equal intensity to both ears. The possible effect of amplifying high frequencies and attenuating low frequencies was also studied, but the results were not as clear. Consideration was given to theoretical interpretation similar to that which has been proposed for the well established right ear advantage in normals.
INTRODUCTION IN RECENT years a considerable body of literature has accumulated which indicates that linguistic stimuli (consonants, words, digits, syllables) are reported more rapidly and accurately when presented to the right ear [l-28], while nonlinguistic stimuli (melodies, environmental sounds) are processed more effectively when directed to the left ear [29-331. Influenced by the well-known proposals of a connection between cerebral dominance, inferred from sensory and/or motor asymmetry, and specific reading disability (ORTON [34] and ZANGWILL [35]), studies have also been carried out with the aim of investigating the possibility of a relationship between ear laterality and reading performance [36-41]. In reviewing this research, SATZ [42] has concluded that such a hypothesis “is only partially supported by the data�. The present study was undertaken with the goal of providing additional information about the question of ear laterality and reading by taking a somewhat different approach from past research. In previous work children have typically been classified into groups of good or normal readers who are then compared with poor or disabled readers with respect to the degree of ear asymmetry shown in dichotic or monaural listening tasks. The prediction has been that disabled readers, being less well lateralized, would show less right ear superiority than the normal readers. An alternative approach, suggested by the work of TOMATIS [43-461, would be to compare the ordinary reading behavior of dyslexic children with that which they produce when forced to listen with the right ear. The expectation would be that the children would read better when artificially lateralized. Since it has been suggested that the frequency of auditory information may be importantly involved in ear lateralization (SPELLACY and BLUMSTEIN [47]) and reading attainment (HENRY [48] and TOMATIS [43, 44]), it was also decided to investigate the possibility of frequency modification effects upon reading performance. *Present address: Canada E3B 5G3.
Department
of Psychology,
St. Thomas
483
University,
Fredericton,
New Brunswick,
484
JOHN STUARTGrurs and AGATHA E. SIDLAU~KAS
METHOD Participants Taking part in the study were 10 children (9 males, 1 female) with a mean age of 8.1 yr who were having considerable difficulty in learning to read. The children were selected on the basis of their nerformance on the 1973 Revised Wechsler Intelligence Scale for Children (WISC-R) and the Gates-McGinitie Reading Test (Form 1 of Level A or B depending upon age of the child). The children obtained a mean IQ score of 101.8 on the Verbal Scale of WISC and 112.6 on the Performance Scale. Combining the Vocabulary and Comprehension scores of the Gates-McGinitie Reading Test, the children scored at a Grade Level of 1.88, which when translated into an approximate reading age would be 6.9 yr, indicating that the children were on the average over more than 1 yr behind in reading. Apparatus A sketch of the basic components of the equipment developed by Tomatis that was used to control ear laterality and frequency modification may be found in Fig. 1. It may be seen that output from a microphone
Haadr*t
&
Amplifier
Microphone
FIG. 1. was amplified and then passed through either of two filtration systems (Fl or F2). Both the Fl and F2 channels could be set to modify sounds in a variety of ways. In the present study during frequency modification, F2 was made to amplify high and attenuate low frequencies, while Fl was adjusted in an opposite manner. The children were instructed to try to make a red light come on, which meant they would be hearing their voice passed through channel F2. The frequency modification of channel F2 is illustrated in Fig. 2. In addition to the frequency controls, there was also a voltage regulator which could be used to 60 t
FIG. 2. determine the intensity of auditory feedback at each ear. More detailed description his equipment may be obtained from: Secrap 22, Grande Rue, 92. Sevres, France.
and specitications
for
INFLUENCE
OF DIFFERENTIAL
AUDITORY
FEEDBACK
485
Tape recordings were made with a Revox A700 tape recorder. All equipment was located in a separate room in order to minimize distraction. Procedure
Once every 2 weeks for a period of 4 months (a total of 9 times; the children were tested under each of 4 conditions:
1. One hundred per cent auditory feedback to the right ear and only 10% to the left ear together with full frequency modification as illustrated in Fig. 2 (R + F). 2. One hundred per cent auditory feedback to the right ear and only 10% to the left ear but without any frequency modification (R). 3. One hundred per cent auditory feedback to both ears together with full frequency modification (F). 4. One hundred per cent auditory feedback to both ears without any frequency modification (C). The sequence of these feedback conditions was changed for each child at every test session according to a computer-generated random schedule. This procedurewas followed to control for the possibility of eider effects. Each of the 4 test periods lasted 5 min with a l-2 min break between them. During each period, the child read a short story from the SRA Reading Laboratory series. Each child began at a level in the series consistent with their score on the Gates-McGinitie test. If the children completed the story, they were asked the comprehension questions listed at the end of the story. A research assistant sat with the children when they read and helped them as seemed appropriate. This person was kept “blind” (unaware) as to the condition under which a child was reading at any particular time, since the settings of the apparatus were adjusted by a second research assistant in a separate room, who did not come into contact with the child or other assistant after changing the settings.
RESULTS In order to carry out the data analysis, tape recordings of the 1800 min (10 children, 9 test sessions, 4 periods/session of 5 min duration) of reading were listened to and the total number of words read was recorded for each of the 360 test periods. The main dependent variable of the study was then obtained in the form of the mean number of words read per minute during each 5 min test period. An analysis of variance was performed upon the means of the 10 children for each feedback condition during the 9 test sessions. This analysis indicated that the main effect for feedback conditions was significant, F (3,24) = 5.13, P < 0.01. Comparisons between the 4 conditions using Scheffe’s test showed a significant difference between the right ear only (R) and control condition (C), F (3,32) = 15.36, P < 0.01, as may be seen in Fig. 3. Inspection of the results for individual children indicated that the right ear condition was higher than the control condition in 9 of the 10 children. Looking at the children individually also indicated that the same 9 children scored higher in the frequency modification condition than in the control condition. In fact, it appeared that one child had responded very differently from the other children, having an overall rate of reading of 83.6 words/min compared to the 27.5 average (S.D. = 16.0) of the other children. Upon doing a secondary analysis of variance upon the mean scores of the remaining nine children over the nine test sessions, it was found that the Schaffe test now also indicated a significant difference between the frequency modification and control conditions F (3,32) = 9.95, P < 0.05. DISCUSSION The main outcome of the present investigation was that when feedback was given mainly to the right ear instead of to both ears, children with reading problems increased the rate of their reading performance. The question of course remains as to whether the more rapid reading observed was also “better” reading, for as BAKKER et al. [49] has pointed out, rate and quality of reading
486
JOHN STUART GILLISand AGATHA E. SIDLAUSKAS
,6 -
5-
x
4-
3-
A
x
x
\ 2-
x
I-
FIG. 3.
are not necessarily intertwined. The finding of a laterality effect with the easily scored, objective and precise measure of reading rate indicates that the undertaking of work with the more complicated, but theoretically more defensible, measures of errors and comprehension is now warranted. In the meantime, it seems worthwhile to give some consideration to theoretical explanations of the present results. These findings may be looked upon as lending support to the notion that dyslexic children have a problem in auditory lateralization (ORTON [34] and ZANGWILL[35]). The present results suggest that when listening to verbal stimuli coming at equal intensity to both ears, dyslexics do not focus more upon the right ear as normal children seem to do. Thus, they would not be making use of what has come to be known as the â&#x20AC;&#x153;right ear advantageâ&#x20AC;? (BERLIN et al. [2]). By requiring dyslexic children to listen with the right ear, it may be that they are now making better use of more efficient neural pathways to the left hemisphere (ROSENSWEIGand ROSENBLITH[50]) which is generally believed to be dominant for linguistic functions (GESCHWIND[51], LENNEBERG[52], PENFIELDand ROBERTS [53]). Yet, not only were the children in the present study required to passibely listen with the right ear as in dichotic listening, they were also being asked to engage in the complicated activity of oral reading, which among other things involves the movements of speech muscles. Influenced by anatomical evidence and the work of SUSSMAN[54], who found that the tongue was better able to coordinate its movements when the right ear processed the acoustic results of those tongue movements; BERLIN et al. [2] hypothesized that there is superior efficiency of interaction between the right ear and movements of the muscles of the vocal tract. Hence, it would again be expected that feedback to the right ear would
INFJJJENCE
OF
DIFFERENTIALAUDlrORY FEEDBACK
487
enhance oral reading. Such a formulation is quite similar to that which has been proposed by TOMATIS [45, 461 on the basis of his clinical research. Turning briefly to the present tentative results with regard to the frequency variable, it may be noted that SATZ [42] has pointed out that the procedure used in this study of defining poor readers as those whose intelligence scores were higher than their reading scores runs the risk of tending to produce “false positives” by misclassifying some good readers as poor readers. Future research may thus be more advantageously focused upon children w.ho also fall below some previously designated criterion for poor reading.
Acknowfe&ements-This study was assisted under Grant No. DM 202 from the Ontario Ministry of Health. The authors wish to express their thanks to ELAINE CAMPBELL, MANUEL MAPLES, JACK WAT~ZRS and MARY YEATMANfor their valuable assistance during various phases of the project.
REFERENCES 1. BARTZ, W. H., SATZ, P., FENNELL, E. and LALLY, J. R. Meaningfullness and laterality in dichotic listening. J. exp. Psychol. 73, 204-210, 1967. 2. BERLINTC. I., LOWE-BELL, S. S., CULLEN, J. K. and THOMPSON, C. L. Dichotic speech perception: an interpretation of right-ear advantage and temporal onset effects. J. Acoyst. Sot. Am. 53,699-709, 1973. 3. BEVER, T. G., HUR~G, R. R. and HANDEL, A. B. Analytic processing elicits right ear superiority in monoaurally presented speech. Neuropsychologiu 14, 175-181 i 1976. 4. BORKOWSKI, J. G.. SPREEN, 0. and STUTZ. J. Z. Ear preference in dichotic listening. Psychonomic Sci. 3, 547-548,i965. . 5. BRIGGS, G. G. and NEBES, R. D. The effects of handedness, family history and sex on the performance of a dichotic listening task. NeuropsychoZogiu 14, 129-133, 1976. 6. BROADBENT, D. E. and GREGORY, M. Accuracy of recognition for speech presented to the right and left ears. Q. JZ exp. Psychol. 16, 359-360, 1964. 7. BRYDEN, M. P. Ear preference in auditory perception. J. exp. Psychol. 65, 103-105, 1963. 8. BRYDEN, M. P. The manipulation of strategies of report in dichotic listening. Can. J. Psychol. 18, 126-138,1964. 9. COOPER, A., ACHENBACH,K., SATZ, P. and LEVY, C. Order of report and ear asymmetry in dichotic listening. Psychonomic Sci. 9, 97-98, 1967. 10. CURRY, F. K. W. and RUTHERFORD, D. R. Recognition and recall of dichotically presented verbal stimuli by right and left-handed persons. NeuropsychoIogia 5, 119-126, 1967. 11. DARWIN, C. J. Ear differences in the recall of fricatives and vowels. Q. JI exp. Psychol. 23,46-62,197l. 12. DIRKS, D. Perception of dichotic and monaural verbal material and cerebral dominance for speech.
Acta Oto-lar. 58, 73-80, 1964.
13. DOEHRING, D. G. and BARTHOLOMEUS,B. N. Laterality
9,425430,
effects in voice recognition.
Neuropsychologia
1971.
14. FRANKFURTER, A. and HONECK, R. P. Ear differences in the recall of monaurally presented sentences. Q. JI exp. Psychol. 25, 138-146, 1973. 15. GERBER, S. E. and GOLDMAN, P. Ear preference for dichotically presented verbal stimuli as a function of report strategies. J. Acousr. Sot. Am. 49, 1163-1168, 1971. 16. GOODGLASS, H. Developmental comparison of vowels and consonants in dichotic listening. J. Sp.
Hear. Res. 16,744-752,
1973.
17. HAGGARD, M. P. Encoding and the REA for speech signals. Q. JI exp. Psychol. 23, 34-45, 1971. 18. HAGGARD, M. P. and PARKINSON, A. M. Stimulus and task factors as determinants of ear advantages. Q. JI Exp. Psychol. 23, 168-177, 1971. 19. JONES, D. and SPREEN, 0. Dichotic listening by retarded children: the effects of ear order and abstractness. Child Develop. 38, 101-105, 1967. 20. KIMURA, D. Cerebral dominance and the perception of verbal stimuli. Can. J. Psycho/. 15, 166-171, 1961. 21. KIMURA, D. Speech lateralization in young children as determined by an auditory test. J. camp. physiol.
Psychol. 56, 899, 902, 1963.
22. LEVY, L. M. and BOWERS, D. Hemispheric asymmetry of reaction time in a dichotic discrimination task. Corfex 10, 18-25, 1974. 23. LOWE-BELL, S. S., CULLEN, J. K., Jr., BERLIN, C. I., THOMPSON,C. L. and WILLE~~, M. E. Perception of simultaneous dichotic and monotic monosyllables. J. Speech Heav. Nes. 13, 812-822, 1970.
488
JOHN STUARTGILLIS and AGATHAE. SIDLAU~KAS
24. SATZ, P., ACHENBACH,K., PATI?SHALL,E. and FENNELL,E. Order of report, ear asymmetry and handedness in dichotic listening. Cortex 1, 377-396, 1965. 25. WEISS, M. S. and HOUSE, A. S. Perception of dichotically presented vowels. J. Acourt. Sot. Am. 49, 96A, 1971. 26. SHANK~EILER,D. and STUDDERT-KENNEDY, M. Identification of consonants and vowels presented to left and right ears. Q. J1 exp. Psychol. 19, 59-63, 1967. 27. SHANON,B. Lateralization effects in reaction time to simple sentences. Cortex 10, 360-365, 1974. 28. SOMMERS,B. K. and TAYLOR,M. L. Cerebral speech dominance in language-disordered and normal children. Cortex 8, 224232, 1972. 29. BARTHOLOMEUS, B. Effects of task requirements on ear superiority for sung speech. Cortex 10,215-223, 1974. 30. CURRY, F. K. W. A comparison of left-handed and right-handed subjects on verbal and non-verbal dichotic listening tasks. Cortex 3, 343-352, 1967. 31. KIMURA, D. Left-right differences in the perception of melodies. Q. Jl exp. Psychol. 16,355-358, 1964. 32. SPELLACY,F. Lateral preferences in the identification of patterned stimuli. J. Acoust. Sot. Am. 47, 574-578, 1970. 33. SPREEN,O., SPELLACY,F. J. and REID, J. R. The effect of inter-stimulus interval and intensity on ear asymmetry for non-verbal stimuli in dichotic listening. Neuropsychologiu 8, 245-250, 1970. 34. ORTON, S. T. Reading, Writing and Speech Problems in Children. W. W. Norton, New York, 1937. 35. ZANGWILL, 0. L. Cerebral Domjnanve and its Nelation to Psychological Function. Oliver & Boyd, Edinburgh, 1960. 36. BAKKER]D. J. Ear-asymmetry with monaural stimulation : task inlhrences. Cortex 6, 36-41, 1970. 37. BAKKER.D. J.. SMINK,T. and REITSMA.P. Ear dominance and reading abilitv. Cortex 9.301-312. 1973. 38. BRYDEN;M. P. Laterality effects in dichotic listening: relations with handedness and reading ability in children. Neuropsychologia 8,443-450, 1970. 39. SPARROW,S. S. and SATZ, P. In Specific Reading Disability, D. J. BAKKERand P. SATZ (Editors), pp. 41-60. Rotterdam University Press, Amsterdam, 1970. 40. THOMSON,M. E. A comparison of laterality effects in dyslexics and controls using verbal dichotic listening tasks. Neuropsychologia 14, 243-246, 1976. 41. ZURIF, E. B. and CARSON,G. Dyslexia in relation to cerebral dominance and temporal analysis. Neuropsychologia 8, 351-361, 1970. 42. SATZ, P. Cerebral dominance and reading disability: an old problem revisited. In The Neuropsychology of Learning Disorders: Theoretival Approaches, R. KNIGHT and D. J. BAKKER (Editors). Univesrity Park Press, Baltimore, 1975. 43. TOMA~S, A. L’oreille et le Languge. Editions du Seuil, Paris, 1963. 44. TOMA~S. A. Education et Dvslexie. Editions ESF. Paris. 1972. 45. TOMA-& A. Vers I’Ecoute Humaine. Vol. 1. Editions ESF, Paris, 1974. 46. TOMAT~S, A. Vers I’Ecoute Humaine. Vol. 2. Editions ESF, Paris, 1974. 47. SPELLACY,F. and BLUMSTEIN, S. The inlluence of language set on ear preference in phoneme recognition. Cortex 6,43&439, 1970. 48. HENRY, S. Children’s audiograms in relation to reading attainments-III. Discussion, summary, and conclusions. J. Genet. Psychol. 71,49-63, 1947. 49. BAKKER,D. J., TEUNISSEN,J. and BOSCH,J. Development of laterality reading patterns. In The Neuropsychology of Learning Disorders: Theoretical Approaches, R. KNIGHTS and D. J. BAKKER(Editors). University Park Press, Baltimore, 1975. 50. ROSEN~~EIG, M. R. and ROSENBLITH,W. A. Responses to auditory stimuli at the cochlea and the auditory cortex. Prychol. Monogr. 67, l-26, 1953. 51. GESCHWIND,N. The organization of language and the brain. Science 170,94&944, 1970. 52. LENNEBERG,E. H. Biological Foundations of Language. Wiley, New York, 1970. 53. PENF~ELD,W. and ROBERTS,L. M. Speech and Brain Mechanisms. Princeton University Press, Princeton, 1959. 54. SUSSMAN,H. M. The laterality effect in lingual-auditory tracking. J. Acoust. Sot. Am. 49, 18741880 1971.
INFLUENCE
Ream6
Darts le 10 enfants
une
489
FEEDBACK
dirige
oralo
des hautes
fr&quences.
Les r6sultats
interpretation
th6orique
de l'orcillc
conditions
dtait
plus
fr&quences
proche
droite
chez
de celle
quand
la
on a Studi diff6rP.
le icedback
Urn eine
Beziehung
magliche
stung zu untersuchen, Bedingungen
vor sich ging, wenn die
durch das rechte Ohr geleitet
gleicher
Effekt bei Amplitudenerweiterung
IntensitSt niedriger
durch beide Ohren. Auch
Frequenzen
gezogen wurde eine theoretische ist.
hoher Frequen-
wurde untersucht,
waren nicht sehr eindeutig. Interpretation
die fiir die gut belegte Rechtsohrdominanz worden
und Leselei-
Rtickkopplung gepriift. Es
schneller
ein moglicher
aber die Ergebnisse
pour
Kinder unter ver-
wurde anstatt
zen und -verminderung
des
On envisaqc
qui a 6t6 propo&e
10 dyslexische
auditiver
Riickkopplung haupts%chlich
nets.
zwischen Ohrdominanz
wurden
fand sich, dafl Lautlesen
attenuation
aussi
les ncxmau~.
Zusammenfassung:
geschlagen
entre
de feedback
raplde
et d'une
ne sent pas
Deutschsprachise
schiedenen
relation
de lecture,
principnlement vefs lâ&#x20AC;&#x2122;ore~lle droite au lieu de dormer Goale aux 2 oreilles. On a @tudie aussi un effet possible
amplification
l'avantaqe
une possible
et les performances
sous diffgrentes
que la lfcturc
une intensite basses
but de rechercher
auriculairc
dyslcxiques
On a trouv6
d'une
AUDITORY
:
lateralisation
@tait
OF DIFFERENTIAL
In Erwagung ahnlich
bei Wormalen
jener, vor-