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LILIENFELD, D. M. Lunar effect on mental illness. Amrican Journal of Psychiatry, 1969, 186, 1454.

OSBORN, R. D. The moon and the mental hospital: An investigation of one area of folklore. Journal of Psychiatric Nursing, 1968, 8, 88-93.

POKORNY, A. D. Moon phases, suicide, and homicide. American Journal of Psychiaty, 1964, 181, 6667.

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752-754.

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RELATIONSHIP OF MILD DEPRESSION TO PSYCHOLOGICAL DEFICIT IN COLLEGE STUDENTS

DAVID J. BERNDT~ SHEILA M. BERNDT

Loyola University of cllimgo

Illinois Masonic Hoepita1 mioago, Illinoak

Twenty- five mildly depressed and 25 nondepressed college studenta, identified on the basis of their scores on two self-report depression measures, were dis- tinguished by a discriminant analysis of their scores on six measures of sycho- logical deficit. The significant function correctly identified.88% of tge non- depressed group and 92% of. the mddly depressed group mth four variables: Paired easy associates, a &git symbol test, a wnting spec task, and Neckar Cube reversals. A measure of short term memory and pwed hard associates did not load on the discriminant function. Results were inte reted as sug- estive evidence that mild depression. is associated with a dzc i t in energy

swing both initial perceptual processing, and organization and execution of psychomotor tasks.

Most studies of cognitive , perceptual, and psychomotor deficits in depression have employed clinical populations and often have compared depressives with schizophrenics or normals on a few similar tasks, (e.g., Korboot & Yates, 1973; Payne, 1973). The most thorough and systematic investigation of psychological deficit in depression is probably a study by Friedman (1964), which compared a severely depressed sample with a matched group of normals on 33 tasks. Of the 82 scores derived from these measures, only nine significant differences were re- ported.

Miller’s (1975) review of psychological deficit in depression, however, noted several converging studies that demonstrated differences that held up across sub- types of depression. Particularly relevant to the present study is Miller’s observation

‘Requests for co ies of the article should be sent to the senior author a t the Department of Psychology, Loyola eniversity, Chicago, Illinois 60626.

PsychoEogical Deficit in Depression 869

of the general similarity between results found in studies that used depressive college students and those that investigated more severely depressed samples. Although this evidence might be taken as support for a single dimension of de- pression such as the severity dimension advocated by Kendell (1968), the present authors believe that such a conclusion would be premature. Nevertheless, Miller’s review indicates that psychological deficits exist in college students who are ex- periencing mild depression, and this is an area worthy of study in and of itself.

Berndt, Petzel, and Berndt (in press) noted that nearly two-thirds of the articles on depression published in two APA journals recently used college students rather than clinically depressed samples. In the same study, the authors present a depression inventory developed expressly for use with normal populations and suggest that their Multiscore Depression Inventory (MDI) might be a more use- ful tool for studies that investigated less severe forms of depression than the self- report measures developed on clinically depressed samples (e.g., Beck, Ward, Mendelson, Mock, & Erbaugh, 1961; Zung, 1965). The primary purpose of the present study, then, is to investigate the nature of psychological deficits associated with mild depression as identified by students’ scores on the MDI.

Miller (1975) criticizes most of the studies he reviews for lacking a theoretical orientation. Since Miller’s review, however, a great deal of research has accumu- lated that investigates psychological deficit in mildly depressed college students, and much of this research is better grounded in theory. For example, several studies (e.g., Hiroto & Seligman, 1975; Klein & Seligman, 1976) have investigated deficits from the perspective of Seligman’s (Abramson, Seligman, & Teasdale, 1978; Selig- man, 1975) learned helplessness theory. Another set of studies (e.g., Hale & Strick- land, 1976; Strickland, Hale, & Anderson, 1975) have provided evidence that Beck’s (1967) cognitive theory can account for some of the psychological deficits associated with depressive affect in college students. Although there is a definite need to evaluate these and other theories, theoretically bound research may have a limiting effect on the scope of investigation into the nature of these psychological deficits. For example, much of the research (but not all) generated by the learned helplessness model follows variations of the same paradigms and focuses on de- pendent measures that assess parameters of learning, while they rarely directly examine questions such as perception or psychomotor retardation. The authors of the present study believe that, for the moment, there is a need for more basic research at the descriptive level, and the present study is designed as a step toward more systematic investigation of the kinds of deficits associated with depressive affect.

The present study was not, however, conceived in a theoretical vacuum. Selection of variables for investigation was in keeping with a view of man as a processor of information. Measures were selected, then, on the basis of two criteria. First, a range of variables were chosen so that some initial evidence might be gathered about the relative importance of stages postulated by current theories of information processing, particularly the one described by Shiff rin and Geisler (1973). Second, an effort was made to select measures of psychological deficit that had been shown in previous studies to be related to depression.

Because our intent was to use a multivariate approach, our small sample of Ss limited the number of permissible variables because it was desirable to avoid an overdetermined correlation matrix. Six measures were selected for the study. As a measure of speed and flexibility of visual-spatial perception, the Cube Test (Meldman, 1965) was employed. The number of reversals on the Neckar Cube consistently has been found to be an important variable in severe depression (Cam- eron, 1936; Friedman, 1964; Hunt & Guilford, 1933), although Velton (1968) did not find more reversals for an ambiguous figure using his mood induction technique. Short term memory, or temporary working memory, is an important construct in many contemporary models of information processing (e.g., Shiff rin & Geisler, 1973), particularly because it is considered the stage at which decision

870 Journal of Clinical Psychology, October, 1980, VoZ. 36, No. 4.

making and other executive functions are effected. Henry, Weingartner, and Murphy (1973) provided the most careful study to date of both short term memory and long term memory in depression and concluded that depression does not di- rectly affect short term memory, but interferes with the transfer of information between short term and long term memory. For the present study, the Peterson and Peterson (1959) paradigm was chosen as the best available index of short term memory. In an effort t o measure what Shiffrin and Geisler (1973) refer to as long term working memory, Paired Easy and Paired Hard Associates from the Wechsler (1945) Memory Scale also were included. Both of these scores were among the nine significant differences reported in the study by Friedman (1964). A writing speed task demonstrated by several authors (e.g., Hale & Strickland, 1976; Velton, 1968) to be related to depressive affect in college students was in- cluded because it appears to be a good measure of response output deficit, which is relatively uncontaminated by memory effects. Finally, the sixth measure em- ployed was a digit symbol task similar to the digit symbol subtest of Wechsler’s (1955) Adult Intelligence Scale. Performance on the digit symbol test was regarded by Rappaport, Gill, and Schafer (1968) as an index of psychomotor speed; however, it is a complex task that includes active coordination of visual-motor activity along with a memory component. Besides Friedman (1964), several other investi- gators have found digit symbol impairment t o be related to depression (e.g., Hale & Strickland, 1976; Velton, 1968).

METHOD Subjects

Students from the S pool of introductory psychology classes a t Loyola Uni- versity of Chicago participated voluntarily in the study. Altogether 263 students completed the MDI and the Beck et al. (1961) Depression Inventory (BDI) at the beginning of the semester, as part of a study reported elsewhere (Berndt et al., in press). From this initial sample, extreme scores on the MDI were identified and contacted by telephone, a t which time their ‘voluntary participation was solicited. Seven students (4 nondepressed, 3 depressed) declined to participate or did not show up for the experiment, which left a final sample of 25 depressed (10 male, 15 female), and 25 nondepressed (10 male, 15 female) students. Scores above 50 on the MDI were considered depressed, while the criteria for the non- depressed group was an MDI score below 10. These cut-off points were based on local norms. The depressed group scored x = 14.61 on the Beck et al. (1961) Depression Inventory, which was significantly greater than the scores of the non- depressed group, x = 4.12, t (48) = 6.62, ( p <.001).

Procedure Students participated in individual sessions with an E blind to experimental

groups and completed the tasks in the following order. The digit symbol test was similar to the digit symbol test of the Wechsler

(1955) Adult Intelligence Scale. Ss were given standard instructions and 90 seconds to copy the symbol. The computed score was the number of correctly copied sym- bols.

For the next task, students were shown the Neckar Cube, which is an ambiguous cube in which the directions are reversible. Students were given the following instructions: “This is an ambiguous cube. It is ambiguous because, as you look at it, you will eventually see it change perspective, so the cube will appear t o be facing a different direction. Look a t it and let me know when you see the cube change.” When a student indicated that he had seen a reversal, the E covered the cube and said “What I want you to do is say ‘now’ every time you see the cube shift until I tell you to stop.” The E timed the student for 20 seconds and recorded the number of reversals reported by the student.

Psychoiogical Dejcit in Depression 87 1

The third task was the paired associates task from the Wechsler (1945) Memory Scale. This consists of 10 pairs of words, of which 7 are “easy” or common associates and 3 are “hard” associates, in which there is no apparent connection between the paired words. Standard administration procedure was followed, except that there was a IO-second delay between each termination of the list and commence- ment of the recall probes. This delay was designed to decrease the influence of short term memory, while it allowed additional time for encoding. Separate scores were computed for correctly recalled easy and hard associates.

Writing speed was assessed by giving the student a blank sheet of paper and instructing the student to write numbers from 100 in descending order from top of the paper, working as rapidly as possible, and starting a new column if necessary. The score was the total number completed after 1 minute.

Finally, each student participated in a Peterson and Peterson (1959) type paradigm, in which the student was asked to recall a random three-consonant string after a 10-second interval. During the interval the student performed a distraction task by counting backward by three’s from large numbers. The dis- traction task was designed to prevent rehearsal. The score was the number of correct,ly recalled three-consonant strings out of a list of 20.

RESULTS In order to determine the best linear combination of the six measures that

would optimally distinguish the depressed and nondepressed groups, a discriminant analysis was applied to the data. Table 1 shows the standardized discriminant function coefficients for the four variables that formed the discriminant function that maximized discrimination between depressed and nondepressed groups (Wilks

TABLE I

STANDARDIZED DINRIMINANT FUNCTION COEFFICIENTS FOR VARIABLES

NONDEPRESSED STUDENTS DI~TINGUXSHING DEPRESSED AND

Variable Coefficient

Paired Easy Associates - .624 Writing Speed .520 Neckar Cube Reversals .509 Digit Symbol Teat .423

Note.-Positive value is in direction of nondepreased group.

7 = .655, x2 (4) = 19.50, p <.001). A moderately good canonical correlation of .59 related the discriminant function to the depressed/nondepressed dichotomy. On the basis of the four variable discriminant function, 88% of the nondepressed and 92y0 of the depressed group could be classified correctly. This, however, over- estimates the function’s utility because it was used to classify the same cases from which the functions were derived.

DISCUSSION The discriminant analysis provides some interesting results which, if inter-

preted cautiously, may suggest something about psychological deficits that may accompany mild depression.

First, if the MDI and BDI are effectively identifying mildly depressed col- lege students, then i t appears that a set of psychological deficits may be associated with depression in this kind of population. Miller (1975) concludes that depressed

872 Journal of Clinical Psychology, October, 1980, Vol . 36, No. 4.

normals appear to have psychological deficits similar to those of clinical groups. However, the present sample of “depressed” college students, and samples in other studies using normal groups, simply may be demonstrating a performance decrement associated with anxiety. While the present study is an improvement over most similar studies, in that the sample is characterized as depressed by two inventories, nevertheless research that compared anxious students with depressed and normal samples would be more informative. As an additional check, a retro- spective look at the configuration of the subscales of the MDI indicated that the scales on which the depressed sample tended to score highest were not the ones that typically correlate highest with anxiety. The use of a configural approach, however, can be suspect due to the lower reliability of configural scores.

If, then, one accepts that mild depression characterized the depressed sample in the present study, the discriminant analysis may provide some interesting clues to the nature of psychological deficit in mild depression. The discriminant function provides a parsimonious description of the most useful way of combining the variables in order to distinguish the depressed from the nondepressed groups. As such, it capitalizes on sample specific error, and cross validation would be neces- sary before the stability of the function could be assumed. One particularly dif- ficult problem that arises in any discriminant analysis is that different reliabilities for a measure can affect its prominence in the discriminant function, and the results in Table 1 therefore may be somewhat misleading. In addition, discriminant analy- sis takes into account each variable as a member of a set of variables that operate together to separate the groups, and does not focus only on each item in isolation. Consequently, the use of the less stringent but more familiar univariate procedure would produce a different picture. Paired easy associates, for example, contributes the most to the function when the variables are viewed as a set, but with the uni- variate analysis it would not be significant. Comparison of the standardized dis- criminant function coefficients in Table 1, despite the above mentioned limitations, suggests some tentative conclusions.

Perhaps most noteworthy is the absence of the short term memory variable and the measure of paired hard associates from the function. Their absence indi- cates that the other four variables were able to account for any significant ability to discriminate that these measures may have been able to contribute. The findings contrast with Friedman’s (1964) suggestion of possible short term memory deficit in severe depression. However, Friedman based his conclusion primarily on sig- nificant findings on paired easy and paired hard associates, and he found no sig- nificant differences on a digit span test. The Peterson and Peterson (1959) paradigm appear to be a more careful measure of short term memory, due t o control for rehearsal. The present study, meanwhile, conceptualized paired easy and paired hard associates as more relevant to long term working memory (Shiffrin & Geisler, 1973), and an effort was made to strengthen such an inference by the insertion of a 10-second pause after each list presentation. The lack of significant findings for our short term memory measure, or for hard associates, indicates that the present sample of mildly depressed college students apparently had little difficulty with either short term memory, or the early levels of encoding and retrieval of difficult learned material. In addition, the largest coefficient for the discriminant function was for paired easy associates, and the negative sign indicates, if any- thing, that the mildly depressed sample was better able to remember recently proces- sed material, so long as it had easy semantic associations. While the easy associates results are interesting, they should be replicated before much is made of them.

In other respects, our findings are very similar to those of Friedman (1964) with his severely depressed sample. Friedman attributed Significant differences on both the digit symbol test and reaction time to psychomotor retardation, and the results of the present study for writing speed and the digit symbol test indicate a parallel deficit in the mildly depressed sample. Similar results with college students also were obtained, on both measures, by Hale and Strickland (1976), and by

Psychological Deficit in Depres,yion 873

Velton (1968). While the writing speed test appears to be a relatively pure measure of the organization and rapid execution of a simple motor task, the digit symbol appears more complex and includes both memory and executive functions. The finding of relatively high loadings on both measures may indicate that other com- ponents tapped by the digit symbol test, besides simple slow writing movements, are characteristic of the depressed sample.

The results with the Neckar Cube are also in agreement with those of Fried- man (1964), who speculated that it may be associated with flexibility, or the ability to shift mental set. Miller (1975) included the Neckar Cube in his review under the discussion of visual-perceptual phenomena and suggested that the differences may be an artifact of different criteria for reporting reversals. Others, (Meldman, 1965; Weinstein, DeWolfe, & Sittig, 1968) have used it to measure energy available for adaptive use. In our own research (Berndt & Milord, Note l), cube reversals have been found to relate to extremely fine perceptual discrimination performance, as well as to a self-report measure of energy level. Consequently, we prefer to tentatively view the results as indicating that a depressed mood may be associated with slower perceptual processing. Such a conclusion would be supported by some research with other paradigms on clinically depressed samples (e.g., Byrne, 1976; Payne & Hewlett, 1960).

The results of the present study, then, provide some interesting clues to the possible nature of psychological deficit associated with mild depression. No evidence was found for a deficit in short term memory, or in long term working memory. However, the present study did produce results that suggest a possible deficit in energy used for both initial perceptual processing, and for the organization and execution of simple and complex psychomotor tasks. Although several alternative explanations could account for these data, particularly lower motivation, or inter- ference from anxiety, we prefer to use the more descriptively neutral term “energy” until these and other alternative hypotheses can be ruled out effectively. By “ener- gy,” we do not mean to either imply or exclude hydraulic explanations, not. do we mean to emphasize information processes to the neglect of stages of processing. Nevertheless, the results help to bring a focus to the research on psychologml deficit in mild depression and demonstrate the utility of a more descriptive methodo- logy conceptualized within the information processing perspective.

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