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60 •• 50 -- æ 30 - 20 - - 10 - - 10 20 30 70 80 score 90 100

cut off scores 47 63 71

controls % 5 25 50

left lesions % 30 68 85

right lesions% 15 55 78

B Effect of laterality o f lesion on new test

The next task was to compare the frequencies within each cut offhand across experimental series. Again the chi square test for linear trend was selected, for the reasons discussed in the preceeding section. The tables of the observed and expected frequencies used to calculate the chi squares are given in Appendix XIII. The chi square values and their probability values are given in Table 27.

Inspection o f Table 27 reveals that whilst the left hemisphere lesion group were

significantly impaired on all six sections of the new test, the right hemisphere lesion group were not impaired on verbal odd one or verbal analogy. Following from these statistics, comparisons o f the left and right lesion series only demonstrated significant differences on verbal odd one and analogy. The significantly impaired performance of both lesion series on the non verbal and total composite reasoning scores is predictable from the two lesion series scores on the individual sections of the test. The impairment of both lesion series on

test left hemisphere lesions compared with controls right hemisphere lesions compared with controls

right and left hemisphere lesions a comparison

1. Verbal odd one 15.68*** 2.74 6.61*

2. Verbal analogy 19.04*** 3.61 4.94*

3. Verbal series 14.74*** 12.68*** 0.20

4. Non-verbal odd one 10.53** 5.40* 0.84

5. Non-verbal analogy 12.69*** 16.82*** 0.71

6. Non-verbal series 9.71** 11.77*** 0.10

7. Composite verbal score 16.41*** 7.01** 3.20

8. Composite non-verbal score 11.14*** 8.42** 0.04

9. Total composite score 17.08*** 8.62** 2.30

Table 27. Chi squares for linear trend comparing the lesion and control groups on the six sections of the new test and the three composite scores. * p<0.05 ** p<0.01. ♦♦♦p<0.001.

the composite verbal reasoning score is less congruent with their performance on the individual verbal odd one and verbal analogy sections, where there was no demonstrated impairment of the right hemisphere lesion group. The apparent discrepancy was probably due to the control group achieving a better average over more items, whilst the lesion patients in general were more likely to experience difficulty over a range of problems, which exposed the patchiness and inconsistency of their cognitive function.

In addition to the chi square analyses of fi’equencies of lesion and control subjects’ scores falling below the specified cut offs, traditional analyses of variance were used to compare the score distributions on the new test, with age as covariate. The results are given in Table 28.

left hemisphere lesions compared with controls right hemisphere lesions compared with controls r i ^ t and left hemisphere lesions a comparison

ANOVAF ANOVAF ANOVAF

1. Verbal odd one 28.60*** 3.62 6.83*

age t~value -3.56*** -3.87*** -2..63*

2. Veibal analogy 48.08*** 9.03** 10.53**

age t-value -4.32*** -4.37*** -3.54***

3. Verbal series 28.95*** 19.93*** 1.02

age t-value -2.32* -2.69** -2.53*

4. Non-verbal odd one 16.58*** 7.59** 1.27

age t-value -3.66*** -3.81*** -3.57***

5. Non-verbal analogy 21.43*** 31.11*** 0.07

age t-value -4.33*** -5.11*** -3.82***

6. Non-verbal series 19.66*** 32.37*** 0.05

age t-value -6.00*** -6.20*** -5.32***

7. Composite verbal score 48.34*** 7.63** 10.04**

age t-value -4.42*** -4.59*** -3.34***

8. Composite non-verbal score 27.61*** 26.51*** 0.09

age t-value -4.49*** -5.23*** -4.23***

9. Composite total score 46.11*** 18.86*** 3.95*

age t-value -4.91*** -5.22*** -4.10***

Table 28. Comparison of the two lesion series with control series, and o f the two lesion series, on new tests by analysis of variance with age as covariate. * p<0.05 ** p<0.01. ***p<0.001.

The ANOVA results describe a similar pattern of significant differences to the chi-square analyses, with three additions. The first is that the ANOVA produces a significant

difference for the right lesion series on the verbal analogy section. The remaining two additional significant differences are between the right and left hemisphere lesion patients

on the verbal composite score and the total composite score. The weakness of the right hemisphere group on verbal analogy was exposed by giving equal weight to all parts of the score distribution. However, when the more impaired sections of the distribution are emphasised, by the chi square method, then the right lesion patients are not significantly different fi"om control subjects. The significant differences between the two lesion series on the composite scores led to an exploration of the pattern of these scores obtained by lesion patients.

Next the diflferential effect of unilateral cerebral lesions on each type of reasoning was considered. Sternberg and Gardner’s 1983 findings with normal subjects were discussed in section 1.4B. Briefly, the investigators interpreted the differing response times of their subjects to three types of reasoning problems as evidence that classification tasks require less cognitive processes than series completion tasks, which require less processes than analogy tasks. If the lesion patients in this study could be shown to be most impaired on the analogy section, less impaired on the series section and least or not impaired on the odd one section, then the results could be taken to support Sternberg and Gardner's work.

The pattern of varying impairment could be explained in terms of brain damage being more likely to affect at least one of the seven cognitive processes Sternberg suggests are

required for analogy problems, slightly less likely to disrupt one or more of the six

processes required for series completion, and least likely to disrupt one or more of the five processes required for classification tasks. Taking this as a prediction from the Sternberg and Gardner theory, the following hypotheses were generated:

HI For left hemisphere lesion patients.

Verbal odd one > Verbal series > Verbal analogy

H2 For left hemisphere lesion patients.

Non-verbal odd one > Non-verbal series > Non-verbal analogy

and therefore Non-verbal odd one > Non-verbal analogy

H3 For right hemisphere lesion patients.

Verbal odd one > Verbal series > Verbal analogy

and therefore Verbal odd one > Verbal analogy

H4 For right hemisphere lesion patients.

Non-verbal odd one > Non-verbal series > Non-verbal analogy

and therefore Non-verbal odd one > Non-verbal analogy

Using the frequencies detailed in Appendix XU, of lesion patients scoring at or below the 5th percentile, at or below the 25th percentile, at or below the 50th percentile and above the 50th percentile on each section of the new test, according to the control subjects in their age group, chi squares for linear trend were performed to see if the hypotheses were supported by this study.

Left lesion group Right lesion group

verbal odd one cf. series p=0.06 p=0.05*

verbal series cf. analogy p=0.02* p=0.05*

verbal odd one cf. analogy p=0.75 p=1.00

non-verbal odd one cf. series p=0.91 p=0.20

non-verbal series cf. analogy p=0.67 p=0.35

non-verbal odd one cf. analogy p=0.06 p=0.03*

The chi square for linear trend test was thought to be the most sensitive for detecting different “hit rates” among the sections of the new test of reasoning. The results are

summarised in Table 29. Using the analyses summarised in Table 29, we can reconsider the hypotheses.

HI For left hemisphere lesion patients,

Verbal odd one (NS) Verbal series > Verbal analogy

and therefore Verbal odd one (NS) Verbal analogy

H2 For left hemisphere lesion patients.

Non-verbal odd one (NS) Non-verbal series (NS) Non-verbal analogy

and therefore Non-verbal odd one (NS) Non-verbal analogy

H3 For right hemisphere lesion patients.

Verbal odd one > Verbal series < Verbal analogy

and therefore Verbal odd one (NS) Verbal analogy

H4 For right hemisphere lesion patients.

No- verbal odd one (NS) Non-verbal series (NS) Non-verbal analogy

and therefore Non-verbal odd one (NS) Non-verbal analogy

Of the 12 predicted relations, 2 were confirmed, 9 did not differ significantly and 1 differed significantly in the opposite direction. These results will be discussed in the lesion study discussion.

Because the composite scores failed to differentiate between the left and right hemisphere groups, the discrepancy between the composite verbal and composite non-verbal scores was examined. It seemed likely that the increased variability of lesion patients’ performance was influencing the summation of scores within groups. The discrepancy between the total

score on verbal odd one and verbal analogy, and the total score on nonverbal odd one and non-verbal analogy for each case was calculated. Thus subjects whose scores were the same for both composite totals achieved a discrepancy score of 0. Subjects whose verbal composite score was greater than their non-verbal composite score, achieved a positive discrepancy score. Conversely, subjects whose verbal composite score was less than their non-verbal composite score, achieved a negative discrepancy score. The individual discrepancy scores were considered in three groups: the control sample, the left

hemisphere lesion group and the right hemisphere lesion group. The distributions of the discrepancy scores for each group are given in the following Figure 8.

Inspection of the graphs reveals that, whereas the control group were evenly distributed around 0, the lesion groups’ discrepancy distributions were apparently skewed. The left hemisphere group had rather more negative discrepancies, that is their verbal composite scores were more often less than their non-verbal composite score. In contrast, the right hemisphere lesion group had more positive discrepancies, that is their verbal composite scores were more often greater than their non-verbal composite scores. Table 30 summarises these differences.

Discrepancy<0 Discrepancy>0 or =0

Control group 75 78

n=155

Left lesion group 30 10

n=40

Right lesion group 13 26

n=40

Table 30. Numbers o f control, left lesion and right lesion groups with positive or negative discrepancies. Two control subjects and one right hemisphere subject had not attempted all four of the component tests

Figure 8. The distributions o f the discrepancies between verbal and non-verbal composite scores. The control group data is at the top, the left hemisphere lesion group data is in the middle and the right hemisphere lesion group data is given in the third graph.

1. Control group. Range -15 to 16.

y !o 16 IS 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 00 Of Uf G lO 00 to discrepancy score

2. Left lesion group. Range -1 4 to 6.

8

ti

eo lo o i o> T- T- V ' <9 discrepancy score O (D 0 » CM W>

3. Right lesion group. Range -9 to 13.

8

il

1 0

nnnll. n

M 0 ^ <9 <9 O (O (O discrepancy score 144

To determine the statistical significance of these trends, two chi squares were performed using the fi^equencies fi’om the two lesion groups with expected fi'equencies of 20 for the other two cells. The left hemisphere group’s fi'equencies were significantly different fi*om the expected fi’equencies (p=O,021), but the right hemisphere group’s fi'equencies were not significantly different fi'om the expected scores (p=0.133). A chi square comparison of the left and right lesion series’ frequencies produced a highly significant result (p=0.0002).

c Effect of lesion quadrant on new test

(Control Left Left Right Right

group anterior posterior anterior posterior

1. verbal odd one 16.7 13.7 13.1 16.8 14.7

(maximum score 25) (3.3) (3.6) (5.6) (2.3) (4.1)

2, verbal analogy 17.5 14.1 12.2 16.8 14.5

(maximum score 25) (3.8) (3.3) (5.6) (3.6) (4.1)

3. verbal series 17.4 14.3 13.3 15.2 13.5

(maximum score 25) (3.8) (5.1) (4.6) (3.6) (4.3)

4. non-verbal odd one 16.6 15.6 14.3 16.3 14.6

(maximum score 25) (2.3) (2.4) (3.3) (2.3) (3.5)

5. non-verbal analogy 18.4 16.2 14.5 15.6 13.5

(maximum score 25) (3.9) (4.3) (5.9) (3.7) (5.5)

6. non-verbal series 20.8 19.8 17.5 18.2 16.9

(maximum score 25) (2.9) (3.2) (5.4) (3.9) (4.8)

7. composite verbal score 34.2 27.9 25.3 33.7 29.2

(maximum score 50) (6.4) (6.0) (10.7) (5.1) (7.5)

8. composite non-verbal score 35.0 31.9 28.8 31.8 28.2

(maximum score 50) (5.5) (6.1) (8.3) (5.2) (8.0)

9. total composite score 69.3 59.7 54.1 65.5 57.4

(maximum score 100) (10.9) (11.5) (17.7) (8.7) (14.4)

Table 31. The means and standard deviations of the four quadrant groups on each section of the new test.

The data of the two lesion series were examined. Patients were grouped according to the quadrant in which their lesion ocurred. As in the analysis of the effects of lesion location on

142 scores on established tests, patients with frontal, fronto-temporal and fronto-parietal lesions on CT scan were designated “anteriori’. All other patients were designated “posterior”, with the exception of two patients from each series who had lesions involving three lobes. The extensive nature of their disease meant that they were unsuitable for inclusion in a detailed localisation study. The means and the standard deviations of the four groups are given above in Table 31.

In general, the right posterior group means appear to be less than the right anterior group means. The trend for the posterior group to be weaker seems to be less pronounced in the left lesion groups. The left hemisphere lesion groups perhaps have marginally greater standard deviations on average. A set of analyses of variance was performed to compare the scores of patients with lesions in different quadrants. Age was covaried as part of the analysis. A summary of the findings is given in Table 32.

An examination of Table 32 reveals very few significant differences between the comparisons of the four lesion quadrant groups on the new reasoning test. Among the single test

comparisons, only verbal odd one and verbal analogy were significantly different and only in the comparison of the left and right anterior lesion groups. The left anterior group performs most poorly in both cases. Interestingly, these were the only two single sections of the new test to discriminate between the two unilateral lesion series (see Table 25). The results from the quadrant ANOVA's summarised above suggests that most of the difference between the two unilateral series resulted from the scores of the anterior cases, because when analysing individual sections of the new test, neither the comparison of the two posterior groups nor the two within hemisphere comparisons showed any significant differences.

LA vsL P RA vsR P LA vs RA LP vsR P

ANOVAF ANOVAF ANOVAF ANOVAF

Verbal odd one 0.01 3.82 7.63* 1.30

age t-value -1.55 -2.65* -1.06 -2.72**

Verbal analogy 0.11 3.44 9.32** 3.09

age t-value -3.50*** -2.22* -2.98** -3.20**

Verbal series 0.00 1.64 0.66 <0.00

age t-value -1.86 -2.12* -1.08 -2.75**

Non-verbal odd one 0.37 2.84 1.63 0.06

age t-value ** -2.40* -2.12* -3.10**

Non-verbal analogy 0.04 2.27 <0.00 0.88

age t-value -2.67* -3.49*** -1.20 -4.72***

Non-verbal series 0.26 1.19 0.07 0.37

age t-value -4.16*** -3.70*** -4.23*** -4.35***

Composite verbal score 0.02 4.58* 11.55** 2.38

age t-value -2.59* -2.72 -2.34* -3.16**

Composite non-verbal score 0.16 3.34 0.23 0.29

age t-value -3.05** -3.53*** -1.72 -4.71***

Composite total score 0.07 4.96* 4.53* 0.46

age t-value -3.04** -3.51*** -2.27* -4.24***

Table 32. Summary of analyses of variance comparing new test scores o f patients with right and left, anterior and posterior cortiœl lesions, with age as covariate. The significant différences between groups are printed in

bold.

LA = Left Anterior, LP = Left Posterior, RA = Right Anterior and RP = Right Posterior.

In addition, there were significant differences demonstrated between the composite verbal and total composite scores. These differences ocurred both when left and right anterior lesion groups were compared, as in the two verbal sections when considered singly, and also in the comparison between anterior and posterior right lesion cases. The left anterior lesion group was more impaired than the right anterior lesion group. Intriguingly, it is the right posterior group who are weakest on both the verbal composite score and on the total composite score, in comparison with the right anterior group.

(v) EFFECT OF FOCAL DEFICITS ON NEW TEST

Having established that the three focal tests distinguished between the left and right hemisphere lesion groups (see Table 19), the effect of verbal and perceptual focal skills on performance on the new test could be considered. In order to evaluate the effects of focal brain damage on the new test, it was necessary to examine systematically how such acquired deficits as aphasia and perceptual disorders affected patients’ performance.

Multiple regression was chosen as a method of assessing how much of the variance of the new test scores was attributable to functional compromise of either hemisphere. The Graded Naming Test and the Unusual Views test were selected from the battery as indicators of the integrity of dominant and non dominant hemisphere function. Age was also included as a variable because of its importance in determining the scores of the control subjects, which was discussed in section 2.3B(i). In addition the sex of the patients was included in the analysis for the reasons outlined in section 2.4B(i). In summary, twelve multiple regressions were performed, one on each of the six sections of the new test for both left and right hemisphere lesion groups separately. The variables examined were age, sex and the scores on Unusual Views and the ONT.

The variables found to contribute to the variance of the new test scores with a probability level of less than 0.05 are given below;

1. Left hemisphere lesions 2. Right hemisphere

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