Psychological Medicine, 1978, 8, 111-117 Printed in Great Britain
Dichotic listening and allusive thinking M. S. ARMSTRONG, 1 A. P. BLASZCZYNSKI
AND
N.
MCCONAGHY
From the New South Wales Institute of Psychiatry, The Prince of Wales Hospital, and The School of Psychiatry, University of New South Wales
Previous work suggests that allusive thinkers have a broader attentional process associated with weak central inhibition. The method of dichotic stimulation was used to investigate this concept. Sixty-three university students completed a battery of tests including 2 dichotic listening tasks. The Object Sorting Test was used as a measure of allusive thinking. Allusive thinkers showed a trend towards impaired shadowing performance. Mislabelling of shadow as distractor words and vice versa, on recall and recognition tasks, showed the strongest correlation with allusive thinking. Such mislabelling was considered to reflect impaired discrimination learning, and provides further support for a hypothesis relating allusive thinking to weak Pavlovian central inhibition.
SYNOPSIS
INTRODUCTION McConaghy (1960, 1961) suggested that allusive thinking, a cognitive style initially recognized in schizophrenics, occurred in a proportion of the normal population and indicated the presence of a predisposition to develop schizophrenia. In a series of studies (Lovibond, 1954; McConaghy, 1961; McConaghy & Clancy, 1968; Barr & McConaghy, 1972) the Lovibond Object Sorting Test (OST) (Lovibond, 1966) was used to measure the presence of allusive thinking in both schizophrenics and normals. Lidz and his colleagues (Rosman et al. 1964) confirmed McConaghy's finding that parents of thoughtdisordered schizophrenics obtained significantly higher scores on the OST than did control parents. Armstrong & McConaghy (1977) advanced evidence in support of a Pavlovian model of allusive thinking. They proposed that allusive, as compared with non-allusive thinkers, have a broader but less intense attention process associated with weaker central inhibition. It was predicted from this model that allusive thinkers would demonstrate a 'word halo' effect; that is, on word tests which require judgements of similarity of meaning, allusive thinkers would tend to choose more remote or unusual words as similar in meaning. 1 Address for correspondence: Dr M.S.Armstrong, Psychiatric Unit, Prince of Wales Hospital, Randwick, N.S.W. 2031, Australia.
The Word Halo Test (WHT) and a Word Sorting Test (WST) were administered to 63 university students using the OST as a measure of allusive thinking. The prediction was supported. The choice of more-remotely associated words by allusive thinkers in the WHT did not depend upon selection of a larger number of words. This finding could be accounted for by a model of allusive thinking stressing a process of equalization of competing response tendencies rather than by a model explaining allusive thinking as produced by global conceptual overinclusion. A 'word halo' model of allusive thinking emphasizes the tendency of allusive thinkers to conceptualize the world in a less sharply discriminating way. Dichotic listening and overinclusive thinking Dichotic stimulation, the technique of simultaneous presentation of auditory stimuli to each ear of a subject through stereo headphones, was used by Payne et al. (1970) to investigate the attention process in schizophrenic patients. Payne and his colleagues hypothesized that overinclusive thinking in schizophrenia was produced by failure of a central filtering mechanism to exclude irrelevant material. They predicted that a defective filter would prevent overinclusive schizophrenic subjects from attending efficiently to auditory stimuli delivered to one ear when distracting stimuli were delivered simultaneously
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M. S. Armstrong, A. P. Blaszczynski and N. McConaghy
to the other ear. Under these conditions overinclusive schizophrenics would show overinclusive perception. A battery of measures of overinclusive thinking (Payne & Friedlander, 1962) was administered to 12 clinically overinclusive schizophrenics, 12 clinically non-overinclusive schizophrenics and 12 normal controls. The subjects were then required to shadow, that is repeat aloud, material delivered to one ear while ignoring distracting material delivered to the other ear. Clinically overinclusive schizophrenics differed significantly from the normals on the tests of overinclusive thinking and made significantly more shadowing errors than both the clinically non-overinclusive schizophrenics and normals. In turn, the non-overinclusive schizophrenics made significantly more shadowing errors than did normals. No significant relationship was found between the measures of overinclusive thinking and the measures of overinclusive perception. Payne and his colleagues concluded that overinclusive thinking and overinclusive perception may be independent. The finding that clinically overinclusive schizophrenics showed both forms of overinclusion was explained as due to an artefact in selection: their clinical definition of overinclusion included both thinking and perceptual distractability. More recent developments suggest that abandonment of the hypothesis that a relationship exists between overinclusive styles of thinking and dichotic listening performance may be premature. Payne (1973) stated that overinclusion, as measured by his battery of tests for overinclusive thinking, does not characterize chronic schizophrenia. Harrow et al. (1972) distinguished between 'behavioural overinclusion', the type of overinclusive thinking measured by Payne's battery, and 'conceptual overinclusion', the type of overinclusive thinking measured by Harrow et a/.'s scoring of the OST, and presumably related to allusive thinking as measured by Lovibond's method of scoring the OST. The possibility seems worthy of investigation that a relationship exists between a cognitive style related to conceptual, rather than behavioural, overinclusion and less efficient performance on dichotic listening tasks.
THE PRESENT STUDY A battery of tests, including the OST, WHT, WST, and dichotic listening tasks was administered to a group of 63 university students by one of the authors (M.S. A.), the OST being administered last. Details of the subjects and the administration and scoring of the OST, WHT and WST have been previously reported (Armstrong & McConaghy, 1977). All subjects completed a brief clinical test of hearing before proceeding with the dichotic listening tasks. It was predicted that subjects who obtained scores on the OST indicative of allusive thinking would show significantly more errors in shadowing performance than non-allusive thinkers. METHOD Dichotic listening tasks The procedure was adapted from Wishner & Wahl (1974). There were 5 experimental conditions. (1) Shadowing without distraction (SWOD). The subject was required to repeat aloud, as he heard them, a list of words delivered binaurally at a rate of 50 words per minute (w.p.m.). The remaining conditions all involved shadowing with distraction at slow (25 w.p.m.) or fast (50 w.p.m.) rates of presentation with induction of a simple or compound mental set. These conditions are summarized below: (2) Simple set with slow rate of presentation (SI). The subject is asked to repeat aloud words delivered through the right ear while ignoring those delivered through the left ear. (3) Compound set with slow rate of presentation (S2). The subject is asked to repeat aloud words delivered through the right ear but at the same time to try and attend to rather than ignore words delivered to the left ear. (4) Simple set with fast rate of presentation (Fl). This condition is similar to SI, except that a fast rate of presentation is employed. (5) Compound set with fast rate of presentation (F2). This condition, similar to S2 except that a fast rate of presentation is employed, was added to the procedure of Wishner & Wahl to provide an extra degree of difficulty for normal subjects. In addition to the above 5 tasks subjects also
Dichotic listening and allusive thinking
completed a dichotic word test designed by Quinn (1972, 1975) to test for cerebral dominance. Preparation of dichotic tape
The conventional technique using an electronic metronome was employed. Material for the 2 channels was recorded utilizing Revox tape recorders, with the same male voice on both channels, and later combined on a third tape recorder. Care was taken to match the amplitude of the 2 channels by monitoring VU meters during recording. Polygraphic recordings showed that 84 % of dichotic word pairs were synchronized as to onset within 65 ms (mean 37-3 ms). Presentation rates corresponded to a mean interpair interval of 855 ms under fast conditions and 2104 ms under slow conditions. The interpair interval is the interval between the beginning of one pair and the end of the preceding pair, the duration of a pair being denned by the duration of the longer item of that pair.
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made familiar with the equipment by listening to initial instructions through the headphones. Instructions were given for each condition as previously outlined. Following each of conditions 2-5, subjects were asked to recall as many D-words as they could and then as many S-words as they could. The recall task was followed each time by an auditory recognition task. This consisted of a binaural recording of the 7 S-words embedded at random in a list of 14 other words. In SWOD the 14 words were all control words (C-words), that is words not previously heard. In the other conditions, 7 of the 14 were C-words, and 7 were the D-words just presented. Subjects were asked to repeat aloud from the list, which was delivered at 25 w.p.m., those words which they recognized as words just shadowed. All responses were recorded by M.S.A. on an answer sheet which listed the complete protocol for each condition. After condition S2, subjects were given a 15-minute break during which they completed an unrelated task. Measures
Materials The words used in the shadowing with distraction conditions of the experiment were all Thorndike-Lorge AA words, that is words used more frequently than 100 times in a million in the samples of language investigated by Thorndike & Lorge (1944). For each condition words were balanced as to 'concreteness' and 'meaningfulness' between shadow, distractor and control lists as these variables have been shown to be important in perceptual and learning processes (Paivio et al. 1968). Words used in the shadowing without distraction and slow conditions were of 2 syllables; those in fast conditions were of one syllable. In each condition the words to be shadowed (S-words) consisted of a list of 7 words repeated 6 times in random order. The distractor words (D-words) consisted of a list of 7 words repeated 6 times in the same order. Presentation condition
A TEAC A-2300-S two-channel tape deck delivered the verbal material through a pair of Superex ST-V stereo headphones. Subjects were
The following scores were derived from each individual record. Shadowing errors were the total number of errors made in shadowing. These included failures of response, incorrect response and reporting of whole or part of distractor words. Where an incorrect response closely approximated the correct response (e.g. ' buddy' instead of 'body') one-half of one error was counted. Recall errors included recall of S-words as D-words and vice versa, and recall of words not presented to the subject. The recall data were also scored employing a second method. D-recall was the number of D-words recalled in each condition irrespective of whether they had been identified as D or S. Similarly S-recall referred to S-words recalled, irrespective of their identification as D or S. D-recognition and C-recognition errors were scored in the recognition tasks. These were respectively the number of D- and of C-words erroneously identified as S-words. An index of cerebral laterality was derived for each subject. The number of words correctly recalled from each ear in the Quinn Dichotic Word Test (Quinn, 1972, 1975) was determined. The index was then calculated for each individual PSM S
M. S. Armstrong, A. P. Blaszczynski and N. McConaghy
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Table 1. Summary of results for shadowing, recognition and recall data for 63 subjects
51 - total shadowing errors 52 - total shadowing errors Fl - total shadowing errors F2 - total shadowing errors Recall errors - all conditions (RCU C-recognition errors all conditions (CREC) D-recognition errors all conditions (DREC)
Mean
S.D.
Range
Correlation with OST score
2-51
2-28
0-10
015
2-24
2-45
0-12
017
6-57
5-40
0-26
0-28*
7-29
4-86
0-24
004
4-38
3-29
0-16
—
0-65
1-46
0-9
—
Factor 1
Factor 2
—
0-6075 0-7599 0-8492 0-7971 01667 00942 -00473
01432 01523 -00274 -00240 0-8519 0-7920 0-8838
3-67
310
0-15
* P < 005.
Table 2. Correlation matrix for shadowing, recognition and recall data si SI S2 Fl
F2 RCL
CREC DREC
S2
Fl
F2
RCL
CREC
— — 008 004 004
— — — 0-51 0-66
— — — — 0-56
—
0-30 0-43 0-27 0-26 011 004
Table 3. Factor matrix of data from Table 2 using principal factor without iterations
0-50 0-52 0-23 017 010
— 0-57 011 012 -007
using the formula (R —L)/(R + L) where R and L are the numbers of words recalled from right and left ears respectively. The index ranges from + 1 for complete right dominance to - 1 for complete left dominance. RESULTS No significant association was found between the index of cerebral laterality and OST score (r = 0-14, NS). Shadowing, recall, and recognition errors A summary of results on these measures is given in Tables 1 and 2. For brevity of presentation the recall and recognition errors have been summed across all conditions. (A linear combination of variables was able to account for
SI S2 Fl F2 RCL CREC DREC
Factor 1
Factor 2
0-5661 0-6915 0-6507 0-6118 0-6576 0-5636 0-5090
-0-2629 -0-3499 -0-5464 -0-5115 0-5667 0-5644 0-7240
Table 4. Factor matrix after Varimax rotation with Kaiser normalization of data from Table 2
SI S2
Fl F2 RCL CREC DREC
41-7 % of the variance in the case of recall errors and 51-7 % in the case of erroneous recognition of distractor words.) To investigate the relationship between allusive thinking and the various measures of auditory perception, the data in Table 2 were reduced by performing a principal components analysis (Nie et al. 1975). The factor matrix obtained is given in Table 3. Factor scores on the general first factor were found to be highly significantly related to OST score (r = 044, P < 0001). Inspection of the intercorrelations between different errors on the dichotic listening tasks (Table 2) suggested that measures concerned with shadowing performance and memory (recognition and recall) were relatively independent. Advantage was taken of a Varimax rotation to isolate the effects of these two groups of measures. The factor matrix after rotation is given in Table 4. The correlations of factor scores with OST score were: factor 1, r = 0-19, NS; factor 2, r = 0-47, P < 0-001. As factor 2 in the Varimax rotation reflects memory for the dichotically presented words it is possible that the relationship between OST score and factor 2 could be determined by some difference in learning or remembering ability on the part of the allusive thinkers. One aspect of
Dichotic listening and allusive thinking
such ability is reflected in the number of S- and D-words actually remembered (irrespective of whether they are correctly identified as S- or D-words). Neither recall of S-words nor recall of D-words showed any significant relationship with OST score. (The correlation of OST score with recall of S-words was r = - 0 0 8 , NS. That of recall of D-words under the individual conditions was as follows: SI, r = -0-19; S2, r = - 0 1 6 ; Fl, r = - 0 0 4 ; F2, r = 0 1 1 ; all NS.) Nature of shadowing errors
Shadowing errors consisted largely of omissions and misperceptions. Only 17-4% of shadowing errors consisted of ' interpenetrations' of Dwords. DISCUSSION The results indicate the presence of a relationship between allusive thinking and impaired performance on a dichotic listening task. Allusive thinking and shadowing performance
There was a trend for impaired shadowing performance to be associated with allusive thinking. In only 1 of the 4 shadowing with distraction conditions (Fl) did this trend reach statistical significance (r = 0-28, P < 005). In a study of 24 'high-creative' and 24 'lowcreative' university students selected on the basis of scores on the Wallach & Kogan (1965) tests of creative thinking, Dykes & McGhie (1976) demonstrated differences in shadowing performance between the 2 groups on a dichotic listening task analogous to that used in the present study. In Dykes & McGhie's study both groups of students completed the Lovibond OST, the high-creative students obtaining a mean score of 23-7 (range 13-40) and the lowcreative students a mean score of 2-4 (range 0-6). On the dichotic listening task the highcreative students made significantly more errors in shadowing than the low-creative students under conditions in which there was a strong associative connection between words in S-D pairs. If there is a relationship between allusive thinking and impaired shadowing performance,
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it seems possible that it may be manifest only when mental processes are strained. In the present study a relationship between impaired shadowing performance and allusive thinking was found under condition Fl (significantly more difficult than SI and S2) but not under F2, which is of a similar degree of difficulty to Fl in terms of the number of shadowing errors made (Table 1). Work on the WHT and WST (Armstrong & McConaghy, 1977) suggests a possible explanation for the occurrence of shadowing errors in allusive thinkers in Dykes & McGhie's strong, but not weak, associative condition. Moray (1959) noted the tendency of subjects to hear their own name in a dichotic listening task even when it was presented to the unattended ear. Information from the unattended ear is attenuated but may reach awareness if the threshold for the information is low (Treisman, 1960; Broadbent, 1970). In Dykes & McGhie's study the word presented to the attended ear could be expected to excite neural linkages associated with that word concept, so producing a lowering of threshold for the excitation of closely associated word concepts. In allusive thinkers, owing to their broader attentional process, the lowered threshold is more likely to extend to the strongly associated words delivered to the unattended ear. These words may reach consciousness and act as strong competing response tendencies, thus increasing the probability of occurrence of shadowing errors. Allusive thinking and misperception of stimulus words
If the relationship between allusive thinking and shadowing performance suggested by the present study proves replicable, it would appear that, at least under conditions of perceptual rivalry, allusive thinkers misperceive more auditorily presented words than do non-allusive thinkers. Moon et al. (1968) provided evidence that misperception of stimulus words in a word association task was significantly commoner in a group of 20 thought-disordered schizophrenics than in a group of normal controls matched on variables which included age, intelligence and auditory acuity. Moon et al. argued that such auditory misperceptions may account for many, 8-2
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M. S. Armstrong, A. P. Blaszczymki and N. McConaghy
although not all, idiosyncratic associations to stimulus words. Results with the Word Halo Test and Word Sorting Test (Armstrong & McConaghy, 1977; Tucker, 1977) provided evidence that allusive thinkers show more distant associative responses in situations where the stimulus words are presented visually so that auditory misperception was not in question. Recall and recognition data Highly significant differences were found between allusive and non-allusive thinkers when aspects of the dichotic listening task dependent on memory were examined. On the Varimax rotation, factor 2 was highly significantly related to OST score. The major part of the variance shared by OST performance scores and factor 2 was accounted for by errors in recognition and recall rather than by errors in shadowing performance. A significant proportion of these errors was due to mislabelling of D-words as S-words and vice versa. Two hypotheses could account for this mislabelling shown maximally by allusive thinkers. A peripheral filtering deficit could lead to inappropriate inclusion of D-words in the SI and Fl conditions. ('Filtering' in the present sense refers to the attentuation of information presented to the non-attended ear which thus fails to reach conscious awareness.) If this hypothesis were correct it would be expected that shadowing performance, which offers the most direct information about instantaneous attentional processes, would be particularly impaired in allusive thinkers in those conditions where filtering was required (SI, Fl) as compared with those where it was not (S2, F2). Though a significant relationship between shadowing performance and OST was found in condition Fl, performance on Fl as compared with F2 and SI as compared with S2 did not differ significantly. Furthermore, if mislabelling were a result of a hypothesized peripheral filtering deficit, subjects with this deficit should recall a greater number of D-words (D-recall) in those conditions where filtering was required. D-recall was not significantly associated with OST score in either SI (r = -0-19) or Fl (r = 0-04). The second hypothesis accounting for the mislabelling of S- and D-words relates to an
alteration of central processing in the encoding and/or retrieval of the words. The experimental situation represents a learning task with two levels: the first level involves learning which words have been presented; the second level involves learning which group (S or D) words have been presented in. Allusive and nonallusive thinkers do not differ in respect of the first level as judged by the number of S-words recalled in shadowing with or without distraction. However, in relation to the second level, failure of allusive thinkers to learn which group words belong to could account for the observed relationship. Impairment of discrimination learning is one consequence predicted by a theory relating allusive thinking to weak central inhibition (Lovibond, 1954). Payne et al. (1959) suggested that overinclusive thinking in schizophrenics could be due to defective discrimination learning. In addition to recall errors and D-recognition errors the third variable significantly contributing to the rotated factor 2 was C-recognition errors, the recognition of control words (that is words not previously presented) as S-words. Unless it is replicated in a further study, it seems unwise to attach significance to this relationship. Only one-third of the subjects included any control words, and the major part of the relationship to allusive thinking appeared to depend on high C-recognition scores obtained by the 2 highest scorers on the OST. CONCLUSIONS The results of this study support the hypothesis that allusive thinking is produced by a Pavlovian weakness of central inhibition. There was a trend for allusive thinkers to show impaired shadowing performance. Confronted simultaneously with 2 competing response tendencies, allusive thinkers show greater difficulty than non-allusive thinkers in attending to the one while excluding the other. This finding, which appears to be determined by an alteration in processing at a central rather than a peripheral level, is consistent with the notion advanced by McConaghy (McConaghy, 1974; Armstrong & McConaghy, 1977) that allusive thinkers have a broader, less sharply focused attentional process.
Dichotic listening and allusive thinking
More powerful evidence in support of a hypothesis of weak central inhibition is the finding of a strong relationship between allusive thinking and impaired discrimination learning, as demonstrated by mislabelling of S- and D-words. This project was supported by the National Health and Medical Research Council of Australia and was made possible by the appointment of the first author as a Research Fellow of the NSW Institute of Psychiatry. The help of Ken Norcross, Peter Tucker and Dr Peter Quinn and the statistical advice of Megan Neilson are gratefully acknowledged.
REFERENCES Armstrong, M. S. & McConaghy, N. (1977). Allusive thinking, the Word Halo, and verbosity. Psychological Medicine 7, 439-445. Barr, R. F. & McConaghy, N. (1972). Conditioning in relation to conceptual thinking. British Journal of Psychiatry 121, 299-310. Broadbent, D. E. (1970). Stimulus set and response set: two kinds of selective attention. In Attention: Contemporary Theories and Analysis (ed. D. Mostofsky), pp. 51-60. Appleton-Century-Crofts: New York. Dykes, M. & McGhie, A. (1976). A comparative study of attentional strategies of schizophrenic and highly creative normal subjects. British Journal of Psychiatry 128, 50-56. Harrow, M., Himmelhoch, J., Tucker, G., Hersh, J. & Quinlan, D. (1972). Overinclusive thinking in acute schizophrenic patients. Journal of Abnormal Psychology 79, 161-168. Lovibond, S. H. (1954). The object sorting test and conceptual thinking in schizophrenia. Australian Journal of Psychology 6, 52-70. Lovibond, S. H. (1966). Interim Manual for the Object Sorting Scales. Australian Council for Educational Research: Melbourne. McConaghy, N. (1960). Modes of abstract thinking and psychosis. American Journal of Psychiatry 117, 106-110. McConaghy, N. (1961). The measurement of an inhibitory process in human higher nervous activity: its relation to allusive thinking and fatigue. American Journal of Psychiatry 118, 125-132. McConaghy, N. (1974). Allusive thinking and the ocular angle alpha. In Essays on Schizophrenia Essay no. 7. Ethnor Ltd: Sydney.
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McConaghy, N. & Clancy, M. (1968). Familial relationships of allusive thinking in university students and their parents. British Journal of Psychiatry 114, 1079-1087. Moon, A. F., MefTerd, R. B., Jr, Wieland, B. A., Pokorny, A. D. & Falconer, G. A. (1968). Perceptual dysfunction as a determinant of schizophrenic word associations. Journal of Nervous and Mental Disease 146, 80-84. Moray, N. (1959). Attention in dichotic listening: affective cues and the influence of instructions. Quarterly Journal of Experimental Psychology 11, 56-60. Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K. & Bent, D. H. (1975). Statistical'Package for the Social Sciences. McGraw-Hill: New York. Paivio, A., Yuille, J. C. & Madigan, S. A. (1968). Concreteness, imagery, and meaningfullness values for 925 nouns. Journal of Experimental Psychology Monograph Supplement, 76, no. 1, part 2, 1-25. Payne, R. (1973). Cognitive abnormalities. In Handbook of Abnormal Psychology (ed. H. J. Eysenck), pp. 420-483. Pitman: London. Payne, R. & Friedlander, D. (1962). A short battery of simple tests for measuring overinclusive thinking. Journal of Mental Science 108, 362-367. Payne, R., Matussek, P. & George, E. I. (1959). An experimental study of schizophrenic thought disorder. Journal of Mental Science 105, 627-652. Payne, R., Hochberg, A. C. & Hawks, D. V. (1970). Dichotic stimulation as a method of assessing the disorder of attention in overinclusive schizophrenic patients. Journal of Abnormal Psychology 76, 185-193. Quinn, P. T. (1972). Stuttering: cerebral dominance and the dichotic word test. Medical Journal of Australia 2, 639-643. Quinn, P. T. (1975). The investigation of neurological factors in stutterers. Unpublished Ph.D. Thesis, University of New South Wales. Rosman, B., Wild, C , Ricci, J., Fleck, S. & Lidz, T. (1964). Thought disorder in the parents of schizophrenic patients: a further study utilizing the object sorting test. Journal of Psychiatric Research 2, 211-221. Thorndike, E. L. & Lorge, I. (1944). The Teacher's Wordbook o/30000 Words. Teachers College, Bureau of Publications: New York. Treisman, A. M. (I960). Contextual cues in selective listening. Quarterly Journal of Experimental Psychology 12, 242-248. Tucker, P. K. (1977). Allusive thinking and creativity in high school students. Unpublished B.Sc (Med.) thesis, University of New South Wales. Wallach, M. A. & Kogan, N. (1965). Modes of Thinking in Young Children: A Study of the Creativity-Intelligence Distinction. Holt, Rinehart and Winston: New York. Wishner, J. & Wahl, O. (1974). Dichotic listening in schizophrenia. Journal of Consulting and Clinical Psychology 42, 538-546.
Dichotic listening and allusive thinking M. S. ARMSTRONG, 1 A. P. BLASZCZYNSKI
AND
N.
MCCONAGHY
From the New South Wales Institute of Psychiatry, The Prince of Wales Hospital, and The School of Psychiatry, University of New South Wales
Previous work suggests that allusive thinkers have a broader attentional process associated with weak central inhibition. The method of dichotic stimulation was used to investigate this concept. Sixty-three university students completed a battery of tests including 2 dichotic listening tasks. The Object Sorting Test was used as a measure of allusive thinking. Allusive thinkers showed a trend towards impaired shadowing performance. Mislabelling of shadow as distractor words and vice versa, on recall and recognition tasks, showed the strongest correlation with allusive thinking. Such mislabelling was considered to reflect impaired discrimination learning, and provides further support for a hypothesis relating allusive thinking to weak Pavlovian central inhibition.
SYNOPSIS
INTRODUCTION McConaghy (1960, 1961) suggested that allusive thinking, a cognitive style initially recognized in schizophrenics, occurred in a proportion of the normal population and indicated the presence of a predisposition to develop schizophrenia. In a series of studies (Lovibond, 1954; McConaghy, 1961; McConaghy & Clancy, 1968; Barr & McConaghy, 1972) the Lovibond Object Sorting Test (OST) (Lovibond, 1966) was used to measure the presence of allusive thinking in both schizophrenics and normals. Lidz and his colleagues (Rosman et al. 1964) confirmed McConaghy's finding that parents of thoughtdisordered schizophrenics obtained significantly higher scores on the OST than did control parents. Armstrong & McConaghy (1977) advanced evidence in support of a Pavlovian model of allusive thinking. They proposed that allusive, as compared with non-allusive thinkers, have a broader but less intense attention process associated with weaker central inhibition. It was predicted from this model that allusive thinkers would demonstrate a 'word halo' effect; that is, on word tests which require judgements of similarity of meaning, allusive thinkers would tend to choose more remote or unusual words as similar in meaning. 1 Address for correspondence: Dr M.S.Armstrong, Psychiatric Unit, Prince of Wales Hospital, Randwick, N.S.W. 2031, Australia.
The Word Halo Test (WHT) and a Word Sorting Test (WST) were administered to 63 university students using the OST as a measure of allusive thinking. The prediction was supported. The choice of more-remotely associated words by allusive thinkers in the WHT did not depend upon selection of a larger number of words. This finding could be accounted for by a model of allusive thinking stressing a process of equalization of competing response tendencies rather than by a model explaining allusive thinking as produced by global conceptual overinclusion. A 'word halo' model of allusive thinking emphasizes the tendency of allusive thinkers to conceptualize the world in a less sharply discriminating way. Dichotic listening and overinclusive thinking Dichotic stimulation, the technique of simultaneous presentation of auditory stimuli to each ear of a subject through stereo headphones, was used by Payne et al. (1970) to investigate the attention process in schizophrenic patients. Payne and his colleagues hypothesized that overinclusive thinking in schizophrenia was produced by failure of a central filtering mechanism to exclude irrelevant material. They predicted that a defective filter would prevent overinclusive schizophrenic subjects from attending efficiently to auditory stimuli delivered to one ear when distracting stimuli were delivered simultaneously
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M. S. Armstrong, A. P. Blaszczynski and N. McConaghy
to the other ear. Under these conditions overinclusive schizophrenics would show overinclusive perception. A battery of measures of overinclusive thinking (Payne & Friedlander, 1962) was administered to 12 clinically overinclusive schizophrenics, 12 clinically non-overinclusive schizophrenics and 12 normal controls. The subjects were then required to shadow, that is repeat aloud, material delivered to one ear while ignoring distracting material delivered to the other ear. Clinically overinclusive schizophrenics differed significantly from the normals on the tests of overinclusive thinking and made significantly more shadowing errors than both the clinically non-overinclusive schizophrenics and normals. In turn, the non-overinclusive schizophrenics made significantly more shadowing errors than did normals. No significant relationship was found between the measures of overinclusive thinking and the measures of overinclusive perception. Payne and his colleagues concluded that overinclusive thinking and overinclusive perception may be independent. The finding that clinically overinclusive schizophrenics showed both forms of overinclusion was explained as due to an artefact in selection: their clinical definition of overinclusion included both thinking and perceptual distractability. More recent developments suggest that abandonment of the hypothesis that a relationship exists between overinclusive styles of thinking and dichotic listening performance may be premature. Payne (1973) stated that overinclusion, as measured by his battery of tests for overinclusive thinking, does not characterize chronic schizophrenia. Harrow et al. (1972) distinguished between 'behavioural overinclusion', the type of overinclusive thinking measured by Payne's battery, and 'conceptual overinclusion', the type of overinclusive thinking measured by Harrow et a/.'s scoring of the OST, and presumably related to allusive thinking as measured by Lovibond's method of scoring the OST. The possibility seems worthy of investigation that a relationship exists between a cognitive style related to conceptual, rather than behavioural, overinclusion and less efficient performance on dichotic listening tasks.
THE PRESENT STUDY A battery of tests, including the OST, WHT, WST, and dichotic listening tasks was administered to a group of 63 university students by one of the authors (M.S. A.), the OST being administered last. Details of the subjects and the administration and scoring of the OST, WHT and WST have been previously reported (Armstrong & McConaghy, 1977). All subjects completed a brief clinical test of hearing before proceeding with the dichotic listening tasks. It was predicted that subjects who obtained scores on the OST indicative of allusive thinking would show significantly more errors in shadowing performance than non-allusive thinkers. METHOD Dichotic listening tasks The procedure was adapted from Wishner & Wahl (1974). There were 5 experimental conditions. (1) Shadowing without distraction (SWOD). The subject was required to repeat aloud, as he heard them, a list of words delivered binaurally at a rate of 50 words per minute (w.p.m.). The remaining conditions all involved shadowing with distraction at slow (25 w.p.m.) or fast (50 w.p.m.) rates of presentation with induction of a simple or compound mental set. These conditions are summarized below: (2) Simple set with slow rate of presentation (SI). The subject is asked to repeat aloud words delivered through the right ear while ignoring those delivered through the left ear. (3) Compound set with slow rate of presentation (S2). The subject is asked to repeat aloud words delivered through the right ear but at the same time to try and attend to rather than ignore words delivered to the left ear. (4) Simple set with fast rate of presentation (Fl). This condition is similar to SI, except that a fast rate of presentation is employed. (5) Compound set with fast rate of presentation (F2). This condition, similar to S2 except that a fast rate of presentation is employed, was added to the procedure of Wishner & Wahl to provide an extra degree of difficulty for normal subjects. In addition to the above 5 tasks subjects also
Dichotic listening and allusive thinking
completed a dichotic word test designed by Quinn (1972, 1975) to test for cerebral dominance. Preparation of dichotic tape
The conventional technique using an electronic metronome was employed. Material for the 2 channels was recorded utilizing Revox tape recorders, with the same male voice on both channels, and later combined on a third tape recorder. Care was taken to match the amplitude of the 2 channels by monitoring VU meters during recording. Polygraphic recordings showed that 84 % of dichotic word pairs were synchronized as to onset within 65 ms (mean 37-3 ms). Presentation rates corresponded to a mean interpair interval of 855 ms under fast conditions and 2104 ms under slow conditions. The interpair interval is the interval between the beginning of one pair and the end of the preceding pair, the duration of a pair being denned by the duration of the longer item of that pair.
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made familiar with the equipment by listening to initial instructions through the headphones. Instructions were given for each condition as previously outlined. Following each of conditions 2-5, subjects were asked to recall as many D-words as they could and then as many S-words as they could. The recall task was followed each time by an auditory recognition task. This consisted of a binaural recording of the 7 S-words embedded at random in a list of 14 other words. In SWOD the 14 words were all control words (C-words), that is words not previously heard. In the other conditions, 7 of the 14 were C-words, and 7 were the D-words just presented. Subjects were asked to repeat aloud from the list, which was delivered at 25 w.p.m., those words which they recognized as words just shadowed. All responses were recorded by M.S.A. on an answer sheet which listed the complete protocol for each condition. After condition S2, subjects were given a 15-minute break during which they completed an unrelated task. Measures
Materials The words used in the shadowing with distraction conditions of the experiment were all Thorndike-Lorge AA words, that is words used more frequently than 100 times in a million in the samples of language investigated by Thorndike & Lorge (1944). For each condition words were balanced as to 'concreteness' and 'meaningfulness' between shadow, distractor and control lists as these variables have been shown to be important in perceptual and learning processes (Paivio et al. 1968). Words used in the shadowing without distraction and slow conditions were of 2 syllables; those in fast conditions were of one syllable. In each condition the words to be shadowed (S-words) consisted of a list of 7 words repeated 6 times in random order. The distractor words (D-words) consisted of a list of 7 words repeated 6 times in the same order. Presentation condition
A TEAC A-2300-S two-channel tape deck delivered the verbal material through a pair of Superex ST-V stereo headphones. Subjects were
The following scores were derived from each individual record. Shadowing errors were the total number of errors made in shadowing. These included failures of response, incorrect response and reporting of whole or part of distractor words. Where an incorrect response closely approximated the correct response (e.g. ' buddy' instead of 'body') one-half of one error was counted. Recall errors included recall of S-words as D-words and vice versa, and recall of words not presented to the subject. The recall data were also scored employing a second method. D-recall was the number of D-words recalled in each condition irrespective of whether they had been identified as D or S. Similarly S-recall referred to S-words recalled, irrespective of their identification as D or S. D-recognition and C-recognition errors were scored in the recognition tasks. These were respectively the number of D- and of C-words erroneously identified as S-words. An index of cerebral laterality was derived for each subject. The number of words correctly recalled from each ear in the Quinn Dichotic Word Test (Quinn, 1972, 1975) was determined. The index was then calculated for each individual PSM S
M. S. Armstrong, A. P. Blaszczynski and N. McConaghy
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Table 1. Summary of results for shadowing, recognition and recall data for 63 subjects
51 - total shadowing errors 52 - total shadowing errors Fl - total shadowing errors F2 - total shadowing errors Recall errors - all conditions (RCU C-recognition errors all conditions (CREC) D-recognition errors all conditions (DREC)
Mean
S.D.
Range
Correlation with OST score
2-51
2-28
0-10
015
2-24
2-45
0-12
017
6-57
5-40
0-26
0-28*
7-29
4-86
0-24
004
4-38
3-29
0-16
—
0-65
1-46
0-9
—
Factor 1
Factor 2
—
0-6075 0-7599 0-8492 0-7971 01667 00942 -00473
01432 01523 -00274 -00240 0-8519 0-7920 0-8838
3-67
310
0-15
* P < 005.
Table 2. Correlation matrix for shadowing, recognition and recall data si SI S2 Fl
F2 RCL
CREC DREC
S2
Fl
F2
RCL
CREC
— — 008 004 004
— — — 0-51 0-66
— — — — 0-56
—
0-30 0-43 0-27 0-26 011 004
Table 3. Factor matrix of data from Table 2 using principal factor without iterations
0-50 0-52 0-23 017 010
— 0-57 011 012 -007
using the formula (R —L)/(R + L) where R and L are the numbers of words recalled from right and left ears respectively. The index ranges from + 1 for complete right dominance to - 1 for complete left dominance. RESULTS No significant association was found between the index of cerebral laterality and OST score (r = 0-14, NS). Shadowing, recall, and recognition errors A summary of results on these measures is given in Tables 1 and 2. For brevity of presentation the recall and recognition errors have been summed across all conditions. (A linear combination of variables was able to account for
SI S2 Fl F2 RCL CREC DREC
Factor 1
Factor 2
0-5661 0-6915 0-6507 0-6118 0-6576 0-5636 0-5090
-0-2629 -0-3499 -0-5464 -0-5115 0-5667 0-5644 0-7240
Table 4. Factor matrix after Varimax rotation with Kaiser normalization of data from Table 2
SI S2
Fl F2 RCL CREC DREC
41-7 % of the variance in the case of recall errors and 51-7 % in the case of erroneous recognition of distractor words.) To investigate the relationship between allusive thinking and the various measures of auditory perception, the data in Table 2 were reduced by performing a principal components analysis (Nie et al. 1975). The factor matrix obtained is given in Table 3. Factor scores on the general first factor were found to be highly significantly related to OST score (r = 044, P < 0001). Inspection of the intercorrelations between different errors on the dichotic listening tasks (Table 2) suggested that measures concerned with shadowing performance and memory (recognition and recall) were relatively independent. Advantage was taken of a Varimax rotation to isolate the effects of these two groups of measures. The factor matrix after rotation is given in Table 4. The correlations of factor scores with OST score were: factor 1, r = 0-19, NS; factor 2, r = 0-47, P < 0-001. As factor 2 in the Varimax rotation reflects memory for the dichotically presented words it is possible that the relationship between OST score and factor 2 could be determined by some difference in learning or remembering ability on the part of the allusive thinkers. One aspect of
Dichotic listening and allusive thinking
such ability is reflected in the number of S- and D-words actually remembered (irrespective of whether they are correctly identified as S- or D-words). Neither recall of S-words nor recall of D-words showed any significant relationship with OST score. (The correlation of OST score with recall of S-words was r = - 0 0 8 , NS. That of recall of D-words under the individual conditions was as follows: SI, r = -0-19; S2, r = - 0 1 6 ; Fl, r = - 0 0 4 ; F2, r = 0 1 1 ; all NS.) Nature of shadowing errors
Shadowing errors consisted largely of omissions and misperceptions. Only 17-4% of shadowing errors consisted of ' interpenetrations' of Dwords. DISCUSSION The results indicate the presence of a relationship between allusive thinking and impaired performance on a dichotic listening task. Allusive thinking and shadowing performance
There was a trend for impaired shadowing performance to be associated with allusive thinking. In only 1 of the 4 shadowing with distraction conditions (Fl) did this trend reach statistical significance (r = 0-28, P < 005). In a study of 24 'high-creative' and 24 'lowcreative' university students selected on the basis of scores on the Wallach & Kogan (1965) tests of creative thinking, Dykes & McGhie (1976) demonstrated differences in shadowing performance between the 2 groups on a dichotic listening task analogous to that used in the present study. In Dykes & McGhie's study both groups of students completed the Lovibond OST, the high-creative students obtaining a mean score of 23-7 (range 13-40) and the lowcreative students a mean score of 2-4 (range 0-6). On the dichotic listening task the highcreative students made significantly more errors in shadowing than the low-creative students under conditions in which there was a strong associative connection between words in S-D pairs. If there is a relationship between allusive thinking and impaired shadowing performance,
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it seems possible that it may be manifest only when mental processes are strained. In the present study a relationship between impaired shadowing performance and allusive thinking was found under condition Fl (significantly more difficult than SI and S2) but not under F2, which is of a similar degree of difficulty to Fl in terms of the number of shadowing errors made (Table 1). Work on the WHT and WST (Armstrong & McConaghy, 1977) suggests a possible explanation for the occurrence of shadowing errors in allusive thinkers in Dykes & McGhie's strong, but not weak, associative condition. Moray (1959) noted the tendency of subjects to hear their own name in a dichotic listening task even when it was presented to the unattended ear. Information from the unattended ear is attenuated but may reach awareness if the threshold for the information is low (Treisman, 1960; Broadbent, 1970). In Dykes & McGhie's study the word presented to the attended ear could be expected to excite neural linkages associated with that word concept, so producing a lowering of threshold for the excitation of closely associated word concepts. In allusive thinkers, owing to their broader attentional process, the lowered threshold is more likely to extend to the strongly associated words delivered to the unattended ear. These words may reach consciousness and act as strong competing response tendencies, thus increasing the probability of occurrence of shadowing errors. Allusive thinking and misperception of stimulus words
If the relationship between allusive thinking and shadowing performance suggested by the present study proves replicable, it would appear that, at least under conditions of perceptual rivalry, allusive thinkers misperceive more auditorily presented words than do non-allusive thinkers. Moon et al. (1968) provided evidence that misperception of stimulus words in a word association task was significantly commoner in a group of 20 thought-disordered schizophrenics than in a group of normal controls matched on variables which included age, intelligence and auditory acuity. Moon et al. argued that such auditory misperceptions may account for many, 8-2
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M. S. Armstrong, A. P. Blaszczymki and N. McConaghy
although not all, idiosyncratic associations to stimulus words. Results with the Word Halo Test and Word Sorting Test (Armstrong & McConaghy, 1977; Tucker, 1977) provided evidence that allusive thinkers show more distant associative responses in situations where the stimulus words are presented visually so that auditory misperception was not in question. Recall and recognition data Highly significant differences were found between allusive and non-allusive thinkers when aspects of the dichotic listening task dependent on memory were examined. On the Varimax rotation, factor 2 was highly significantly related to OST score. The major part of the variance shared by OST performance scores and factor 2 was accounted for by errors in recognition and recall rather than by errors in shadowing performance. A significant proportion of these errors was due to mislabelling of D-words as S-words and vice versa. Two hypotheses could account for this mislabelling shown maximally by allusive thinkers. A peripheral filtering deficit could lead to inappropriate inclusion of D-words in the SI and Fl conditions. ('Filtering' in the present sense refers to the attentuation of information presented to the non-attended ear which thus fails to reach conscious awareness.) If this hypothesis were correct it would be expected that shadowing performance, which offers the most direct information about instantaneous attentional processes, would be particularly impaired in allusive thinkers in those conditions where filtering was required (SI, Fl) as compared with those where it was not (S2, F2). Though a significant relationship between shadowing performance and OST was found in condition Fl, performance on Fl as compared with F2 and SI as compared with S2 did not differ significantly. Furthermore, if mislabelling were a result of a hypothesized peripheral filtering deficit, subjects with this deficit should recall a greater number of D-words (D-recall) in those conditions where filtering was required. D-recall was not significantly associated with OST score in either SI (r = -0-19) or Fl (r = 0-04). The second hypothesis accounting for the mislabelling of S- and D-words relates to an
alteration of central processing in the encoding and/or retrieval of the words. The experimental situation represents a learning task with two levels: the first level involves learning which words have been presented; the second level involves learning which group (S or D) words have been presented in. Allusive and nonallusive thinkers do not differ in respect of the first level as judged by the number of S-words recalled in shadowing with or without distraction. However, in relation to the second level, failure of allusive thinkers to learn which group words belong to could account for the observed relationship. Impairment of discrimination learning is one consequence predicted by a theory relating allusive thinking to weak central inhibition (Lovibond, 1954). Payne et al. (1959) suggested that overinclusive thinking in schizophrenics could be due to defective discrimination learning. In addition to recall errors and D-recognition errors the third variable significantly contributing to the rotated factor 2 was C-recognition errors, the recognition of control words (that is words not previously presented) as S-words. Unless it is replicated in a further study, it seems unwise to attach significance to this relationship. Only one-third of the subjects included any control words, and the major part of the relationship to allusive thinking appeared to depend on high C-recognition scores obtained by the 2 highest scorers on the OST. CONCLUSIONS The results of this study support the hypothesis that allusive thinking is produced by a Pavlovian weakness of central inhibition. There was a trend for allusive thinkers to show impaired shadowing performance. Confronted simultaneously with 2 competing response tendencies, allusive thinkers show greater difficulty than non-allusive thinkers in attending to the one while excluding the other. This finding, which appears to be determined by an alteration in processing at a central rather than a peripheral level, is consistent with the notion advanced by McConaghy (McConaghy, 1974; Armstrong & McConaghy, 1977) that allusive thinkers have a broader, less sharply focused attentional process.
Dichotic listening and allusive thinking
More powerful evidence in support of a hypothesis of weak central inhibition is the finding of a strong relationship between allusive thinking and impaired discrimination learning, as demonstrated by mislabelling of S- and D-words. This project was supported by the National Health and Medical Research Council of Australia and was made possible by the appointment of the first author as a Research Fellow of the NSW Institute of Psychiatry. The help of Ken Norcross, Peter Tucker and Dr Peter Quinn and the statistical advice of Megan Neilson are gratefully acknowledged.
REFERENCES Armstrong, M. S. & McConaghy, N. (1977). Allusive thinking, the Word Halo, and verbosity. Psychological Medicine 7, 439-445. Barr, R. F. & McConaghy, N. (1972). Conditioning in relation to conceptual thinking. British Journal of Psychiatry 121, 299-310. Broadbent, D. E. (1970). Stimulus set and response set: two kinds of selective attention. In Attention: Contemporary Theories and Analysis (ed. D. Mostofsky), pp. 51-60. Appleton-Century-Crofts: New York. Dykes, M. & McGhie, A. (1976). A comparative study of attentional strategies of schizophrenic and highly creative normal subjects. British Journal of Psychiatry 128, 50-56. Harrow, M., Himmelhoch, J., Tucker, G., Hersh, J. & Quinlan, D. (1972). Overinclusive thinking in acute schizophrenic patients. Journal of Abnormal Psychology 79, 161-168. Lovibond, S. H. (1954). The object sorting test and conceptual thinking in schizophrenia. Australian Journal of Psychology 6, 52-70. Lovibond, S. H. (1966). Interim Manual for the Object Sorting Scales. Australian Council for Educational Research: Melbourne. McConaghy, N. (1960). Modes of abstract thinking and psychosis. American Journal of Psychiatry 117, 106-110. McConaghy, N. (1961). The measurement of an inhibitory process in human higher nervous activity: its relation to allusive thinking and fatigue. American Journal of Psychiatry 118, 125-132. McConaghy, N. (1974). Allusive thinking and the ocular angle alpha. In Essays on Schizophrenia Essay no. 7. Ethnor Ltd: Sydney.
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McConaghy, N. & Clancy, M. (1968). Familial relationships of allusive thinking in university students and their parents. British Journal of Psychiatry 114, 1079-1087. Moon, A. F., MefTerd, R. B., Jr, Wieland, B. A., Pokorny, A. D. & Falconer, G. A. (1968). Perceptual dysfunction as a determinant of schizophrenic word associations. Journal of Nervous and Mental Disease 146, 80-84. Moray, N. (1959). Attention in dichotic listening: affective cues and the influence of instructions. Quarterly Journal of Experimental Psychology 11, 56-60. Nie, N. H., Hull, C. H., Jenkins, J. G., Steinbrenner, K. & Bent, D. H. (1975). Statistical'Package for the Social Sciences. McGraw-Hill: New York. Paivio, A., Yuille, J. C. & Madigan, S. A. (1968). Concreteness, imagery, and meaningfullness values for 925 nouns. Journal of Experimental Psychology Monograph Supplement, 76, no. 1, part 2, 1-25. Payne, R. (1973). Cognitive abnormalities. In Handbook of Abnormal Psychology (ed. H. J. Eysenck), pp. 420-483. Pitman: London. Payne, R. & Friedlander, D. (1962). A short battery of simple tests for measuring overinclusive thinking. Journal of Mental Science 108, 362-367. Payne, R., Matussek, P. & George, E. I. (1959). An experimental study of schizophrenic thought disorder. Journal of Mental Science 105, 627-652. Payne, R., Hochberg, A. C. & Hawks, D. V. (1970). Dichotic stimulation as a method of assessing the disorder of attention in overinclusive schizophrenic patients. Journal of Abnormal Psychology 76, 185-193. Quinn, P. T. (1972). Stuttering: cerebral dominance and the dichotic word test. Medical Journal of Australia 2, 639-643. Quinn, P. T. (1975). The investigation of neurological factors in stutterers. Unpublished Ph.D. Thesis, University of New South Wales. Rosman, B., Wild, C , Ricci, J., Fleck, S. & Lidz, T. (1964). Thought disorder in the parents of schizophrenic patients: a further study utilizing the object sorting test. Journal of Psychiatric Research 2, 211-221. Thorndike, E. L. & Lorge, I. (1944). The Teacher's Wordbook o/30000 Words. Teachers College, Bureau of Publications: New York. Treisman, A. M. (I960). Contextual cues in selective listening. Quarterly Journal of Experimental Psychology 12, 242-248. Tucker, P. K. (1977). Allusive thinking and creativity in high school students. Unpublished B.Sc (Med.) thesis, University of New South Wales. Wallach, M. A. & Kogan, N. (1965). Modes of Thinking in Young Children: A Study of the Creativity-Intelligence Distinction. Holt, Rinehart and Winston: New York. Wishner, J. & Wahl, O. (1974). Dichotic listening in schizophrenia. Journal of Consulting and Clinical Psychology 42, 538-546.
