The Object-Sorting Test asa Differential Diagnostic Tool Patrick J. Collins. Cathy Clark, Baron Shopsin, George Sakalis, and Gregory Sathananthan

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PSYCHOPHARMACOLOGY h a s u n d e r l i n e d t h e n e e d for d i a g n o s t i c specificity in t h e effort to achieve a g r e a t e r d e g r e e o f t h e r a p e u t i c specificity. F o r e x a m p l e , the use o f the l i t h i u m ion in p s y c h i a t r y h a s r e o p e n e d o n e o f the fun, d a m e n t a l and often bewildering e n i g m a s in c l i n i c a l : p s y c h i a t r y ~ t h e differential diagnosis between m a n i c , depressive illness a n d schizophrenia. P r o p e r diagnosis is a p p a r e n t l y c e n t r a l to achieving s u c c e s s with .|ithium in t h a t m a n i c p a t i e n t s with m o r e n e a r l y p u r e o r typical s y m p t o m s a p p e a r to r e s p o n d best to this m e d i c a t i o n , while a s m o r e a t y p i c a l " ' s c h i z o p h r e n i c " f e a t u r e s e n c r o a c h on the affeetive .portion, s u c c e s s with lithium diminishes. In f a c t , : s o m e r e p o r t s indicate t h a t schizophrenic p a t i e n t s , i r r e s p e c t i v e o f t h e affective overlay, d o p o o r l y with lithium, showing an a g g r a v a t i o n o f p s y c h o p a t h o l o g y a n d n e u r o t o x i c p h e n o m e n a . T o d a t e , m o s t e f f o r t s - h a v e n o t -been a b l e to find an infallible c r i t e r i o n t h a t differentiates the affective and the s c h i z o p h r e n i c d i s o r d e r s . O u r d e p a r t m e n t h a s been i n t e r e s t e d in this p r o b l e m o f differential diagnosis o f the affective illnesses b e c a u s e o f e a r l y findings o f ~ t h e r a p e u t i c specificity with lithium. In an ongoing a t t e m p t to define m a n i a and s c h i z o p h r e n i a m o r e clearly, we h a v e c e n t e r e d o u r a t t e n t i o n on t h e m e a s u r e m e n t ,of t h o u g h t d i s o r d e r , widely considered as-pathognomonic o f s c h i z o p h r e n i a - Since Bleuler's notion o f " l o o s e n i n g in t h e a s s o c i a t i o n o f ideas. ''2 In clinical p r a c t i c e , differential diagnosis b a s e d on the p r e s e n c e o f t h o u g h t d i s o r d e r is c o m p l i c a t e d by t h e v a r i e t y o f s y m p t o m c o m p l e x e s in schizophrenia. F o r e x a m p l e , n o t all s c h i z o p h r e n i c s exhibit t h o u g h t d i s o r d e r ; in f a c t , t h o u g h t - d i s o r d e r e d s c h i z o p h r e n i c s a r e o f t e n c o n s i d e r e d a s u b g r o u p , a F u r t h e r m o r e , s o m e f o r m o f t h o u g h t d i s o r d e r h a s also been r e p o r t e d in the affective p s y c h o s e s ; in both u n i p o l a r and bipo[ar d e p r e s s i o n , a n d in m a n i c s t a t e s . 4--e l a n z i t o et al. suggested t h a t t h o u g h t d i s o r d e r in d e p r e s s i o n m a y predict a m o r e severe episode and p e r h a p s should be c o n s i d e r e d a s u b g r o u p o f d e p r e s s i o n , a n a l o g o u s to schizophrenic s u b g r o u p s . Thi~se s t u d i e s s u g g e s t a t l e a s t two possibilities; (1) t h o u g h t d i s o r d e r is f r e q u e n t l y p r e s e n t in b o t h s c h i z o p h r e n i a and haania1~md i s t h e r e f o r e - n o t useful for differential diagnosis; (2) t h e r e is a m a j o r d i s a g r e e m e n t a m o n g i n v e s t i g a t o r s as to w h a t c o n s t i t u t e s t h o u g h t d i s o r d e r .

From the Neuropsychopharmacology. Research Unit,-Departmentof:Psychiatry, New York University ffchool o f Medicine, New York, N. Y. Patrick J . C o l l i n s , Ph.D.: Assistant-Research Sc.ientist;.~Cathy_ P. C l a r k , - B.A.: Assistant Psychologist; Baron Shopsin, M.D.: Associate Professor o f Psychiat~'y:-George Sakalis, M.D., D.P.M.: Assistant Professor o f Psychiatry: Grrgor2¢ S a t h a n a n t h a n r M.D., D.P.M.: Assistant Professor o f Psychiatry, Neuropsychopharmacology Research Unit. Department o f Psychiatry, New York University School o f Medicine. Supported by U S P H S grant M H 04669. © 1975 by Grune & Stratton, Inc.

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In the s t u d y r e p o r t e d here we m a k e a f u r t h e r a t t e m p t to clarify the issue by objectively m e a s u r i n g the degree of t h o u g h t d i s o r d e r p r e s e n t in both inpatient and o u t p a t i e n t p o p u l a t i o n s in our N e u r o p s y c h o p h a r m a c o l o g y R e s e a r c h Unit, N e w Y o r k U n i v e r s i t y - B e l l e v u e H o s p i t a l C e n t e r , using a s o r t i n g test. F u r t h e r m o r e , clinical ratings o f both f o r m a l and content t h o u g h t d i s o r d e r were obtained whenever possible using the Brief P s y c h i a t r i c R a t i n g S c a l e ( B P R S ) . O u r diagnostic criteria were those used by Feighner et al. 4 and lanzito et al., ° with the exception t h a t for a diagnosis o f M a n i c - D e p r e s s i v e , D e p r e s s e d , we required ( ! ) chronic a n h e d o n i a , (2) functional i n c a p a c i t y , and (3) c o n s t a n t fatigue. SORTING TEST

T h e G o l d s t e i n - S c h e e r e r object-sorting test was chosen as o u r m e a s u r e because of its direct t h e o r e t i c a l connections with C a m e r o n ' s c o n c e p t o f overinclusive thinking, 7.~ which is often considered c e n t r a l to schizophrenic t h o u g h t disorder. Overinclusive thinking was defined by C a m e r o n as an "'inability to p r e s e r v e conceptual b o u n d a r i e s " - - e . g . , on a sorting test t h a t required the g r o u p i n g o f everyday objects (tools, toys, utensils, e t c . ) a c c o r d i n g to a simple concept, schizophrenics were overinclusive in their s o r t s , s o m e t i m e s even including in t h e g r o u p s objects o t h e r than the test m a t e r i a l . S e v e r a l recent a t t e m p t s at differential diagnosis using objective tests have l e f t their value unclear. P a y n e et al. used a b a t t e r y of tests ( B a n n i s t e r - F r a n z e l l a grid test, the G o l d s t e i n - S c h e e r e r object-sorting test, and the Benjamin p r o v e r b s test) to derive a f a c t o r score t h a t differentiated betwe.en a c u t e schizophrenics and a n e u r o t i c control g r o u p . 9 H o w e v e r , in a m o r e recent s t u d y they failed to s u p p o r t their earlier findings using the s a m e test b a t t e r y in an a t t e m p t to predict final diagnosis of an unselected r e p r e s e n t a t i v e s a m p l e o f m e n t a l - h o s p i t a l admissions.l° In s u m m a r y , they found no significant col'relations between the tests and a failure o f overinclusive test p e r f o r m a n c e to c o r r e l a t e with final diagnosis. in a s t u d y utilizing only the object-sorting test, H a r r o w and his c o - w o r k e r s found behavioral overinclusion m o r e f r e q u e n t l y in schizophrenics, but it was also present in a c u t e n o n s c h i z o p h r e n i c s (depressives and p e r s o n a l i t y disorders). II In one of the few longitudinal studies of schizophrenic thinking using the objectsorting test, H a r r o w et al. found c o n c e p t u a l overinclusion to be c h a r a c t e r i s t i c o f a c u t e schizophrenia, but idiosyncratic thinking was m o r e unique to schizophrenia and s e e m e d to be a p e r m a n e n t c h a r a c t e r i s t i c of schizophrenic thinking. I~ U n f o r t u n a t e l y the scoring s y s t e m used by H a r r o w et al. is n o t c o m p a r a b l e to the scoring s y s t e m o f P a y n e et al., which simply r e c o r d s the n u m b e r o f o b j e c t s "'handed o v e r " in r e s p o n s e to a n u m b e r o f s t i m u l u s objects. In o u r use of the object-sorting test for this study, two s c o r e s were obtained: ( I ) P a y n e ' s h a n d i n g - o v e r score, and (2) a general i m p a i r m e n t score. T h e l a t t e r score is s o m e w h a t subjective, but includes d i m e n s i o n s o f H a r r o w ' s C o n c e p t u a l Overinclusion and I d i o s y n c r a t i c Thinking. ~s T h e m a j o r hypothesis o f the s t u d y was t h a t f o r m a l t h o u g h t d i s o r d e r would be present in the schizophrenic g r o u p s but not in the affective g r o u p s n o r in the o t h e r p s y c h i a t r i c p a t i e n t s and n o r m a l s . A subsidiary hypothesis was t h a t f o r m a l thought d i s o r d e r would be p r e p o n d e r a n t in the schizophrenic n o n p a r a n o i d g r o u p , as is usually observed clinically.

OBJECT-SORTING TEST

393 METHOD

Subjects One hundred twenty-five subjects weretested over a period of 1,4 months. These included inpatients at Bellevue Psychiatric Hospital on the Neuropsychopharmacology Research Unit and outpatients at "the Lithium Clinic of New York University Medical Center, as well as normal controls from the Bellevue and New York University Medical Centers staff. The exclusion criteria were the presence of the following: 1. 2. 3. 4.

Evidence or suspicion oforganicity. Psychosis associated with alcoholism or drug abuse. Inability to speak English. Mental retardation.

The following eight groups were to be compared: I. 2. 3. 4. 5. 6. 7. 8.

Schizophrenia r Nonparanoid type. Schizophrenia, Paranoid type. Schizophrenia. Schizo-Affective type. Manic- Depressive-Manic phase. Manic- Depressive- In terphase. Manic- Depressive- Depressed phase. Other psychiatric disorders. Normal controls. ~

Procedure The test was administered by either of two psychologists who were blind with respect to the diagnoses of the inpatients and the current mental states of the outpatients. Each psychologist tested approximately one-half of the entire sample, and the tests were scored by both psychologists. With the exception of the Manic-Depressive-lnterphase group (who were maintained on lithium carbonate), all patients were tested after a minimum of 7 days wherein they were administered only placebo medication. Clinical ratings of pathology were performed at that time by the patient's psychiatrists using the BPRS. The object-sorting test consists of 33 c o m m o n objects (real tools, toy tools, real and toy cigarettes, cigars, eating utensils, etc.). The subject is first asked if he can identify all of the objects and is then instructed to hand over to the experimenter all the objects that "'belong together," i.e., to give a reason for the sort. This is repeated six more times, with the experimenter choosing the initial object. In part two of the test the experimenter performs twelve consecutive simple sorts, e.g., all red objects, all rubber objects, all toys, all round objects, etc., and the subject is asked to explain the reason for the grouping. Two scores were calculated from the results of the test. The mean number o f objects handed over to the experimenter in response to the seven starting objects constituted the handing-over score o f overinclusion. ~'' The second score Focused on the appropriateness o f the subject's explanation and resulted in an overall impairment score for each subject. R ES U L T S T h e f i n a l s a m p l e s h o w n in T a b l e 1 c o n s i s t e d o f 105 s u b j e c t s d i s t r i b u t e d a c r o s s six g r o u p s . T w e n t y s u b j e c t s w e r e n o t i n c l u d e d in t h e d a t a a n a l y s i s b e c a u s e i t w a s recognized after testing that one or more of the exclusion criteria was present. The number of subjects per group (N), the mean age, the age range, and the e d u c a t i o n l e v e l a n d r a n g e a r e a l s o l i s t e d in T a b l e 1. A n a l y s i s o f v a r i a n c e o f s u b j e c t s ' a g e s a c r o s s t h e six g r o u p s s h o w e d a s i g n i f i c a n t difference among the groups (p < 0.001). Comparisons of the group means indicated that the Manic-Depressive-Manic and the Manic-Depressive-lnterphase groups were significantly older than each of the other groups, but showed no

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Table 1. Mean Age and Range, Education Level and Range, an d )V per G r o u p Group Normal

Schizophrenic, N o n p a r a n o i d Schizophrenic, Paranoid Other ~ Manic-Depressive-Manic M a n i c - Depressive-! n terphase

N

Mean Age

Range

Mean Education Level (yr)

Range

20 29 15 9 9 23

28.8 27.0 33.4 28.2 4g.7 55.3

18-45 19-53 25-55 27-56 37-59 31-71

13.0 10.5 11.5 10.0 12.0 12.5

9-20 7-18 8-18 7-15 10-18 9-18

* T h e diagnoses of the 1 0 patients in the " O t h e r " group were: drug abuselcharacter disorder~ alcoholic hallucinosis (2 patients); neurotic depressive reaction w i t h alcoholism; neurotic depressive reaction; alcoholism (2 patients); involutional melancholia; and psychotic depression ( 2 patients).

significant difference f r o m each other. A s e c o n d a n a l y s i s o f variance a c r o s s g r o u p s for educational level showed no significant differences. Test Results

A n a l y s i s o f covariance, with age as the covariate for the six g r o u p s , on the mean n u m b e r o f objects handed over (object score) and the i m p a i r m e n t score s h o w e d a significant F ratio for both m e a s u r e s o f the m e a n object s c o r e s and the i m p a i r m e n t scores. All possible pairwise c o m p a r i s o n s o f the g r o u p m e a n s (Table 2), using the S c h e f f e m e t h o d , s h o w e d the following relationships: A. Object scores: no significant differences between any pair o f g r o u p m e a n s . B. I m p a i r m e n t scores: d i f f e r e n c e s s i g n i f i c a n t l y greater ( p < 0.05) for: I. S c h i z o p h r e n i c Paranoid versus M a n i c - D e p r e s s i v e - l n t e r p h a s e . 2. S c h i z o p h r e n i c Paranoid versus N o r m a l s . 3. S c h i z o p h r e n i c Paranoid v e r s u s other patients. 4. S c h i z o p h r e n i c N o n p a r a n o i d versus N o r m a l s . TM F u r t h e r c o m p a r i s o n s o f interest were p e r f o r m e d with the two s c h i z o p h r e n i c g r o u p s c o m b i n e d (Table 3). For the object scores, o n e significant difference emerged: the c o m b i n e d S c h i z o p h r e n i c g r o u p had significantly higher s c o r e s than the M a n i c - D e p r e s s i v e - I n t e r p h a s e group. On the i m p a i r m e n t scores, the c o m b i n e d S c h i z o p h r e n i c g r o u p scored significantly higher than the N o r m a l g r o u p or the M a n i c - D e p r e s s i v e - l n t e r p h a s e g r o u p . In s u m m a r y , only the i m p a i r m e n t s c o r e differentiated a m o n g t h e original groups. W h e n the S c h i z o p h r e n i c g r o u p s were c o m b i n e d and c o m p a r e d with each o f the other g r o u p s , the S c h i z o p h r e n i c s were significantly higher than the N o r reals on i m p a i r m e n t s c o r e s and higher than the M a n i c - D e p r e s s i v e - l n t e r p h a s e group on both scores. Table 2. Mean Object and I m p a i r m e n t Scores f o r the Six Groups Schlzophrenic N u m b e r of subjects Object score Standard deviation ! mpairment score

Standard deviation

Manic- Depressive

Paranoid

Nonparanoid

Manic

Interphase

Normal

Other

15 8.9 8.4 19.4 15.2

29 7.2 8.3 13.5 11.8

9 5.9 4.4 8.0 4.5

23 3.1 1.5 5.8 6.7

20 4.1 1.5 2.7 2.9

9 3.0 2.6 5.1 4.8

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Table 3. Results With

N u m b e r o f subjects O b j e c t score Standard deviation I m p a i r m e n t score Standard deviation

Schizophrenic Subgroups C o m b i n e d

Schizophrenic

Manic

Interphase

Normal

Other

44 8.0 8.3 15.0 13.4

9 5.9 4.4 8.0 4.5

23 3. t 1.5 5.8 6.7

20 4.1 1.5 2.7 2.9

9 3.0 2.6 5.1 4.8

Thought Disorder--Clinical Ratings T h e clinical ratings on the Brief Psychiatric R a t i n g Scale ( B P R S ) were used to e s t i m a t e the degree o f f o r m a l and content thought disorder. 3 Fish d e s c r i b e s f o r m a l thought disorder as "'an inability to think a b s t r a c t l y in the absence of coarse brain disease.'" A subcategory, "'positive" f o r m a l thought disorder, nearly s y n o n y m o u s with "'schizophrenic thought d i s o r d e r " in the English literature, includes "'overinclusive thinking." C o n t e n t thought disorder r e f e r s m a i n l y to paranoid delusions, i.e., ideas o f selfreference, p e r s e c u t o r y delusions, and grandiose delusions, as well as hypochondriacal, guilt, and nihilistic delusions. 3 T a b l e 4 shows the e s t i m a t e s of thought disorder and the object and i m p a i r m e n t scores for four g r o u p s (the N o r m a l g r o u p was not clinically rated, and the M a n i c - D e p r e s s i v e - I n t e r p h a s e outpatients exhibited no clinically recognizable thought disorder). T h e P a r a n o i d S c h i z o p h r e n i c s had the highest ratings on both m e a s u r e s o f thought disorder. T h e scales for our e s t i m a t e s o f f o r m a l and content thought disorder are not directly c o m p a r a b l e (different n u m b e r s of i t e m s used for each estimate), which m a d e f o r m a l statistical analysis inappropriate. However, the differences were in the expected direction for the Schizophrenics, i.e., the P a r a n o i d s showed m o r e content than f o r m a l thought disorder, while the N o n p a r a n o i d s showed m o r e f o r m a l than content t h o u g h t disorder. ~-3 It was n o t e w o r t h y that both types o f thought disorder existed in each group; in fact, all but 1 patient showed both types of thought disorder. T h e Manic-Depressive-Manics showed slightly m o r e content than f o r m a l thought disorder. Also, within the N o n p a r a n o i d Schizophrenic group, the patients with the m o s t f o r m a l thought disorder had the highest I m p a i r m e n t scores.

Table 4, Clinical Ratings o f T h o u g h t Disorder:and Test Scores*

Group

Formal Thought Disorder

Content Thought Disorder

Object Score

Impairment Score

S c h i z o p h r e n i c Paranoid Schizophrenic Nonparanoid Manic-Depressive-Manic Other

3,6 3.4 1.8 1.3

4.0 3.2 2.5 1.3

8.1 7.5 5.5 2,8

16.8 13.8 6.0 4.3

* T h e BPRS ratings o f t h o u g h t disorder are based o n a seven-point rating scale: 1, n o t present; 7, e x t r e m e l y severe.

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COLLINS ET AL.

DISCUSSION

T h e s e findings suggest t h a t S c h i z o p h r e n i c s c a n n o t be d i f f e r e n t i a t e d f r o m M a n i c - D e p r e s s i v e s in the m a n i c p h a s e on the basis of P a y n e ' s h a n d i n g o v e r s c o r e n o r L o v i b o n d ' s i m p a i r m e n t s c o r e on the o b j e c t - s o r t i n g test. T h e results a r e consistent with the f r e q u e n t findings o f an o v e r l a p a m o n g d i a g n o s t i c g r o u p s on objectively m e a s u r e d and clinically r a t e d t h o u g h t d i s o r d e r - - b o t h o f the f o r m a l a n d c o n t e n t type. 4-6 T h e test scores, p a r t i c u l a r l y L o v i b o n d ' s i m p a i r m e n t score, can be m o r e r e a d i l y i n t e r p r e t e d as a reflection of severe m e n t a l d i s t u r b a n c e in the S c h i z o p h r e n i c s a n d in the M a n i c - D e p r e s s i v e - M a n i c s . A d d i t i o n a l l y , the m a g n i t u d e o f the test s c o r e s - - t h r e e t o four t i m e s higher t h a n t h e clinical r a t i n g s o f t h o u g h t d i s o r d e r - - m a y i n d i c a t e a p o t e n t i a l for the test as a m o r e sensitive ins t r u m e n t o f clinical c h a n g e o r o f d r u g response. A l t h o u g h no significant difference a m o n g s t the g r o u p s on e d u c a t i o n level e m e r g e d , t h e g e n e r a l l y l o w e r e d u c a t i o n level for the overall S c h i z o p h r e n i c g r o u p is in line with p r e v i o u s findings o f n o n s i g n i f i c a n t , but positive inverse, c o r r e l a t i o n s between educationa:, level and i m p a i r m e n t scores. ~a-~5 I n s u m m a r y , two int e r p r e t a t i o n s o f the d a t a a r e possible, a l m o s t identical t o B r e a k e y and G o o d e l l ' s s c o n c l u s i o n s c o n c e r n i n g the B a n n i s t o r grid test; either: ( 1 ) T h o u g h t d i s o r d e r as m e a s u r e d by the G o l d s t e i n - S c h e e r e r o b j e c t - s o r t i n g test is n o t significantly g r e a t e r in S c h i z o p h r e n i c s when c o m p a r e d with M a n i c - D e p r e s s i v e s in t h e m a n i c stage o f illness or (2) the objec -t~orting test does n o t m e a s u r e s.ohizophrenic t h o u g h t d i s o r d e r , b u t s o m e o t h e r f u n c t i o n a l disability or an a r t i f a c t , Le., high verbal r e s p o n s i v e n e s s , which can o c c u r in b o t h s c h i z o p h r e n i a and m a n i a . T h e f o r m e r i n t e r p r e t a t i o n s u p p o r t s S c h n e i d e r ' s c o n t e n t i o n t h a t "'However imp o r t a n t t h e s e t h o u g h t d i s o r d e r s m a y be for t h e o r e t i c a l definition o f the n a t u r e o f s c h i z o p h r e n i a , they do n o t hold m u c h weight in p r a c t i c e as d i a g n o s t i c features. "'~ C o n c e r n i n g the l a t t e r , t h e r e is evidence s u p p o r t i n g t h e h y p o t h e s i s t h a t s o m e obj e c t i v e t e s t s o f overinclusive t h i n k i n g m a y be m e a s u r i n g verbal responsiveness. P a y n e a n d Hew~ett ~z observed t h a t S c h i z o p h r e n i c s in their s t u d y who were n o t a b n o r m a l l y o v e r i n c l u s i v e suffered f r o m e x t r e m e p s y c h o m o t o r r e t a r d a t i o n . Alt h o u g h verbal responsiveness was n o t r e p o r t e d in their study, and p r e s u m a b l y was n o t m e a s u r e d , t h e r e is g e n e r a l l y a d e c r e a s e in v e r b a l i z a t i o n c o n c o m i t a n t with p s y c h o m o t o r r e t a r d a t i o n . F u r t h e r evidence in f a v o r o f this i n t e r p r e t a t i o n was found by O s d a n s k y and Chapman,~S who f o u n d t h a t n o r m a l subjects m a d e similar e r r o r s to S c h i z o p h r e n i c s on a s o r t i n g t e s t when forced t o r e s p o n d rapidly. H a w k s and P a y n e 19 c o n c l u d e t h a t "'the view t h a t overinclusive t h i n k i n g as c o n v e n t i o n a l l y m e a s u r e d is significantly affected by a p a t i e n t ' s r e s p o n s i v e n e s s is l a r g e d l y c o n f i r m e d . ' " T h e y suggest t h a t m a n i c p a t i e n t s w o u l d s c o r e high on conventional measures of overinclusion. T h e similarity of the Manic-DepressiveManics" scores and t h e S c h i z o p h r e n i c s " scores in this s t u d y is c o n s i s t e n t with this interpretation. SUMMARY

T h e G o l d s t e i n - S c h e e r e r o b j e c t - s o r t i n g t e s t was a d m i n i s t e r e d to 125 subjects over a period o f 14 m o n t h s , T h e subjects included s c h i z o p h r e n i c patients, m a n i c d e p r e s s i v e p a t i e n t s , o t h e r p s y c h i a t r i c p a t i e n t s ( p a r a n o i d s and n o n p a r a n o i d s ) can-

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not be differentiated from manic-depressive patients in the manic phase of their illness, although they are easily differentiated from manic-depressives in interphase and normal controls. It seems thatthis test is not a useful measure as a differential diagnostic tool, but may have some value as an indicator of a general impairment in psychologic functioning. REFER ENCES

1. Mayer-Gross W, Slater E, Roth M: Clinical Psychiatry. Baltimore, Williams & Wilkills, 1969 2. Bleuler E: Dementia Praecox or the Group of Schizophrenias. New Y o r k , International Universities Press, 1950 3. Fish F: An 'Outline of Psychiatry. Brr~tol, John Wright & Sons, 1968 4. Feigner JP, Robins E, Guze SB, et al: Diagnostic criteria for use in psychiatric research. Arch Gen Psychiatry 26:57-63, 1972 5. Breakey WR, Goodell H: Thought disorder in mania and schizophrenia evaluated by Bannister's grid test .for schizophrenic thought disorde_r. Br J Psychiatry 120:39, 395, 1972 6. lanzito BM, .Cadoret R J, Pugh DD: Thought disorder in depression. Am J Psychiatry 131:6, 703-707, 1974 7. Cameron N: Reasoning, regression and communication in schizophrenics. Psychological Monographs 50 (I, Whole No. 221), 1938 8. Goldstein K: Methodological approach to the study of schizophrenic thought disorder, in Kasanin JS (Ed): Language and Thought in Schizophrenia. New York, Norton, 1944 9. Payne RW, Matussek P, George El: An experimental Study of schizophrenic thought disorder. J Ment Sci 105:627-652, 1959 10. Payne RW, Hawks DV, Friedlander D, Hart DS: The diagnostic significance of overin-

elusive thinking in an unselected psychiatric population. Br J Psychiatry 120:173-182, 1972 I i. Harrow M, Himmelhoch J, Tucker G, et al: Overinclusive thinking in acute schizophrenic patients. J Abnorm Psych01 79:2, 16 !- 168, 1972 12. Harrow M, Harkavy K, Bromet E, T uciler G J: A longitudinal study of schizophrenic thinking.Arch Gen Psychiatry 28:179-182, 1973 13. Lovibond SH: The object sorting test and conceptual thinking in schizophrenia. Aust J Psychol 5:52-70, .1954 14. Hays WL: Statistics for Psychologists. New York, Holt, Rinehart, and Winston, 1963 15. Lidz T, Wild C, Schafer S, et al: Thought disorders in the parents of schizophrenic patients: a study utilizing the object sorting test. Psychiatr Res 1:193-200, 1962 16. Schneider K: Clinical Psychopathology. New York, Grune & Stratton, 1959 17. Payne RW, Hewlett JHG: Thought disorder in psychotic patients, in Eysenck HJ (ed): Experiments in Personality, vol 1I: Psychodiagnostics and Psychodynamics. London, Routledge and'Kegan Paul, 1960, pp 3-104 18. Usdansky F , Chapman T J: Schizophrenic-like responses in subjects under .time pressure. J Abnorm Soc Psychol 60:143-146, 1960 19. Hawks DV, Payne RW: Overinclusive thought disorder and symptomatology. Br J Psychiatry ! 18:663-670, 1971

The object-sorting test as a differential diagnostic tool.

The Object-Sorting Test asa Differential Diagnostic Tool Patrick J. Collins. Cathy Clark, Baron Shopsin, George Sakalis, and Gregory Sathananthan p...
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