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Comment on “A Factor Analytic Study of Two Scales Measuring Dissociation” by Fischer and Elnitsky a
Eve Bernstein Carlson & Frank W. Putnam a
b
Beloit College , Beloit, WI, USA
b
Unit on Dissociative Disorders National Institute of Mental Health , USA Published online: 21 Sep 2011.
To cite this article: Eve Bernstein Carlson & Frank W. Putnam (1990) Comment on “A Factor Analytic Study of Two Scales Measuring Dissociation” by Fischer and Elnitsky, American Journal of Clinical Hypnosis, 33:2, 133-134, DOI: 10.1080/00029157.1990.10402918 To link to this article: http://dx.doi.org/10.1080/00029157.1990.10402918
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
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AMERICAN JOURNAL OF CLINICAL HYPNOSIS
VOLUME
33, NUMBER
2, DeroBER 1990
Letters to the Editor
Downloaded by [Australian National University] at 23:53 13 March 2015
Comment on "A Factor Analytic Study of Two Scales Measuring Dissociation" by Fischer and Elnitsky We were puzzled by some aspects of the recent American Journal of Clinical Hypnosis article by Fischer and Elnitsky (1990) entitled "A Factor Analytic Study of Two Scales Measuring Dissociation." We feel there are a number of significant problems in the logic and design of the study that limit its conclusions. Fischer and Elnitsky state that the purpose of their study was to compare the internal structure of the two dissociation scales using a normal population. They then state: "Results will have theoretical value by providing evidence of construct validity and also clinical significance by offering a more precise screening device to clinicians." (Fischer & Elnitsky, 1990, p. 202). How can this be? How can studying the structure of an instrument using the responses of subjects in a normal population provide any evidence pertinent to its use for screening in clinical populations? We agree completely with the authors' statement that "it may be that different factor structures are necessary to represent pathological populations" (p. 206). We have found that normal and clinicalsamples produce very different item and total scores on the DES (Bernstein & Putnam, 1986), and these findings have been replicated by several different in-
vestigators (e.g., Coons, Bowman, & Milstein, 1988; Ross, Norton, & Anderson, 1988; Sanders, McRoberts, & Tollefson, 1989). Secondly, the conclusion that the DES does not reliably measure "the three dimensions hypothesized to underlie dissociative experience in a normal college population" is meaningless. Why should there be any expectation that the factors hypothesized by one author for her own instrument (the PAS) would be found to underlie another scale (the DES) by authors who did not hypothesize the factors? This presupposes that the PAS is a valid measure of the construct of dissociation and that the proposed hypothesis was correct. We would argue that the validity of the PAS and this particular hypothesis have not yet been established and should not be used as standards for the DES to match. In addition, the study did not use the original version of the DES. The Instruments section of the Fischer and Elnitsky article describes subjects using a 10-point scale. As stated in our original report on the DES, "our response format consists of a 100-mm line with no divisions and numerically anchored at the endpoints" (Bernstein & Putnam, 1986, p. 729). Items are scored by measuring from the lefthand anchor point to the subject's slash mark to the nearest 5 mm. We are not sure of the impact of this change in the response scale, but believe that it is un-
133
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134
LETfERS TO THE EDITOR
wise to assume that the change will have no effect; it is certainly misleading to make no mention of the change in the article. Finally, the article suggests adding more affect and control items to the DES "in an attempt to identify the hypothesized three dimensions" (Fischer & Elnitsky, 1990, p. 206). We do not agree that it is desirable to model the DES on the hypotheses of the PAS. Furthermore, our exclusion of affect items on the DES was intentional. As stated in our original descriptive article, "items identifying dissociation of moods and impulses were excluded from the scale so that experiences of dissociation would not be confused with alterations in mood and impulse associated with affective disorders" (Bernstein & Putnam, 1986, p. 729). References
Bernstein, E. M. & Putnam, F. W. (1986). Development, reliability, and validity of a dissociation scale. Journal of Nervous and Mental Disease, 174, 727-735.
Coons, P. M., Bowman, E. S., & Milstein, V. (1988). Multiple personality disorder: A clinical investigation of 50 cases. Journal of Nervous and Mental Disease, 176, 519527. Fischer, D. G. & Elnitsky, S. (1990). A factor
analytic study of two scales measuring dissociation. American Journal of Clinical Hypnosis, 32,201-207.
Ross, C., Norton, G. R., & Anderson, B. (1988). The Dissociative Experiences Scale: A replication study. Dissociation, 1(3),2122.
Sanders, B., McRoberts, B. & Tollefson, C. (1989). Childhood stressand dissociation in a college population. Dissociation, 2(1), 1723.
Eve Bernstein Carlson Assistant Professor Beloit College Beloit, Wl
w:
Frank Putnam Chief Unit on Dissociative Disorders National Institute of Mental Health
Reply to Carlson and Putnam letter
1. Carlson and Putnam take issue with our statement: "Results will have theoretical value by providing evidence of construct validity and also clinical significance by offering a more precise screening device to clinicians." They note "How can this be? How can studying the structure of an instrument using the responses of subjects in a normal population provide any evidence pertinent to its use for screening in clinical populations?" We think it is important to study the factor structure of the DES in the normal population (particularly adolescents), if it is going to be used for comparison purposes, as it was in Bernstein and Putnam's (1986) reliability and validity analysis. We believe that clinicians also will want to know how different their pathological group/client is from other groups, both pathological and normal. Bernstein and Putnam (1986) in their comparison of pathological groups with normals report that there is " ... a steady progression in the median DES scores from normal subjects to multiple personality patients," and show in Figure 1 of their paper the median scores, in increasing order of dissociation, for normals, alcoholics, phobic anxiety, agoraphobics, adolescents, schizophrenics, posttraumatic stress disorder, and multiple personality disorder patients. It is interesting to note that adolescents had higher DES scores than normal adults, alcoholics, phobics, and agoraphobics and lower
American Journal of Clinical Hypnosis Publication details, including instructions for authors and subscription information: http://www.tandfonline.com/loi/ujhy20
Comment on “A Factor Analytic Study of Two Scales Measuring Dissociation” by Fischer and Elnitsky a
Eve Bernstein Carlson & Frank W. Putnam a
b
Beloit College , Beloit, WI, USA
b
Unit on Dissociative Disorders National Institute of Mental Health , USA Published online: 21 Sep 2011.
To cite this article: Eve Bernstein Carlson & Frank W. Putnam (1990) Comment on “A Factor Analytic Study of Two Scales Measuring Dissociation” by Fischer and Elnitsky, American Journal of Clinical Hypnosis, 33:2, 133-134, DOI: 10.1080/00029157.1990.10402918 To link to this article: http://dx.doi.org/10.1080/00029157.1990.10402918
PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden.
Downloaded by [Australian National University] at 23:53 13 March 2015
Terms & Conditions of access and use can be found at http://www.tandfonline.com/ page/terms-and-conditions
AMERICAN JOURNAL OF CLINICAL HYPNOSIS
VOLUME
33, NUMBER
2, DeroBER 1990
Letters to the Editor
Downloaded by [Australian National University] at 23:53 13 March 2015
Comment on "A Factor Analytic Study of Two Scales Measuring Dissociation" by Fischer and Elnitsky We were puzzled by some aspects of the recent American Journal of Clinical Hypnosis article by Fischer and Elnitsky (1990) entitled "A Factor Analytic Study of Two Scales Measuring Dissociation." We feel there are a number of significant problems in the logic and design of the study that limit its conclusions. Fischer and Elnitsky state that the purpose of their study was to compare the internal structure of the two dissociation scales using a normal population. They then state: "Results will have theoretical value by providing evidence of construct validity and also clinical significance by offering a more precise screening device to clinicians." (Fischer & Elnitsky, 1990, p. 202). How can this be? How can studying the structure of an instrument using the responses of subjects in a normal population provide any evidence pertinent to its use for screening in clinical populations? We agree completely with the authors' statement that "it may be that different factor structures are necessary to represent pathological populations" (p. 206). We have found that normal and clinicalsamples produce very different item and total scores on the DES (Bernstein & Putnam, 1986), and these findings have been replicated by several different in-
vestigators (e.g., Coons, Bowman, & Milstein, 1988; Ross, Norton, & Anderson, 1988; Sanders, McRoberts, & Tollefson, 1989). Secondly, the conclusion that the DES does not reliably measure "the three dimensions hypothesized to underlie dissociative experience in a normal college population" is meaningless. Why should there be any expectation that the factors hypothesized by one author for her own instrument (the PAS) would be found to underlie another scale (the DES) by authors who did not hypothesize the factors? This presupposes that the PAS is a valid measure of the construct of dissociation and that the proposed hypothesis was correct. We would argue that the validity of the PAS and this particular hypothesis have not yet been established and should not be used as standards for the DES to match. In addition, the study did not use the original version of the DES. The Instruments section of the Fischer and Elnitsky article describes subjects using a 10-point scale. As stated in our original report on the DES, "our response format consists of a 100-mm line with no divisions and numerically anchored at the endpoints" (Bernstein & Putnam, 1986, p. 729). Items are scored by measuring from the lefthand anchor point to the subject's slash mark to the nearest 5 mm. We are not sure of the impact of this change in the response scale, but believe that it is un-
133
Downloaded by [Australian National University] at 23:53 13 March 2015
134
LETfERS TO THE EDITOR
wise to assume that the change will have no effect; it is certainly misleading to make no mention of the change in the article. Finally, the article suggests adding more affect and control items to the DES "in an attempt to identify the hypothesized three dimensions" (Fischer & Elnitsky, 1990, p. 206). We do not agree that it is desirable to model the DES on the hypotheses of the PAS. Furthermore, our exclusion of affect items on the DES was intentional. As stated in our original descriptive article, "items identifying dissociation of moods and impulses were excluded from the scale so that experiences of dissociation would not be confused with alterations in mood and impulse associated with affective disorders" (Bernstein & Putnam, 1986, p. 729). References
Bernstein, E. M. & Putnam, F. W. (1986). Development, reliability, and validity of a dissociation scale. Journal of Nervous and Mental Disease, 174, 727-735.
Coons, P. M., Bowman, E. S., & Milstein, V. (1988). Multiple personality disorder: A clinical investigation of 50 cases. Journal of Nervous and Mental Disease, 176, 519527. Fischer, D. G. & Elnitsky, S. (1990). A factor
analytic study of two scales measuring dissociation. American Journal of Clinical Hypnosis, 32,201-207.
Ross, C., Norton, G. R., & Anderson, B. (1988). The Dissociative Experiences Scale: A replication study. Dissociation, 1(3),2122.
Sanders, B., McRoberts, B. & Tollefson, C. (1989). Childhood stressand dissociation in a college population. Dissociation, 2(1), 1723.
Eve Bernstein Carlson Assistant Professor Beloit College Beloit, Wl
w:
Frank Putnam Chief Unit on Dissociative Disorders National Institute of Mental Health
Reply to Carlson and Putnam letter
1. Carlson and Putnam take issue with our statement: "Results will have theoretical value by providing evidence of construct validity and also clinical significance by offering a more precise screening device to clinicians." They note "How can this be? How can studying the structure of an instrument using the responses of subjects in a normal population provide any evidence pertinent to its use for screening in clinical populations?" We think it is important to study the factor structure of the DES in the normal population (particularly adolescents), if it is going to be used for comparison purposes, as it was in Bernstein and Putnam's (1986) reliability and validity analysis. We believe that clinicians also will want to know how different their pathological group/client is from other groups, both pathological and normal. Bernstein and Putnam (1986) in their comparison of pathological groups with normals report that there is " ... a steady progression in the median DES scores from normal subjects to multiple personality patients," and show in Figure 1 of their paper the median scores, in increasing order of dissociation, for normals, alcoholics, phobic anxiety, agoraphobics, adolescents, schizophrenics, posttraumatic stress disorder, and multiple personality disorder patients. It is interesting to note that adolescents had higher DES scores than normal adults, alcoholics, phobics, and agoraphobics and lower
