Money Road

Pergamon Archives of Clmicd Neuropsychology. Vol. 11, No. 1, pp. l-9, 1996

Copyright Q 1995 National Academy of Neuropsychology Printed in the USA. All rights reserved

0887-6177/% $15.00 + .OO

Analysis of the Money Road-Map Test Performance in Normal and

Brain-Damaged Subjects

Guy Vingerhoets, Engelien Lannoo, and Sabien Bauwens

Department of Psychiatry and Neuropsychology, University of Gent

The Money Road-Map Test (MRMT) is a paper and pencil assessment of lef-right discrimination. Some of the answers require an egocentric mental rotation in space. In a first experiment with 63 normal adults. we found that the accuracy and speed of the left-right decision process significantly decreased with an increasing degree of mental rotation required. A division of the MRMT turns in three categories with increasing mental rotation was proposed. In a second study (n = 50), patrents with predominantly parietal brain lesions performed significantly worse than patients with predominantly frontal lesions. The si,@ficant group difference in total error score was especially due to the error scores of turns requrring mental rotation. The turn type analysis did not contribute to the lateralization of the lesionr

The Standardized Road-Map Test of Direction Sense (Money, Alexander & Walker, 1965), generally referred to as the Money Road-Map Test (MRMT), measures left-right orientation with and without egocentric mental rotation in space. The MRMT is a paper and pencil test of left-right discrimination in which the subject traces a dotted pathway through a city map, and indicates the direction taken at each turn, left or right. Some of the answers require an egocentric mental rotation, because the dotted pathway follows an erratic trace both away from and towards the subject, who is not allowed to turn the map or to make head and body movements to give the correct answer.

In analyzing the performance on the Road-Map Test we should be aware that different cognitive functions are assessed, namely the left-right discrimination per se and (if required) the ability to perform an egocentric mental rotation in space to give the correct left-right response. In examining the MRMT performances of four groups of patients with localized lesions (right parietal and temporal, left frontal and temporal), Butters, Soeldner, and Fedio (1972) suggested that the exceptionally high number of errors in the left frontal patients reflected the test’s conceptual demands for making mental spatial rotations. It was

The authors thank the reviewers of this manuscript for their helpful suggestions. Address correspondence to: Guy Vingerhoets, Department of Psychiatry and Neuropsychology,

University Hospital Gent 4K3, De Pintelaan 185, B-9000 Gent, Belgium. I

stated, however, that the absence of left parietal and right frontal groups in this study war- ranted further research to account for the left-right confusion in patients with left hemisphere damage (Lezak, 1983). In contrast to the findings of Butters et al. (1972), research on the lateralization of mental rotation skill has consistently documented a right hemispheric, and especially parietal, specialization for mental rotation (Corballis & Sergent, 1989; Deutsch, Bourbon, Papanicolaou, & Eisenberg, 1988; Ditunno & Mann, 1990; Rosier, Schumacher, & Sojka, 1990) whereas the disability of left-right discrimination is normally associated with left parietal dysfunction (Ratcliff & Newcombe, 1973; Roeltgen, Sevush, & Heilman, 1983; Strub & Geschwind, 1983).

To account for the fact that left-right discrimination and mental rotation are two different abilities, several classifications of turn types have been proposed (Flicker, Ferris, Crook, Reisberg, & Bartus, 1988; Money et al., 1965). Research evidence (Money et al., 1965) and our own clinical experience with this test, pointed to a differentiation between no rotation turns (i.e., turns in which no mental rotation is required to state a left-right decision, Figure lA), half rotation turns (Figure 1B and C), and full rotation turns (Figure 1D). It can also be argued that the left-right decision in a half rotation turn is more difficult when the half rotation decision follows a full rotation (Figure IC) than when it follows no rotation (Figure 1B).

Research on mental rotation skill repeatedly showed a significant sex difference favoring males, both under timed test conditions, and conditions in which the effects of time on performance were minimized or eliminated (Gallagher & Johnson, 1992; Kerns & Bembaum, 1991; Resnick, 1993; Thomas & Kail, 1991). It also was argued that gender differences in mental rotation skill are of limited practical value due to the large variability of the cognitive skill in both sexes (Resnick, 1993).

By assessing the response time and the accuracy score for each turn of the Road-Map Test in both male and female normal subjects, we can evaluate several hypotheses suggested by the literature. First, if the requirement of mental rotation over and above left-right discrimination makes the cognitive task more complex, we can expect lower accuracy scores

A B C D

NR HR-A HR-6

NR = no rotation

HR A : half rotation following no rotation

HR B = half rotation folIowIng full rotation

FR full rotation

FR

FIGURE I. Examples of different turn types in the Money Road-Map Test.

and longer response times in left-right decisions requiring an increasing degree of mental rotation. Second. if a left-right decision in a half rotation turn is more difficult when the half rotation decision follows a full rotation than when it follows no rotation, we can expect that a further division in four turn types (Figure 1) will show that accuracy scores and response times are worse when a right or left approach follows a full rotation movement than when a right or left approach follows a no rotation movement. Third, based on the sex differences found in the research on mental rotation skill, we can expect males to perform faster and more accurately than females in turns where a mental rotation to make a correct left-right judgement is required.

In a second study, we will compare the error scores for the different turn types of brain damaged patients with either left frontal, right frontal, left parietal or right parietal lesions. Because previous research pointed to a parietal involvement in left-right discrimination either with or without mental rotation, we would hypothesise that patients with parietal lesions show a higher error score as opposed to patients with frontal lesions. Because an intact left parietal lobe should be able to make adequate left-right discriminations when no mental rotation is required, we can also expect that patients with right parietal lesions should show a lower error score on the no-rotation turns as opposed to patients with left parietal lesions.

EXPERIMENT 1

Method

Subjects. Sixty-three healthy volunteers, consisting of young graduate and undergraduate university students agreed to take part in the study. The mean age for all subjects was 21.9 (age range 19-29). Twenty-six (41%) were males (mean age 21.3) and 37 (59%) were females (mean age 22.3).

Procedure. Each subject was tested individually. The subjects were instructed to follow the broken line, just as if they were tracing a map. and to indicate aloud whether they turned to the left or to the right. Their verbal responses were audiotaped. They were free to use their finger to trace the line, but we allowed no head and body movements. The preliminary practice route of three turns on the bottom right hand side of the test was given to assure a complete comprehension of the instructions. The subjects were then pointed to the beginning of the standard test route. The Road-Map sheet was covered and the subjects were instructed to do the test as fluently, but also as accurately as possible. The test was uncovered, and the subjects were told to start.

Design. The answer\ were recorded, and the audiotape was analyzed for accuracy and response time by use of a computerized chronometer. Response time was defined as the time lapse between two consecutive answer\

The 32 turns of the Money Road-Map standard text route were numbered and classified by each author separately in one of the three followmg categories: (a) the correct left-right indication of the turn requires no mental rotation (no rotation, NR), (b) the correct left-right indication of the turn requires a mental rotation of approximately 90” (half rotation, HR), (c) the correct left-right indication of the turn requires a mental rotation of more than 90” (but no more than 180”) (full rotation, FR).

The category of the half rotations was turther divided into half rotations following no mental rotation (HR-A), and half rotations following a full mental rotation (HR-B). A comparison of the separate classifications of e;~ch author showed a complete agreement of the division in turn types

4

We found no significant difference between both sexes on the variable of age, and on the performance of a Dutch version of the National Adult Reading Test (NART), that offers an estimate of verbal intelligence.

Response time. A three (turn type: NR/HR/FR) by two (sex) ANOVA shows a significant difference in response time for the three turn types [F(2, 114) = 99.91, p < .OOl], with gradually longer response times for an increasing degree of mental rotation required. Newman-Keuls post hoc analysis comparing means indicates significant differences between FR and both NR and HR response times. There is also a significant main effect of sex [F( 1, 57) = 5.38, p < ,051, with consistent longer response times for females. We found no significant interaction effect between sex and turn type.

A four (turn type: NRkIR-A/HR-B/FR) by two (sex) ANOVA shows similar significant main effects in response time for sex [F( I, 57) = 5.70, p < .05] and turn type [F(3, 171) = 52.54, p < .OOl] (Figure 2). Newman-Keuls post hoc analysis comparing means indicates significant differences between FR and both NR and HR-A only. Again, there is no significant interaction effect between sex and turn type.

Accuracy data. A three (turn type: NR/HR/FR) by two (sex) ANOVA shows significant differences in the percentage of correct answers for the three turn types [F(2, 118) = 30.73, p < .OOl], with a gradually decreasing accuracy score for an increasing degree of required mental rotation. Newman-Keuls post hoc analysis comparing means indicates significant differences between each turn type. There is a significant main effect of sex [F(l, 59) = 4.07, p -C .05] with a higher female error score. We found no significant interaction effect between sex and turn type.

Again, we found similar main effects for a four (turn type: NR/HR-A/HR-B/FR) by two (sex) ANOVA, indicating a significant effect of turn type [F(3, 177) = 18.70, p < .OOl] and

3 IO0 rer r, .

* A

2.5 95

I.5 .

.

. *

.

A males q females

FIGURE 2. Response times and accuracy scores for different turn types.

a significant effect of sex [F( 1, 59) = 5.63, p = .05] on the percentage of correct answers (Figure 2). Newman-Keuls post hoc analysis comparing means reveals significant differences between FR and all the other turn types, and between HR-B and NR. There is no interaction effect between sex and turn type.

Discussion

Our first hypothesis, namely an increasing response time and a decreasing accuracy score with an incremental degree of mental rotation required, was confirmed for both dependent variables in both a three and a four type division of turns. Post hoc analysis however, showed no significant differences between HR-A and HR-B results for both response time and accuracy score in the four type division of turns. The hypothesis that half rotation turns following a full rotation are more difficult than half rotation turns following no rotation was not statistically confirmed.

Marked differences between turn types were found for the three-turn scoring system. This was most notable for the accuracy scores for which significant differences between all three turn types were found. Because clinical interpretation of the Money Road-Map Test is usually based on the error score only (and not on response time), this result confirms the value of a classification in three turn types.

Based on the mental rotation research, we also hypothesized a significant sex difference in left-right discrimination requiring mental rotation favoring males. This hypothesis was confirmed for both response time and accuracy score.

EXPERIMENT 2

Method

Subjects. Fifty brain-damaged patients with localized cerebral lesions, who had been referred to our department for neuropsychological testing during the period from 1983 to 1993, were selected for the study. Only the protocols of the patients with either a left frontal, right frontal, left parietal, or a right parietal lesion were selected. A prerequisite for selection was that the reported lesions were documented by reliable neurological and neuro- radiological data (computerized tomography, CT), and that the detected lesions were restricted to the cerebral lobe involved. However, because of the inherent limits of the CT neuroimaging procedures (Damasio & Damasio, 1989), the existence of micro-structural or nonmorphological brain damage outside the specified region can not be excluded. In some of our cases, and especially in the cases with head trauma, the existence of more widespread brain damage is even likely, although no objective evidence for such damage was found. These considerations necessitate a cautious interpretation of the results.

All patients were alert and medically stable at the time of the examination. Of the 13 patients with left frontal lesions, 7 suffered contusion following head trauma, 4 suffered intracerebral hematoma, 1 suffered a posttraumatic extradural hematoma and a subdural hygroma for which neurosurgery was performed, and 1 was operated on for a brain tumor. Of the 12 right frontal lesion patients, 5 suffered contusion following head trauma, 3 suffered an intracerebral hematoma, 3 had a brain tumor (2 were operated and 1 was inoperable), and 1 patient suffered from epileptic seizures with a clear right frontal focus (as was illustrated by EEG and a right frontal hypodense spot on MRI). Of the 12 left parietal lesion patients, 5 suffered contusion following head trauma, I was operated on for a meningeal abscess, 3 suffered intracerebral hematoma, and 3 suffered from stroke. Of the 13 right parietal lesion patients, 2

suffered contusion following head trauma . 2 suffered intracerebral hematoma, 4 were operated on for removal of brain tumors, I suffered from an encephalographically localized irritative focus after an epidural hematoma, and 4 patients suffered from stroke.

Procedure. All 50 patients were individually assessed with the Money Road-Map Test as a part of a neuropsychological investigation for which they were referred by their physicians. The Money Road-Map Test was given as a paper and pencil test and they were instructed to follow the broken line, just as if they were tracing a map, and to indicate by writing down an L for left or an R for right whether they turned to the left or to the right. Turning the paper or head and body movements were not allowed. The preliminary practice route of three turns was used to assure a complete comprehension of instructions. The patients were then pointed to the beginning of the standard test route. The performance was not timed, and the patients were told to do the test as accurately as possible.

Design. The 32 turns of the Money Road-Map Test were classified in three turn types, as described earlier. The number of errors for each category of turns was used as the dependent variable.

Table 1 shows the subject variables for each group. We found no significant differences in gender distribution, age, and years of education between the four groups. This was also true when the total frontal and total parietal groups were compared.

When we compared the total frontal and total parietal groups (regardless of the side of the lesion), we found a significant difference for the total number of errors on the Road- Map Test [t(48) = -2.69, p = .Ol]. The frontal group (n = 25) averaged I.8 errors, whereas the parietal group (n = 25) averaged 5.2 errors. If we looked at the different turn types separately, we found no significant difference between both groups for the no rotation turns, but we found significant differences for the half rotation turns [t(48) = -2.39, p < ,051 and the full rotation turns [t(48) = -2.58, p = ,011.

In addition, we also evaluated if group differences in error score could be found when the side of the lesions was taken into account. The average number of errors on the total test and for each category of turn type for each type of lesion are listed in Table 2.

A one-way analysis of variance showed a trend towards differences in total error score between the four groups, but this trend did not reach statistical significance [F(3, 46) = 2.61, p < .06]. Analysis of the different turn types separately only showed a significant difference for the half rotation turn errors between the four groups [F(3, 47) = 3.51, p < .05]. Newman-Keuls post hoc analyses comparing means revealed significant differences between the left parietal and both the left and right frontal groups and the right parietal group. A comparison of the error scores of males (n = 37i and females (n = l3), regardless of lesion,

TAH1.E I Subject Variables for Each Lesion Group: Mean (SD)

Age“ Educatm”

1s 5 ( I X.0) 10.x (2.5) 76.X (12.7) 10.2 (1.6) 3x.x (I 5.2) 10.9 (2.8) 4l.h(lh.h) 11.8 (2.1)

7

TABLE 2 Average Number of Errors on the Total Test and for Each Turn Type According to

Lesion Group: Mean (SD)

Lesion Total Error

Score Half-Rotation

Errors Full-Rotation

Errors

Left frontal 2.2 (2.5) 0.2 (0.41 0.5 (I .O) 1.5 (1.5) Right frontal I .4 (2.9) 0.2 (0.6) 0.3 (0.7) 0.9 (I 3) Leti parietal 6.0 (7.7) I.1 (I.91 2.5 (3.2) 2.4 (3.1) Right parietal 4.5 (3.41 0.2 (0 4, 0.9 (1.2) 3.4 (2.7)

showed no significant difference for the total error score and for the error scores of the different turn types as a function of sex of subject.

The results confirm the hypothesis that patients with parietal lesions make more errors on the Money Road-Map Test than do patients with frontal lesions. Further analysis of this finding by using the proposed division in three turn types shows that the difference is predominantly made by the errors for half rotation turns and the full rotation turns. Errors pre- dominate in turns where the performance requires mental rotation over and above normal left-right discrimination.

When the frontal and parietal groups are further divided by left or right hemispheric localisation of the lesions, the differences in total error score are no longer significant, and our second hypothesis, namely a lower no-return error score in patients with right parietal as opposed to patients with left parietal lesions was not statistically confirmed.

Our findings do not support the suggestion of Butters et al. (1972). in that the high error score of their left frontal group reflected the test’s conceptual demands for making mental spatial rotations. Our left frontal group showed a relatively low error score as opposed to both parietal groups. Moreover, the frontal groups distinguished themselves from the parietal groups by significantly lower error scores in turns where mental rotation was involved. The results of our study show evidence for a parietal involvement of mental rotation skill, although a right hemispheric predominance for this skill could not be confirmed. It must be stressed however, that these results were obtained in a selected sample of patients, and that several remarks have to be made to allow for a critical interpretation of the results. First, all patients suffered from brain lesions that were macrostructurally confined to either left frontal, right frontal, left parietal or right parietal lobe, as evidenced by CT scans. Given the limits of computerized tomography, microstructural or nonmorphological brain damage outside the specified region cannot be excluded. Second, we have no data on the intellectual abilities of the patients, or the intellectual comparability of the groups. However, the level of education as expressed in years of schooling is highest in the poorly performing parietal groups, although statistical analysis shows no significant difference in educational level between the groups.

In view of these remarks, we conclude that the Money Road-Map Test can be a useful instrument in the differentiation of predominantly frontal versus predominantly parietal involvement in a restricted number of cases. The proposed division in turn types is not essential for this differentiation, but it can offer additional support for a possible parietal involvement if the high number of errors on turns requiring a mental spatial rotation is in contrast with a relatively normal performance in left-right discrimination on turns requiring no mental rotation.

Finally, we also agree with the comment of Resnick ( 1993) that gender differences in mental rotation skill are of limited practical value, except for the extremes, due to the large

8 G. Vingerhoets. E. lmtnoo. and S. Bauwens

variability of this cognitive skill in both sexes. A comparison of male and female performance in our sample, regardless of the lesion, found no significant differences in error score as a function of sex.

CONCLUSION

Presenting the Money Road-Map Test performance as a unitary measure would disregard the fact that at least two different cognitive processes, namely left-right discrimination and mental spatial rotation, are involved. In a first experiment we showed that the accuracy and the speed of the left-right decision process differs significantly with the degree of mental spatial rotation required. A division of the MRMT-turns in three categories (absent, moderate, and high degree of mental rotation) was proposed. That mental rotation was, indeed, funda- mentally involved was suggested by identical gender differences for turns requiring mental rotation as could be predicted on the basis of research on mental rotation skill with other, more classic, mental rotation tasks.

In a second study, the clinical relevance of this proposal was evaluated in a number of patients with neuroradiologically confirmed focal brain lesions. The Money Road-Map Test performance of these subjects showed that the patients with predominantly parietal lesions performed significantly worse than the patients with predominantly frontal lesions. A more detailed analysis with the division of turn types showed that the significant group difference in total error score was predominantly due to the error scores of turns requiring mental spatial rotation. The question remains whether the qualifying factor is the mental spatial rotation task itself, or if it is the superposition of mental rotation on a task of left-right discrimination. More research is needed to corroborate and clarify these findings. The turn types analysis did not ot’fer a diagnostic contribution to the lateralization of the lesions.

REFERENCES

Butters. N.. Soeldner. C., & brdio, P. (1972~. Comparlwn of parietal and frontal lobe spatial deficits in man:

Extrapersonal v%. personal (egocentric) space. t’rrc~eptual artd Motor Skiffs. 34, 27-34. Corballis, M. C., & Sergent. J. (1989). Hemispherw specialisation for mental rotation. Cortex, 25, 15-25. Damasio, H., & Damasio, R. D. (1989). Lesion anulws in neuropsychology. New York: Oxford University Press.

Deutsch, G., Bourbon, W. T., Papanicolaou, A. C.. & Eisenberg, H. M. (1988). Visuospatial tasks compared via activation of regional cerebral blood flow. Neurop.sw.holo~ia. 26. 445452.

Dltunno, P. L., & Mann, V. A. (1990). Right hemisphere hpecialisatwn for mental rotation in normals and brain damaged subjects. Conex, 26, 177-l 88.

Flicker, C., Ferris, S. H., Crook, T.. Reisberg, B., (L Hartuh. K. T (I 9X8). Equivalent spatial-rotation deficits in nor-

mal aging and Alzheimer’s disease. Journal of C(rnr~x~/ md Erprrimenrrrl Neuropsychology, 10, 387-399. Gallagher, S. A., & Johnson, E. S. (19Y2). The elfect of time Ilmits on performance of mental rotation by gifted

adolescents. G&d Child Quarterly, 36. 1% 22

Kerns. K. A., & Berenbaum. S. A. (1991) Sex dlft’crcnce\ In spatial ability in children. Behavior Genetics, 21, 383-396.

Lezak. M. D. (1983). Neuropsycholopxf (2.s.w~wwnt (2nd ed ). New York: Oxford University Press. Money. I.. Alexander, D., & Walker, H. T ( IYhSi UWU~J/. A stundardizrd road-map test of direction sense.

Baltimore: Johns Hopkins Press. Ratcliff, G., & Newcombe, F. (1973). Spatial orienratwn I” man Effects of left, right, and bilateral posterior cere-

bral lesions. Journul of Neurology, Neurosurgr~, und I’\vchuu~. 36, 448454. Resnick, S. M. (1993). Sex differences in mental rocarwn~: An effect of time Ilmits? Brain and Cognition, 21,

71-79. Roeltgen, I). P, Sevush, S.. & Hellman. K. M. ( 19X 7) l’urc Gerstmnnn‘s syndrome from a focal lesion. Archives of

NeuroL,,qy. 40, 4h- 47

Rosier. F., Schumacher, G., & Sojka. B. ( 1990). What the bram reveals when it thinks: Event-related potentials dur-

ing mental rotation and mental arithmetic. German Journal of Psychology, 14, 185-203. Strub. R. L.. & Geschwind, N. (1983). Localisation in Gerstmann syndrome. In A. Kertesz (Ed.), Localisafion in

neuropsychology. New York: Academic Press.

Thomas, H., & Kail, R. (1991). Sex differences m speed of mental rotation and the X-linked genetic hypothesis. Intelligence, 15. 11-32.

Documents

Money Road