Ho. Karnath, SPATIAL LIMITATION OF EYE-MOVEMENTS DURING OCULAR EXPLORATION OF SIMPLE LINE-DRAWINGS IN NEGLECT SYNDROME, Cortex, 30(2), 1994, pp. 319-330
The eye movement behaviour of a patient suffering from a right basal g
anglia infarction with left-sided neglect but without any visual field
defects was investigated during the ocular exploration of simple line
drawings. The eye movements were registered by means of an i.r. light
technique. Each line drawing consisted of different figural elements
located in the centre and both the left and the right half of the pict
ure. In each case, only the contextual connection of the left and righ
t elements in a drawing allowed the spectator to describe the whole sc
ene consistently and to perceive the correct theme of the drawing. The
drawings fell into two categories. The cognitive impact of the elemen
ts in the drawings' centre was varied by ''pointing'' to the elements
located in the left and right halves with a different strength of conn
ection. When exploring the two types of drawings (weak vs. strong conn
ective elements in the centre) the patient showed a similar eye moveme
nt pattern, exploring exclusively the right halves of the drawings. Ir
respective of the cognitive impact of the drawing's central elements i
n ''pointing'' towards supplementary information in the picture's left
half, exploration of this half took place in neither case. A striking
difference between the two categories was, however, found concerning
the patient's ability to recognize the general context, i.e. to descri
be the correct theme of the whole drawing. While the patient could not
correctly depict any of the scenes from the drawings with weak connec
tive elements in the centre, he was easily capable of properly describ
ing the themes from the group of drawings with strong connective eleme
nts, which implies that he must have analysed and perceived the figura
l elements of both halves of the picture. Different possibilities are
discussed to explain the similarity of the patient's exploratory eye m
ovements but discrepancy in his verbal responses when dealing with the
two different types of drawings.