pollatsek1981

BRAIN AND LANGUAGE 14, 174-180 (1981)
Asymmetries in the Perceptual Span for Israeli Readers
ALEXANDER POLLATSEK, SHMUEL BOLOZKY,
ARNOLD D. WELL, AND KEITH RAYNER
University of Massachusetts
Native Israeli readers read Hebrew and English text as their eye movements
were monitored. A window of text moved in synchrony with their eye movements
and the window was either symmetrical about the fixation point or offset to the
left or right. When subjects were reading Hebrew, the perceptual span was
asymmetric to the left and when they were reading English it was asymmetric
to the right. The results point out the importance of attentional factors in reading.
A great deal of research has confirmed that for right-handed subjects,
individual words are processed more efficiently when presented in the
right visual field (to the right of a central fixation location) than in the
left visual field. Early explanations of this asymmetry centered oh scan-
ning habits that result from experience with reading (Heron, 1957; Mish-
kin & Forgays, 1952). Inherent in much of the recent research on the
topic, however, is the assumption that the processing differences are due
to a functional asymmetry of the brain (Hecaen & Albert, 1978). Ac-
cording to this position, the left hemisphere is more specialized for verbal
processing and the right hemisphere is more specialized for spatial pro-
cessing, so that words are better recognized when presented in the right
visual field and thus initially received by the left or language-specialized
hemisphere.
The scanning explanation predicts that native readers of Hebrew
should show a left-visual-field superiority for words since the direction
of reading is from right to left. However, readers of Hebrew, like readers
of left-to-right languages, show a marked right-visual-field advantage for
the recognition of individual words (Orbach, 1967; Barton, Goodglass,
& Shai, 1956; Carmon, Nachson, & Starinsky, 1976; Silverberg, Bentin,
This research was supported by Grant HD12727 from the National Institute of Child
Health and Human Development (Keith Rayner, principal investigator). The authors thank
Jim Bertera and Robert Morrison for their assistance in conducting the study. Requests
for reprints should be addressed to Alexander Pollatsek, Department of Psychology,
University of Massachusetts, Amherst, MA 01003.
174
0093-934Xl81/050174-07$02.00/O
Copyright 0 1981 by Academic Press. Inc.
All rights of reproduction in any form reserved.

ASYMMETRIES IN PERCEPTUAL SPAN
175
Gaziel, Obler, & Albert, 1979). Thus, it has generally been concluded
that although scanning habits may have some influence on perceptual
asymmetries, there is an overriding effect of left-hemisphere superiority
for reading tasks (Jonides, 1979).
It is not clear, however, to what extent conclusions can be made about
the reading of text from studies in which individual words are briefly
displayed to the left or right visual field. Experiments (McConkie &
Rayner, 1976; Rayner, Well, & Pollatsek, 1980) with readers of English
text have confirmed that the perceptual span (the area of text from which
useful information is extracted during a fixation) is asymmetric, with
little information obtained from the left of the fixation point. In these
experiments, eye movement information was monitored and fed into a
computer controlling a cathode-ray tube (CRT) from which the subject
was reading. Changes were made on the CRT on the basis of the location
of the reader’s gaze. For example, a passage of mutilated text was initially
presented on the CRT with every letter from the original text replaced
by an X. However, whenever the reader fixated, a region around the
fixation point changed into readable test. This “window” area moved
in synchrony with the eye movement so that wherever the reader fixated,
the real text was exposed, but everywhere outside the window area the
mutilated text remained. By varying how far the window extends to the
left and right of fixation, it has been possible to determine the extent to
which the perceptual span in reading is asymmetric. The data suggest
that English readers show no difference in performance between (a) a
symmetric window extending 14 characters to the left of fixation and 14
characters to the right of fixation and (b) an asymmetric window ex-
tending 14 characters to the right of fixation but only 4 characters to the
left. On the other hand, if the window extends 14 characters to the left
of the fixation point but only 4 characters to the right, the reading per-
formance of English readers was considerably disrupted.
No experiments dealing with the characteristics of the perceptual span
for readers of Hebrew text have been reported, although there have been
suggestions that the direction of reading and hemispheric specialization
may be important for Hebrew readers (Albert, 1975). If the perceptual
span when reading text is determined by the same factors that are re-
sponsible for asymmetries when processing individual words (presumably
hemispheric specialization), then the perceptual span should be asym-
metric to the right. On the other hand, if the asymmetry of the perceptual
span for readers of English text is due primarily to attentional consid-
erations related to the pattern of eye movements, then the perceptual
span for readers of Hebrew text should be asymmetric to the left. In the
experiments reported here, the technique (Rayner et al., 1980) used
previously to investigate the asymmetry of the perceptual span for Eng-
lish readers was employed to determine if the perceptual span of Israeli

176
POLLATSEK ET AL.
readers is asymmetric to the left or right or is possibly symmetric due
to the conflict between the direction of scanning and hemispheric
specialization.
Israeli readers who were also fluent in English were asked to read
Hebrew sentences and English sentences presented on a CRT as their
eye movements were monitored. The window area around a fixation
point was either symmetric, extending 14 characters both left and right
of fixation, or asymmetric so that it extended either 14 characters left
and 4 right of fixation or 4 left and 14 right of fixation.
METHOD
Subjects
Six native Israeli subjects participated in the study. All were bilingual and the amount
of experience they had reading English varied from 3 to 29 years. They had all received
instruction in reading English beginning in at least the fifth year of school. All of the
subjects were right-handed and none of them required corrective lenses for reading. The
mean age of the subjects was 30 (range = 15-39 years) and two of them were female.
Apparatus and Procedure
Eye movements were recorded with a dual Purkinje eye tracker (Stanford Research
Institute) that was interfaced with a Hewlett-Packard 2100 computer. The eye tracker has
a resolution of 10 arcmin, and the output is linear over the visual angle (14 deg) occupied
by the sentences. Subjects’ heads were fixed by a bite bar. The subject’s eye was 46 cm
from the CRT used to present the sentences; three characters equaled 1 deg of visual
angle. Details of the apparatus have been described by Rayner et al. (1980).
At the beginning of the experiment each subject read some warm-up sentences with the
window offset either to the left or right of fixation. Following the warm-up sentences, each
subject read 16 Hebrew sentences in each of the 3 experimental conditions. Sentences
were read in blocks of 8 with the window either being symmetrical around the fixation
point, asymmetric to the right or asymmetric to the left. Subjects returned to the laboratory
on another day and read 48 English sentences, 16 in each of the conditions in the same
manner as the Hebrew sentences had been read. The English sentences were similar in
length and structure to English translations of the Hebrew sentences. For both Hebrew
and English sentences, the order of the conditions and the sentences read were counter-
balanced across subjects.
Subjects were instructed to read each sentence and then report the sentence to the
experimenter. They were instructed to report the sentence verbatim or to paraphrase it.
RESULTS AND DISCUSSION
With Hebrew text, reading performance (See Table 1 and Figure 1)
did not differ between the symmetric condition and the asymmetric con-
dition in which the window was shifted to the left. Conversely, when
subjects read English text, their performance was similar to that of native
English readers in that the symmetric condition did not differ from the
asymmetric condition in which the window was shifted to the right. As
can be seen in Table 1, the Israeli subjects read English (in the symmetric
and asymmetric right conditions) at the rate of 230 wpm (words per

ASYMMETRIES IN PERCEPTUAL SPAN
177
TABLE 1
EFFECTIVE READING RATES IN WORDS PER MINUTE FOR THE ISRAELI SUBJECTS READING
HEBREW SENTENCES AND ENGLISH SENTENCE< COMPARED TO AMERICAN SUBJECTS
READING COMPARABLE ENGLISH SENTENCES
Window
condition
Israeli subjects
Hebrew English English speaking
subjects
14-14 286 233 350
14-4 282 131 218
4-14 185 221 336
minute). Native English-speaking subjects’ typical reading rates are be-
tween 320 and 350 wpm on sentences of similar length and complexity.
We assume that the slower reading rate for the Israeli subjects on English
sentences is because English is not their native language. However, it
is instructive to note that for all of the variables shown in Table 1 and
Figure 1, the window offset had the same effect as it did for English
readers reading English. For both types of text, the asymmetric condition
in which the window was shifted in the direction opposite to that of
reading resulted in marked decrements in reading behavior.
-Hebrew
.i ‘%j :------r;,:
2
Asymmtrlc Symmetric Asymmatric
Left Right
FIG. 1. Mean saccade length, mean fixation duration, and number of fixations for
Hebrew and English text.

178 POLLATSEK ET AL.
When reading Hebrew, performance m the 14L-4R condition was
superior to that in the 4L-14R condition for each of the six subjects with
the exception of a reversal for a single subject on the fixation duration
measure. For reading rate, mean saccade length and mean number of
fixations per line, the results were highly significant, t(5) = 4.10, 7.45,
and 4.61, respectively, p < .Ol, whereas for average fixation duration,
the difference was not significant, t(5) = 1.26, p > .20. When reading
English, performance in the 4L-14R condition was superior to that in
the 14L-4R condition for each of the six subjects, with the exception
of a reversal for a single subject on the fixation duration measure. For
mean saccade length and mean number of fixations per line, the differ-
ences were highly significant, t(5) = 3.39 and 4.04, respectively, p <
.02, while for reading rate and mean fixation duration the results failed
to reach conventional levels of significance, t(5) = 2.39 and 2.52, re-
spectively, .05 < p < .10. However, this reduced level of significance
for reading rate was due to one subject who had a much larger difference
than the others which inflated the error term. If this subject who showed
the largest asymmetry (a difference of 292 wpm vs. an average difference
of 57 wpm for the other five subjects) is removed from the analysis, then
the difference in reading rate for the other five subjects is highly signif-
icant, t(4) = 5.16, p < .Ol.
These results provide an unambiguous demonstration that during the
reading of meaningful text, the direction of reading (and not hemispheric
specialization) primarily determines the asymmetry of the perceptual
span. For each of the six bilingual subjects, the perceptual span was
asymmetric to the left when Hebrew was read and asymmetric to the
right when English was read.
It is interesting to note that Hebrew varies structurally and ortho-
graphically from English in some important ways that are relevant to our
experiment. In Hebrew, many function words are clitic, i.e., are attached
like prefixes or suffixes to content words. Furthermore, unlike English,
not all vowels are represented in Hebrew orthography. The net effect
of these differences is that Hebrew sentences normally contain fewer
words than their English counterparts. In our case, for example, the
Hebrew sentences were translations of English sentences, and the He-
brew sentences were shorter than the English versions by approximately
1.3 words per sentence. Thus while the Israeli readers reading Hebrew
are markedly slower than American readers reading English (see Table
l), when measured by words per minute, this may be accounted for by
the above structural and orthographic differences. As a quick check that
there was nothing abnormally slow about our Hebrew readers, we com-
puted the reading rate in Hebrew based on the number of words contained
in the English translations of the Hebrew sentences. Using this measure,
the average reading rate for our native Israeli subjects reading Hebrew