Visual Scanning and Matching Dysfunction in Brain-Damaged Patients with Drawing Impairment

VISUAL SCANNING AND MATCHING DYSFUNCTION IN BRAIN-DAMAGED PATIENTS WITH DRAWING IMPAIRMENT I

Teodoro Belleza, Maurice Rappaport, H. Kenneth Hopkins and Karyl Hall (Langley Porter Neuropsychiatric Institute, University of California, San Francisco, California)

BACKGROUND

Kinsbourne ( 197 6) wrote that "the most common and most exhaustively studied performance· deficit referable to cerebral disease is the inability to copy simple line drawings." Drawing ability can be impaired with injury to one or both cerebral hemispheres (Benton, 1962; Piercy et al., 1960). Several studies have investigated the functional basis of the impairment - whether it results from sensory or motor disorders, or from perceptual or execut1ve disorders - and related their findings to the hemispheric side of injury (Arrigoni and De Renzi, 1964; Benson and Barton, 1970; Benton, 1967, 1973; Warrington et al., 1966). While some authors have proposed that disordered visual perception underlies failure on drawing tasks (Dee, 1970; Dee and Benton, 1970; Poeck et al., 1973), others have suggested that the basis of drawing impairment varies with the laterality of the injury a visual perceptual disorder primarily of a spatial type being associated with right-sided lesions and executive disorders with left-sided lesions (Gainotti and Tiacci, 1970; Hecaen and Assal, 1970; Kinsbourne, 1976; Warrington et al., 1966; Warrington, 1969). Several studies have reported that, in some cases, abnormal visual exploration underlies disorders of visual perception. Most prominent of these are investigations of the relationship between the syndrome of unilateral inattention and disordered perception of spatial relations (Chedru et al., 1973; Costa et al., 1969; De Renzi et al., 1970; Gainotti and Tiacci, 1971; Oxbury et al., 1974). Abnormal visual exploration patterns have been observed in brain-damaged subjects with ( 1) disorders of visual recognition such as simultanagnosia (Karpov et al., 1968; Luria et al., 1963; Tyler, 1 This work was supported by a Biomedical Research Support Grant from the Langley Porter Neuropsychiatric Institute.

Cortex (1979) 15, 19-36.

20

T. Belleza, M. Rappaport, H. Kenneth and K. Hall

1968); (2) drawing impairment (Garron and Cheifetz, 1967) and (3) aphasia (Kirshner and Sidman, 1972; Tyler, 1969). From a review of the considerable literature on drawing disorders it becomes clear that, because of the complex of functions that comprise a drawing task, assessment of the functional basis of such disorders must consider several factors in addition to locus of brain injury. More evident are disorders of motor function such as paresis, tremor, and ataxia, and disorders of communication such as the aphasias. Less evident but equally important are sensory losses such as hemianopia and amblyopia; disorders of motor planning ability, and other visual receptive disorders such as inattention, inadequate acquisition, impaired recognition and defective retention of visual information. PURPOSE

This study was undertaken to examine visual receptive disorders in brain-damaged subjects with drawing impairment demonstrated by the Bender-Gestalt Visual-Motor Test (Bender, 1938). Specifically, the aims were to study disorders of visual recognition by assessing the ability to match Bender figures, and disorders in the acquisition of visual information by analyzing scanning (eye movements and fixation) patterns; to determine whether specific errors made on the Bender-Gestals Test are related to impaired visual recognition and to specific aberrations in scanning behavior, independently of errors that could be attributed to defects in motor performance, and to examine the influence of the hemispheric locus of injury on visual receptive disorders and on drawing impairment.

MATERIALS AND METHOD

Subjects

Data were collected from 20 brain-damaged patients and 7 normal controls. Patients were selected from those who had been discharged from inpatient services and admitted to the outpatient program of the Head Injury Unit of the Department of Physical Medicine and Rehabilitation, Santa Clara Valley Medical Center (San Jose, California). The criteria for selection of patients were that they had: ( 1) evidence of brain damage determined at surgery or radiologically and by neurological and neuropsychological evaluation, (2) a total error score of 2 or greater on the Bender Gestalt Visual-Motor Test, (3) visual acuity of at least 20/50 in the right eye, (4) no gross oculomotor impairment, (5) were able to comprehend simple test instructions, (6) right-handed, and (7) had no previous history of psychosis. Normal control were volunteers from the staff at the hospital. Of the 20 patients, 6 had injury primarily to the left hemisphere (3 CVA,

Visual scanning and matching dysfunction

21

3 trauma), 6 had injury primarily to the right ( 4 CVA, 2 trauma), and 8 had bilateral injuries (3 anoxia, 5 trauma). Table I lists other pertinent cliQical findings on each brain-damaged subject including his/her score on the Disability Rating Scale (Rapport et al., 1977). This scale, based largely on the works of Teasdale and Jennett (1974), Scranton et al. (1970) and on the special needs of the treatment staff of the rehabilitation unit, is used to assess the physical, functional, and mental status of brain-damaged patients at all stages from the level of coma to complete recovery. Ratings are based on simple motor acts and responses. Specific ratings include eye opening response; best verbal response; best motor response; cognitive awareness with respect to toileting, feeding, and grooming; level of functioning in terms of degree of dependence on others; and psychosocial functioning as reflected in the level of employability. Analysis of mean differences between the three brain-damaged g~m;p~s in terms of age, days from onset of injury to testing and disability rating revealed no significant differences.

Procedure Bendes Gestalt Visual-Motor Test This test consists of reproducing nine geometric designs. Scoring criteria employed were those defined by Koppitz (1963 ). In addition to the total error score, subtotal scores were tallied for errors of distortion of shape, rotation and integration.

Visual Matching Test Bender figures A, 4 and 5 were employed as stimulus figures. The subject was presented a 3" X 5" card showing a stimulus figure. Below this stimulus card was arranged a row of five cards, four of which showed the stimulus figure in varying degrees of distortion of shape; a fifth was the correct match. The subject was asked to point to this correct match. Once a choice was made a second row of cards was presented. These showed the stimulus figure in 0°, 45°, 90°, 135", and 180" rotations. Subsequent to the subject's response, a third row of cards was presented. In addition to the correct match there were four cards which showed the stimulus figure in varying degrees of integration error - that is, the contiguous components of the stimulus figure were represented as either overlapping or non-contiguous. This procedure was repeated for the remaining two Bender figures so that in all 9 judgements were made. The order of cards in a row as well as the sequence of rows presented were randomized for each subject. Total error scores were tallied. Figure 1 shows examples of stimuli used.

Visual Exploration Test A Wide Angle Laboratory Eye Movement Recorder (Model V-1166, Polymetric Co.) using a 16 mm motion picture camera recorded fixations and saccades of the subject's right eye as he sequentially viewed the following - a calibration slide, a line drawing from the Thematic Aperception Test, Bender figure A, a photograph of the ocean floor, Bender figure 4, a photograph of two men working on a bench, and Bender figure 5. Non-Bender slides were used to control for

M

20

2

26

22

22

19

24

41

Disability rating Visual field defect

M

19

1

M

18

Bilateral

F

17

108

M

16

Bilateral

342

21

M

15

Bilateral

838

41

F

511

502

21

46

M

11

14

Bilateral

330

F

10

F

Right

590

55 38

M

9

M

Right

348

28

F

8

12 Trauma

Right

459 803

61

M

7

13

CVA

Right

501

27

M

CVA

796

978

638

529

Bilateral

Bilateral

Bilateral

Bilateral

Right

Right

Left

Left

Trauma

Anoxia

Trauma

Trauma

Anoxia

Trauma

Anoxia

Trauma

CVA

CVA

CVA

Trauma

Trauma

CVA

Trauma

471

Left

40

786

M

19

5 6

Left

188

49

Trauma

CVA

M

Left

423

Left

33

114

M

F

2

54

Days post Hemisphere Et"101 onset involved ogy

4

F

1

Age

3

Sex

Subj. No.

!AISL.t. 1

Right VFD; anomia

Expressive aphasia

Right VFD

Right VFD'; right hemiplegia

Right hemiparesis; expressive aphasia

Significant neurologic signs

Ataxia

Frontal, parietal, occipital

-

Frontal, parietal, occipital

Frontal, parietal, occipital

-

Right VFD

-

Left neglect; dressing apraxia

Right hemiparesis

Left VFD; left neglect

Frontal, temporal, parietal, Right hemiparesis occipital

-

Dysarthria

Left VFD; left hemiplegia; left neglect

Parietal, occipital Frontal, parietal

Left VFD; left hemiparesis

Left VFD; left hemiplegia

Left VFD; left hemiplegia; left neglect

Dressing apraxia; left neglect

Left hemiparesis

Internal carotid artery

Middle cerebral artery

Internal carotid artery

Middle cerebral artery

Parietal, occipital

Temporal, parietal, occipital Right VFD; alexia; right neglect

Middle cerebral artery

Frontal, parietal, temporal

Posterior cerebral artery

Frontal, parietal, occipital

Middle cerebral artery

Primary locus

Summary of Pertinent Clinical Findings in Brain-Damaged Patients

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Visual scanning and matching dysfunction

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DISTORTION OF SHAPE

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Example of visual matching tasks using Bender figure A.

initial fixation bias. These were projected onto a rear projection screen ( 8" X 8") 14" from the eyes. This stimulus field subtended an angle of 33° and each Bender figure subtended the central 19° of this field. The only instructions given the subject were that he was going to be shown some pictures and all he had to do was look at them. Each figure was presented for 10 seconds and recording speed was set at 10 frames per second. For the purposes of this analysis, the stimulus field was divided into a 7 X 7 cell matrix. It was assumed that the most informative portion of the Bender figures was the point of tangent between the two components of each figure. This assumption was validated by independent judgements of ten normal raters who were not included in the study. The Bender figures were projected in such a way that this point of tangent occupied the central cell of the matrix. Modifications of the Eye Movement Recorder enabled landmarks to be reflected from the subject's pupil to permit identification of the X and Y coordinates of the gaze relative to the stimulus field. From a frame by frame analysis of the motion picture record of the inspection of each Bender figure, the following parameters were obtained: (1) the location of the first fixation, (2) total number of fixations, (3) mean fixation duration, ( 4) time taken to find the most informative cell, (5) total time spent on the most informative cell, ( 6) the exploration time difference between left and right peripheral fields. The last parameter was obtained by separately summing the durations of fixations to the left and to the right of the central column of cells in the matrix and recording the difference between the sums. Since these left and right visual areas are peripheral to this central column the term "peripheral fields" is used. Finally, each subject's sequence of fixations was plotted. The sequence of the three tests was randomized for each subject.

24

T. Belleza, M. Rappaport, H. Kenneth and K. Hall

RESULTS

To examine visual receptive disorders in brain-damaged patients with drawing impairment on the Bender, their performance on the Visual Matching and Visual Exploration tests was compared to that of normals. These comparisons are summarized in Table II. Normals performed perfectly on the Visual Matching test whereas patients as a group averaged 1.4 errors. The difference in means approached significance (p < .10). Significant differences in Visual Exploration performance were obtained between braindamaged patients with drawing impairment and normals. Six out of seven normal controls located the central cell, rated as containing the most information, by their first fixation; the seventh located this cell by the second fixation. In contrast, immediate fixation of the most informative cell was shown by four (of 20) patients on figure A and by three on figure 4. 2 In addition as shown in Table II, patients had significantly more fixations than normals (p < .001 ); had significantly shorter fixation durations p < .001); and spent significantly less time on the most informative cell (p < .025). Table III presents coefficients of correlation between Bender Gestalt Visual-Motor Test, the Visual Matching, and the Visual Exploration Tests for brain-damaged patients with drawing impairment. It can be seen that performance on all three tests are significantly correlated in many instances. Bender Gestalt total score was significantly correlated with Visual Matching (r = .806, p < .001) and with the following Visual Exploration scores, Time Taken to Find the Most Informative Cell (r = .546, p < .025) and Total Number of Fixations (r = -.485, p < .025). Errors of distortion on the Bender test were not found to be correlated with Visual Matching nor with Visual Exploration scores. However, rotation errors were significantly correlated with integration errors (r = .565, p < .025), with Visual Matching performance (r = .822, p < .001 ), and with Time Taken to Find the Most Informative Cell (r = .586, p < .005), Total Number of Fixations (r = .488, p < .05) and Mean Fixation Duration (r = .483, p < .005). Integration errors were correlated with Visual Matching (r = .616, p < .005), Time Taken to Find the Most Informative Cell (r = .560, p < .025) and Time Spent on the Most Informative Cell (r = .475, p < .05). Visual Matching performance was significantly correlated with all the Visual Exploration measures except Mean Fixation Duration. Comparisons of Bender Gestalt Test and Visual Matching Test scores between brain-damaged patients grouped according to the primary locus of 2 Data from figure 5 is not reported since technical problems prevented analysis of records of visual inspections of this figure from four patients and two normals. Because of this, each subject's raw scores were averaged from figures A and 4. However, for those subjects with complete data similar results were obtained across the three figures.

Normals

All patients

Groups

Mean S.D. N Mean S.D. N t p

.10

1.40 1.67 20 0.0 0.0 7 1.976

Visual matching errors

1.43 2.11 20 0.08 0.07 7 1.625 n.s.

Time taken to locate most informative cell (sec.) 22.03 3.30 20 15.64 1.22 7 4.807 .001

Total fixations

~----

0.40 0.10 20 0.60 0.06 7 -4.889 .001

Mean fixation duration (sec.)

Visual exploration

1.66 1.06 20 2.81 0.77 7 -2.536 .025

Time spent on most informative cell (sec.)

Visual Matching and Visual Exploration Scores in Brain-Dam.aged and Normal Subjects

TABLE II

3.37 3.04 20 1.12 0.61 7 1.873 n.s.

Exploration time difference between peripheral fields (sec.)

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-.405

-.537**

-.172

-.485** -.242 -.488*

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.655*** -.530** .612*** -.298 -.458 .363 -.809****

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E -.261 .053 -.294 -.475* -.477*

D .433 .167 .483* .120 .432

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* p < .05; ** p < .025; *** p < .005; *''** p < .001; N == 20 1 Visual Exploration scores: A - Time Taken to Locate Most Informative Cell; B - Total Fixations; C - Mean Fixation Duration; D - Time Spent on Most Informative Cell; E - Exploration Time Difference Between Peripheral Fields.

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TABLE III

Correlations between Tests for Brain-Damaged Patients

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Visual scanning and matching dysfunction

27

hemispheric injury are presented in Table IV. On the Bender, left braindamaged (LBD) patients made the least errors; right brain-damaged (RBD) patients made the most errors. This mean difference was significant ( t = -4.69, p < .002). Analysis of subtotal error scores revealed no difference in mean distortion errors between the two groups. However, significant differences between groups were obtained from comparisons of mean errors of rotation (t = -5.16, p < .002) and of mean errors of integration (t = -2.45, p < .05). LBD patients made no rotation errors and the least integration errors; RBD patients made the most rotation errors and the most integration errors. Bender scores of patients with bilateral injuries consistently fell between those of LBD and RBD patients. On the Visual Matching Test, LBD patients were consistently able to find the correct match. RBD patients committed the most errors. This mean difference was significant (t = -3.96, p < .01). As in the Bender, the mean Visual Matching score of those with bilateral injuries fell between those of the other two and was not significantly different from either. No significant differences in Visual Exploration scores were obtained between brain-damaged groups. Patients with disorders of spatial orientation demonstrated by various tests of perceptual or perceptual-motor function have been frequently observed to exhibit abnormal visual exploration patterns (Benton, 1969; Garron and Cheifetz, 1967; Tyler, 1968). Consequently, a further analysis was made to determine whether spatial errors on the Bender were related to impaired visual recognition and to specific aberrations in visual exploratory behavior. For each patient, subtotal Rotation and Integration error scores were combined since errors of these types generally reflect a disorder of dealing with spatial relationships. Combined error scores ranged from 0 to 12 with a median of 3. Patients were then divided into two groups. Group I was composed of 9 patients whose combined error scores were less than 3. Group II was composed of 11 patients whose combined scores were 3 or greater. Of the 9 Group I patients, 5 had primarily left hemisphere injury and 4 had bilateral injury. Of the 11 Group II patients, 1 had primarily left hemisphere injury, 6 had right hemisphere injury, and 4 had bilateral injury. Comparisons of Disability Ratings, Bender-Gestalt Total, Visual Matching and Visual Exploration scores between Group I and Group II patients are summarized in Table V. No difference in Disability Ratings was observed. However, as expected from correlational data, significant differences between groups were obtained from comparisons of Bender-Gestalt Total scores and of Visual Matching and Visual Exploration scores. Group I patients (those with combined Rotation and Integration error scores of less than 3) when compared to Group II patients (those with combined Rotation and Integration error scores of 3 or greater) performed better on the Bender-Gestalt Test (actually to be expected based upon how Groups I and II were

-3.955 .01 -2.451 .05 -5.161 .002

-0.177 n.s.

t p

Left vs. Right

S.D. N

-4.686 .002

1.38 1.51 8 1.63 1.06 8

1.25 1.67 8

1.88 1.73 8

5.38 3.02 8

Mean

Bilateral

S.D. N

2.83 1.60 6 3.67 1.86 6

3.50 1.52 6

2.33 1.63 6

10.17 2.71 6

Right hemisphere Mean

S.D. N

0.00 0.00 6 1.33 1.03 6

0.00 0.00 6

2.17 1.33 6

3.83 1.33 6

Left hemisphere

Mean

Visual Matching

Integration

Rotation

Distortion

Total

Patient groups

Bender Gestalt Visual-Motor Test

Comparisons of Bender Gestalt and Visual Matching Error Scores between Patient Groups with Different Primary Sites of Hemispheric lniury

TABLE IV

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-0.149 n.s. -3.508 .005

2.36 1.63 11

0.22 0.67 9

Visual Matching

-2.491 .05

2.41 2.48 11

0.23 0.15 9

1.008 n.s.

21.32 3.54 11

22.89 2.96 9

Time taken to locate most Total fixations · £ormatlve · m ce11

-1.298 n.s.

0.43 0.12 11

0.37 0.07 9

. Medan fit~ation ura Jon

Visual Exploration

1.872 .10

1.26 0.84 11

2.14 1.15 9

-2.303 .05

4.70 3.19 11

1.75 1.94 9

1 · Time spent . xp ~ration on most tlmeb difference . £ . m ormatlve cell penp . hetween er al fields

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' Group I patients were those whose combined Bender Rotation and Integration error scores were less than 3. Group II patients were those whose combined Bender Rotation and Integration error scores were 3 or greater. 2 Disability Rating.

p

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8.64 3.14 11

4.0 1.79 11

3.56 1.42 9

Group II Mean S.D. N

2

3.89 1.27 9

DR

Bender G s 1 T~::l t

Mean S.D. N

Group I

Patient groups

TABLE V

Comparisons of Bender Gestalt, Visual Matching and Visual Exploration Scores between Groups I and II Patients

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30

T. Belleza, M. Rappaport, H. Kenneth and K. Hall

established) and on the Visual Matching Test. On the Visual Exploration Test, Group I patients took significantly less time to locate the most informative cell (p < .05) and exhibited significantly less differences in time spent exploring the left and right peripheral fields (p < .05). Finally, Group I patients tended to spend more time on the most informative area of the Bender figures than did Group II patients, but the mean difference did not reach significance (t = 1.87, p < .10).

DISCUSSION

This study has indentified two visual receptive disorders associated with drawing impairment in brain-damaged patients. All patients who performed poorly on the Bender Gestalt Visual-Motor Test also showed abnormal eye movement patterns indicating impaired acquisition of visual information. Some of these patients showed a disorder of visual recognition in that they were unable to match Bender figures. Comparisons between brain-damaged and normal subjects The eye movement findings are of particular interest since it has been proposed that disordered visual perception underlies failure on drawing tasks (Dee, 1970; Dee and Benton, 1970). Neisser (1969) proposed that visual perception of an event is a product of a very selective and dynamic process which he called, "analysis-by-synthesis". During this process an extensive series of eye movements (fixations and saccades) serve to explore the visual stimulus bit by bit (analysis) and is the means by which a mental representation of that stimulus is constructed (synthesis). In this study, all braindamaged patients with drawing impairment showed abnormal scanning patterns. As compared to normals they had more fixations, shorter fixation durations, and spent less time on the most informative areas of the stimulus figures. Their scanning patterns were often asymmetric. The findings are consistent with those of Chedru et al. (1973) that visual search patterns of brain-damaged subjects were often unsystematic and irregular and that these subjects did not explore the left and right halves of visual space in identical fashion. These results support the interpretation that there is disordered visual perception in brain-damaged patients with drawing impairment. Correlations between tests Correlational analyses revealed significant intercorrelations between Bender performance, Visual Matching and Visual Exploration scores. This is reasonable since accurate copying of geometric designs requires competent sensory and perceptual functions integrated with intact motor functions.

Visual scanning and matching dysfunction

31

Perceptual function relies upon efficient acquisition of visual information through eye movements and fixations. More significant was the finding that spatial errors (Rotation and Integration) on the Bender test and not errors of shape distortion were correlated with impaired visual matching performance and with markedly abnormal scanning behavior. This suggests that errors of shape distortion may reflect errors related more to motor than to visual receptive difficulties. Group I vs. Group II

Related to the correlational findings were results obtained from comparisons of visual matching and visual exploration performance between Group I and Group II patients. Group I patients were those whose Bender reproductions indicated mild to no defects in spatial ability. Group II patients were those who exhibited moderate to severe defects in spatial ability. Group II patients had significantly higher Bender Gestalt total scores and made more Visual M!ltching errors. On the Visual Exploration test, Group II patients took longer to locate the most informative visual area, exhibited greater time differences in the exploration of the left and right peripheral fields and spent less time on the most informative visual areas. These deficits were associated with neurologic and neuropsychological signs of injury to posterior areas of the brain. These signs included moderate to severe hemi-inattention, visual field defects, sensory losses in either extremities and apraxia for dressing. Possible theoretical basis for findings

Visual perception is both a predictive and constructive process requiring the parallel processing of information by two distinct visual systems - focal vision and ambient vision. It is constructive in that bits of visual information sampled by focal vision during fixations are synthesized into an internal representation of an external visual stimulus. It is predictive in that in the initial stages of visual perception the brain forms an impression or a hypothesis of what is being seen. This hypothesis is formed from information acquired by a series of very brief fixations separated by large eye movements and from comparisons with stored past experiences. Only a few highly informative areas are sampled during this brief but extensive visual scan so that inputs from both ambient and focal vision become highly essential. Ambient vision enables detection of salient visual information peripheral to the area currently fixated. This initial stage is followed by a detailed elaboration of the initial impression. Scanning patterns are then modified so that eye movements are shorter and fixations are longer to enable focal inspection of detail (Antes, 1974; Bruner, 1957; Mackworth and Bruner, 1971).

32

T. Belleza, M. Rappaport, H. Kenneth and K. Hall

Ambient vision is subserved by a pathway other than the classical retino-geniculostriate pathway which subserves focal vision. Visual information is passed along this alternate pathway from the optic chiasm to the superior colliculus and other midbrain and brain stem structures and is projected onto the visual association areas. Trevarthen ( 197 4} and DennyBrown and Fischer ( 197 6} have proposed that ambient vision provides the spatial framework for perceived stimuli. This model attributes some visuospatial function to brain structures other than the posterior parietal lobes where spatial information is thought to be synthesized. Work by Mountcastle and his group is relevant here since it provides a functional link between the parietal lobes and the neural mechanisms involved in ambient vision. Specifically, they have identified in the inferior parietal lobule of the monkey separate groups of neurons which differentially fire when monkeys fixate objects of interest, when fixation is maintained and just prior to a saccade toward another object of interest. Yin and Mountcastle ( 1977) suggest that visual input from ambient vision activate the visuomotor mechanism in the parietal lobe which trigger shifts in visual attention. The role of the parietal lobe in enabling shifts in visual attention is emphasized by the extensive literature on the syndrome of unilateral neglect. Heilman and Watson ( 1977 a, 1977b) have observed that lesions of brain structures that particularly lesions in the comprise a "cortico-limbic-reticular" loop area of the inferior parietal lobe - produce a disorder of attention so that stimuli from the side contralateral to the lesion are either ignored upon unilateral stimulation or extinguished upon bilateral simultaneous stimulation. Most of the brain areas, such as the inferior parietal lobes, the superior colliculus and other limbic and brain stem structures, which Heilman and Watson regard as important in the induction of neglect, comprise the ambient vision pathway. Thus our results suggest that disorders of visual attention and deficits in dealing with spatial relations underlie impairment of drawing ability. These disorders of visual attention are reflected in inability to detect salient information peripheral to the fixation point and in asymmetric deployment of attention to the left and right peripheral fields. Neurologic and neuropsychological symptoms in these cases are associated with posterior brain injury. One may hypothesize that these disorders would result in an inability to form a preliminary hypothesis about the nature of a specific visual stimulus and/ or make it difficult to construct a spatially oriented internal representation of the stimulus.

Hemispheric locus of injury The test results in relation to locus of injury suggest a more disabling effect of right hemisphere injury on tasks requiring visual attention and

Visual scanning and matching dysfunction

33

visual perception. Of the 11 Group II patients, six had unilateral right hemisphere injuries, one had unilateral left hemisphere injuries and four had bilateral injuries. Of the four with bilateral injuries two had extensive right hemisphere involvement. Right brain-damaged (RBD) patients were most impaired on the Bender test, made the most errors of rotation and integration and were unable to match Bender figures. Left brain-damaged patients (LBD) were the least impaired on the Bender test, made no rotation errors, had the least integration errors and were able to match Bender figures. These results are consistent with those of Warrington et al. ( 1966) and Gainotti and Tiacci ( 1971) that reproductions of geometric designs by RBD patients are different from those by LBD patients. They propose that the functional basis of drawing impairment in right brain damage is different from that in left brain damage. The issue may be raised that the extent and severity of brain injury account for differences observed. RBD patients may have had more extensive lesions than LBD patients. Following this logic, one would expect patients with bilateral injuries to ·exhibit the most severe deficits since the etiology of their neurologic disorders (5 trauma, 3 anoxia) indicated that they had more diffuse brain damage. Examination of performance scores reveal a wide range of severity from very mild to severe impairment suggesting that what matters is what brain areas are injured and not how much is injured. Although there was no direct measure of the extent of brain damage, no differences between brain-damaged groups were found in comparisons of mean disability ratings based upon observations of physical, functional, and mental status. These ratings have been shown to be significantly correlated with measures of abnormalities of evoked brain responses recorded from brain-damaged patients (Rappaport et al., 1977) and which are thought to reflect the brain's ability to process sensory information. It should be kept in mind that patients included in this study were homogeneous with respect to their level of disability. On the 29-point Disability Rating Scale patient scores ranged from 2-6 (mild to moderate disability). Two limitations of the study restrict further interpretati on of the data regarding the influence of laterality of brain injury on visual cognitive performance. First is the inclusion of head trauma cases in the unilateral groups raising the possibility that impaired performance in these cases reflected undetected injury to contralateral sites. Second is the absence in the left hemisphere group of patients with documented evidence of damage to temporo-parietal areas associated with severe receptive aphasia. Benton ( 197 3) reported that the frequency and severity of visuoconstructive impairment measured by a block-building test, in receptive aphasics with left brain damage were the same as those in non-aphasics with right brain damage. Poeck et al. ( 197 3) found that LBD aphasics were inferior to LBD non-aphasics on the Benton Visual Retention Test and on the Gottschaldt Embedded

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T. Belleza, M. Rappaport, H. Kenneth and K. Hall

Figures Test. LBD aphasics were as impaired as RBD non-aphasics on both tests. They proposed that "there is a common underlying functional disturbance of the visuospatial type associated with the retro-rolandic part of both hemispheres." Tyler (1969) examined picture scanning behavior in 3 aphasic sub-groups anomies, motor (expressive) aphasics, and sensory (receptive) aphasics. Patients with only naming or word-finding defects showed scanning patterns similar to those of normals. Motor aphasics showed normal patterns during the initial 2-10 seconds of pictorial inspection and then reverted to abnormal patterns. Sensory aphasics showed markedly abnormal scanning patterns characterized by the inability to locate and fixate informative areas of the pictorial stimuli. These scanning patterns are strikingly similar to those shown by our brain-damaged patients with copying impairment and with defects in dealing with spatial information. It seems that in both left and right brain damage involvement of temporo-parietal (posterior) brain areas is essential in eliciting defective performance on visual-cognitive tasks. Further investigation of drawing impairment in RBD subjects, LBD expressive aphasics and LBD receptive aphasics and of the specific visual receptive disorders underlying copying impairment in these sub-groups is warranted. SuMMARY Visual matching and visual exploration were examined in 7 normal subjects and 20 brain-damaged patients with dra\Ying impairment measured by the Bender Gestalt Visual-Motor Test. Right brain-damaged patients made significantly more errors of rotation and integr:ation than left brain-damaged patients. Selected Bender figures were also used as stimuli for both visual matching and visual exploration tests. The ability to match Bender figures was found to be impaired in right but not left brain-damaged patients. All patients showed eye movement and fixation patterns different from those of normals. Patients essentially had more fixations and shorter fixation durations. Significant intercorrelations were found between the total Bender Gestalt score and visual matching and visual exploration scores. These findings indicate that visual matching and visual exploration measures can be used to evaluate perceptual impairment in individuals who do not have adequate motor responses or where impaired motor responses may confound interpretations about visual cognitive impairment.

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Teodoro Belleza, B.A., Maurice Rappaport, M.D., Ph.D., H. Kenneth Hopkins, M.S., Karyl Hall, M.A., Research Department, Agnews State Hospital, San Jose, California, 95114.