Visual-perceptual abilities in healthy controls, depressed patients, and schizophrenia patients

Department of Psychology, University of Waterloo, Ватерлоо, Ontario, Canada
Brain and Cognition (Impact Factor: 2.48). 09/2007; 64(3):257-64. DOI: 10.1016/j.bandc.2007.03.008
Source: PubMed
ABSTRACT
Previous studies have suggested a right hemineglect in schizophrenia, however few assessed possible visual-perceptual implication in this lateralized anomaly. A manual line bisection without (i.e., lines presented on their own) or with a local cueing paradigm (i.e., a number placed at one or both ends of the line) and the Motor-free Visual Perceptual Test-Vertical format (MVPT-V) were used to assess the visual-perceptual abilities of healthy controls, schizophrenia and depressed patients. Whereas healthy controls and depressed patients showed a non-significant leftward bias in manual line bisection, schizophrenia patients bisected significantly to the left of the true centre of the line. Interestingly, the pattern of performances in response to the local cueing paradigm was similar in depressed and schizophrenia patients such that both groups demonstrated a significant change in their bisection performance only in response to a cue placed at the right extremity of the line (control performance was modified by cues at either end of the line). Finally, in the MVPT-V, schizophrenia patients were impaired relative to the other two groups, especially in the spatial working memory and visual closure categories. These results suggest that: 1/a deficit towards the right hemifield, consistent with a mild form of right hemineglect, can be observed in schizophrenia; 2/lateralized anomalies could also be observed in depression using an appropriate tool such as manual line bisection; 3/performances in the MVPT-V suggested that a simple visual-perceptual deficit could not explain the lateralized anomaly observed in the manual line bisection, as it is the case in the hemineglect syndrome.

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Visual-perceptual abilities in healthy controls, depressed patients,
and schizophrenia patients
Ce
´
line Cave
´
zian
a,b,c,d
, James Danckert
e
,Je
´
ro
ˆ
me Lerond
a,b,c,d
, Jean Dale
´
ry
a,b,c,d
,
Thierry d’Amato
a,b,c,d
, Mohamed Saoud
a,b,c,d,
*
a
Universite
´
de Lyon, Lyon, F-69003, France
b
Universite
´
de Lyon 1, EA 4166, Lyon, F-69003, France
c
Center Hospitalier le Vinatier, F-69677 Bron Cedex, France
d
Institut Fe
´
de
´
ratif des Neurosciences de Lyon, Bron, F-69677, France
e
University of Waterloo, Department of Psychology, 200 University Avenue West, Waterloo, Ont., Canada N2L 3G1
Accepted 27 March 2007
Available online 22 May 2007
Abstract
Previous studies have suggested a right hemineglect in schizophrenia, however few assessed possible visual-perceptual implication in
this lateralized anomaly. A manual line bisection without (i.e., lines presented on their own) or with a local cueing paradigm (i.e., a num-
ber placed at one or both ends of the line) and the Motor-free Visual Perceptual Test—Vertical format (MVPT-V) were used to assess the
visual-perceptual abilities of healthy controls, schizophrenia and depressed patients. Whereas healthy controls and depressed patients
showed a non-significant leftward bias in manual line bisection, schizophrenia patients bisected significantly to the left of the true centre
of the line. Interestingly, the pattern of performances in response to the local cueing paradigm was similar in depressed and schizophrenia
patients such that both groups demonstrated a significant change in their bisection performance only in response to a cue placed at the
right extremity of the line (control performance was modified by cues at either end of the line). Finally, in the MVPT-V, schizophrenia
patients were impaired relative to the other two groups, especially in the spatial working memory and visual closure categories. These
results suggest that: 1/a deficit towards the right hemifield, consistent with a mild form of right hemineglect, can be observed in schizo-
phrenia; 2/lateralized anomalies could also be observed in depression using an appropriate tool such as manual line bisection; 3/perfor-
mances in the MVPT-V suggested that a simple visual-perceptual deficit could not explain the lateralized anomaly observed in the
manual line bisection, as it is the case in the hemineglect syndrome.
Ó 2007 Elsevier Inc. All rights reserved.
Keywords: Line bisection; Visual-perception; Schizophrenia; Depression
1. Introduction
A number of studies have proposed a subtle right hemi-
neglect to describe visuo-spatial anomalies towards the
right hemispace in schizophrenia (e.g., Posner, Early, Rei-
man, Pardo, & Dhawan, 1988). Hemineglect can be defined
as a failure to attend to stimuli presented in one hemispace,
the most marked examples of which are seen in patients
suffering parietal lesions (for review, Danckert & Fer ber,
2006; Heilman, Watson, & Valenstein, 2003). Several theo-
ries have been developed to explain hemineglect and almost
all agree with the idea that an impairment in basic visual-
perceptual processing (i.e., low level) cannot explain this
syndrome. Nevertheless, impairments in higher levels of
visual-perceptual processing (such as visual working mem-
ory) can be observed in theses patients (Ferber & Danckert,
2006; Malhotra et al., 2005). One way to assess visual-per-
ceptual abilities (at both low and higher levels) of stroke
patients is to use the Motor-free Visual Perception
Test—Vertical format (MVPT-V) (Mercier, Hebert, Cola -
russo, & Hammill, 1997). This test probes several
0278-2626/$ - see front matter Ó 2007 Elsevier Inc. All rights reserved.
doi:10.1016/j.bandc.2007.03.008
*
Corresponding author. Fax: +33 04 37 91 55 49.
E-mail address: mohamed.saoud@ch-le-vinatier.fr (M. Saoud).
www.elsevier.com/locate/b&c
Brain and Cognition 64 (2007) 257–264
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visual-perceptual functions such as simple visual discrimi-
nation, spatial relationships, figure-ground processing (the
ability to distinguish an object from its back-ground),
visual working memory, and visual closure (the ability to
identify a figure when only fragments of it are presented).
The MVPT-V can be used as a diagnostic tool providing
a cut-off score for impairment, as well as providing sepa-
rate component scores that can be used to determine which
aspect(s) of visual perception is(are) impaired. A previous
study used a manual line bisection to compared perfor-
mances of schizophrenia patients, neglect patients, and
healthy controls (Michel et al., 2007). The authors showed
a significant leftward bias in sch izophrenia patients, which
as in neglect patients could result from a lateralized anom-
aly at the attentional level. Moreover, an ulterior study
showed that, as it is observed in neglect patients, a lateral-
ized anomaly could also exist at the representational level
in schizophrenia (Cavezian et al., 2007). Nevertheless, pos-
sible visual -perceptual implications in this right hemine-
glect in schizophrenia have not been previously assessed
with neurological tools also used in neglect patients.
Thus, in order to examine potential analogies between
lateralized a nomalies in schizophrenia and hemineglect,
several aspects of visual spatial processing were assessed.
First, lateralized anomalies were assessed using a manual
line bisection task, with an additional attentional manip-
ulation (i.e., a local cueing paradigm). Second, to evalu-
ate whether or not lateralized anomalies do not result
from an impairment in basic visual-perceptual process-
ing, the visual-perceptual abilities of schizophrenia
patients were investigated using a clinical tool developed
for assessing hemineglect in stroke patients (i.e., the
Motor-free Visual Perceptual Test—vertical format:
MVPT-V). Performances of schizophrenia patients were
compared to those of healthy controls in order to exam-
ine visual-percep tual processing(s) impaired in schizo-
phrenia. To determine whether or not any observed
impairment also exists in other psychiatric patients, a
control group of depressed patients was added. Because
previous data reported numerous visual-perceptual
anomalies in schizophrenia patients (despite normal sen-
sory processing abilities, i.e., normal visual acuity), and
fewer visual-perceptual anomal ies in depressed patients
(for a review, Christensen, Griffiths, Mackinnon, &
Jacomb, 1997), we predicted that the performances of
schizophrenia patients would be worse than that of
depressed patients and healthy controls.
2. Methods
2.1. Subjects
Ten patients with schizophrenia (3 females; means ± SD
age = 36.0 ± 8.16) performed the MVPT-V and were com-
pared directly to the performance of 10 healthy controls (5
females; means ± SD age = 37.0 ± 8.65), and 10 depressed
patients (6 females; means ± SD age = 38.6 ± 14.72).
Patients were diagnosed according to DSM IV criteria
(American Psychiatric Association, 1994). All received
medication (antipsychotic medication such as haloperidol,
flupentixol, cyamemazine, loxapine, olanzapine, or antide-
pressant medication such as mirtazapine, paroxetine, vilox-
azine, fluoxetine, amitryptiline, venlafaxine, or
clomipramine) at the time of testing, and were stable, clin-
ically and in their medication, for at least one month prior
to testing. Clinical symptoms of both groups of patients
were assessed using the Brief Psychiatric Rating Scale
(Overall & Gorham, 1962). Moreover schizophrenic symp-
toms were assessed using the Scale of Asse ssment of Posi-
tive Symptoms (SAPS; Andreasen, 1984) and the Scale of
Assessment of Negative Symptoms (SANS; Andreasen,
1983). Exclusion criteria for all participants included any
non-corrected visual problems, any hist ory of neurological
symptoms, or psychiatric symptoms other than schizophre-
nia or de pression, respectively, for patient groups. All par-
ticipants (except one male left handed schizophrenia
patient) were right handed as assessed with the Edinburgh
inventory (Oldfield, 1971). This study was approved by the
local Ethics Committee and written informed consents
were obtained. The three groups were not significantly dif-
ferent in age (one-way ANOVA, p > .50, F(2, 27) = 0.14),
education level (ANOVA, p > .10, F(2,27) = 2.12), and
sex ratio (p > .20, v
2
= 1.90, df =2)(Table 1).
2.2. Experimental procedure
2.2.1. Manual line bisection task
Subjects were comfortably seated in front of a table and
were verbally informed of the procedure. They were asked
to perform the line bisection task. This task is one of sev-
eral traditional clinical tests commonly used to diagnose
and define visual neglect (e.g., Halligan & Marshall,
1988). It consists of a spatial judgment task that requires
subjects to indicate the centre of a horizontal line, as accu-
rately as possible using their dominant hand (right hand for
all but one participant), by making a mark across the cen-
tre of the line that would divide it exactly in two halves.
The pe n, arm and hand were positioned so as not to hide
any part of the line. Subjects were presented with 24 black
lines (200 mm long and 1 mm wide), which were presented
one by one horizontally and centrally on A4 sheets. A local
cueing paradigm was also included to assess the possible
influence of attention in any obs erved lateralized bias. That
is, of these 24 lines, subsets of 6 lines had either a number
at the left end, or at the right end, or at both ends (‘‘Double
cue’’ condition), or no number at either end (‘‘No cue’’
condition). The numbers used were 3, 4, 5, 6, 7, and 9,
and they were separated from the end of a line by a
6 mm space. Each number was 9 mm in height and 6 mm
wide. In the ‘‘Double cue’’ condition, numbers were differ-
ent but quite similar for optical density (i.e. 3/ 5; 6/9; 4/7).
This precaution was taken in order to avoid any spatial
perceptual bias. The position for the numbers was counter-
balanced in all the cueing conditions. Therefore, both in
258 C. Cave
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the ‘‘One cue’’ and ‘‘Double cue’’ conditions the numbers
were symmetri cally presented. Furthermore, cued and
uncued conditions were ordered pseudorandomly. The
lines were presented in front of the subject’s body midline
and the viewing distance was approximatel y 45 cm from
the line. There was no time limit.
2.2.2. Manual visual perceptual test—Vertical format
This is a 36-item, individually administered, multiple-
choice test (see Fig. 1 for examples). The test is divided into
five sections, each of them with specific instructions and
beginning with an example trial to ensure that the partici-
pant understood the instructions of each section (for a
Table 1
Clinical and demographic characteristics of healthy control group, schizophrenia group, and depressed group
Healthy control (n = 10) Depressed patients (n = 10) Schizophrenia patients (n = 10) p
Mean age (years ± SD) 37.00 ± 8.65 38.60 ± 14.72 36.00 ± 8.16 n.s.
a
Mean educational level (years ± SD) 12.60 ± 2.50 12.60 ± 3.63 10.40 ± 1.84 n.s.
a
Sex ratio
(Men/Women) 5/5 4/6 6/4 n.s.
b
BPRS total score 45.6 ± 8.55 49.7 ± 13.81 n.s.
c
SAPS total score 50.70 ± 28.53
SANS total score 65.00 ± 26.13
Duration of illness (months) 282.5 ± 746.0 69.9 ± 83.0 n.s.
c
Imipramine equivalent (mg/day) 144.44 ± 68.47
Chlorpromazine equivalent (mg/day) 482.40 ± 598.06
SD, standard deviation.
n.s., non-significant (p > 0.05).
a
One-way ANOVA.
b
v
2
comparison between the three groups.
c
Student t-test.
Fig. 1. Examples of two items of the MVPT-V (Mercier et al., 1997), with the gracious authorization from the Academic Therapy Publications, CA, USA.
Participants were required to indicate which of the four possible targets presented below the probe stimulus actually contained the probe figure (i.e. the
upper figure depicting a ‘Z’ in panel a, and a sail boat in panel b). In Panel a the probe is presented among other intact line drawings (correct answer is ‘a’).
In Panel b, the probe is presented along with distracting stimuli (random shapes and lines) such that the subject must be able to disambiguate the probe
from the distracting stimuli (in this case the correct answer is ‘b’).
C. Cave
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detailed description, see Eimon, Eimon, & Cermak, 1983).
Based on a previous study (Eimon et al., 1983), items of the
MVPT-V were divided into 6 exclusive categories, depend-
ing of the process assessed: (1) visual discrimination; (2)
spatial relationships; (3) figure-g round segregation; (4) spa-
tial relationship/figure-ground segregation; (5) visual mem-
ory; and (6) visual closure.
2.3. Data analysis
All statistics were performed with the STATISTICA
software package (release 5.5., 2000; StatSoft, Tulsa, OK,
USA). The a-level was set at .05. Values presented in the
results section are mean scores ± standard deviation.
2.3.1. The manual line bisection task
As previously described (Michel et al., 2007), the dis-
tance between the subject’s mark and the subjective mid-
point was carefully measured to 0.5 mm accuracy.
Rightward biases (i.e. rightward errors from the true centre
of the line) were given a positive value and leftward biases
(i.e. leftward errors from the true centre of the line) were
given negative values.
Mean biases for each subject in each cue condition were
analyzed using a two-way analysis of variance (ANOVA)
with the three groups (healthy participants, schizophrenia
patients, depressed patients) as the between-subjects factor
and the cue condition (no cue, two cues, right cue, left cue)
as the within-subjects factor. Contrast analyses were run to
assess the specific effect of each factor when appropriate.
Mean bias was also compared to zero, the theoretical value
of a perfect bisection, using one sample t-tests.
2.3.2. The MVPT-V
For each category (except the two first where the three
groups had same performances), and the overall number
of errors, one-way ANOVAs of the mean number of errors
of each group were performed. Contrast analyses were run
to assess the specific effect of each factor when appropriate.
2.3.3. Clinical correlations
For each task (the overall score in the MVPT-V, and
each cue condition in the manual line bisection), Pearson’s
product-moment correlations were used to assess the rela-
tionship between performances and the clinical profile of
each patients group (i.e., BPRS scores and duration of ill-
ness for both groups, SAPS and SANS scores and chlor-
promazine equival ent dosages in schizophrenia patients,
and imipramine equivalent dosages in depressed patients).
3. Results
3.1. The manual line bisection
The two-way ANOVA performed on the mean bias
showed a main effect of cue condition (F(3, 81) = 18.39;
p < .01) and no other significant effect. Although the group
effect only tended to be significant (F(2, 27) = 2.82; p < .08),
detailed contrast analyses took into account the group fac-
tor as the graphic representation (Fig. 2) suggested a simi-
lar pattern of performances in schizophrenia and depressed
patients which seeme d different from the pattern of perfor-
mances of healthy participants (in agreement with the trend
towards a significant group effect). This detailed analysis
(presented in Tabl e 2) can be resumed as follow:
- Healthy participants performances were influenced by
the presence of the cue; they bisected lines to the left
of the true centre in the ‘‘Left cue’’ (2.90 mm ± 3.49)
Healthy controls
3
Depressed patients
Schizophrenics
2
1
0
-1
-2
-3
-4
-5
Left cue No cue Double cue Right cue
Cue condition
Mean biais (mm)
Left Right
True centre
Fig. 2. Evolution of the mean bias (mm) observed in the manual line
bisection for each group in each cue condition (leftward biases are
indicated with a negative value, whereas rightward biases are given a
positive value). Whereas the traditional cueing effect was observed in
healthy controls (i.e., bisection mark deviated towards the cued extremity
of the line), depressed and schizophrenia patients responded only to the
presence of a right cue (in comparison to the no cue condition). Moreover,
only schizophrenia patients presented a significant leftward bias in the no
cue condition. Please, see text for detailed statistical analyses.
Table 2
Detailed analysis of the manual line bisection performances (significant
effects are indicated in italics)
Two-way analysis of variance
Main group effect F(3,81) = 18.39 p = .077
Main cue condition effect F(2, 27) = 2.82 p < .001
Contrast analysis in Healthy
participants
Depressed
patients
Schizophrenia
patients
F(1,27) pF(1,27) pF(1,27) p
No cue vs. Double cue 7.04 .013 1.50 .231 1.42 .243
No cue vs. Right cue 20.40 <.001 7.96 .009 11.88 .002
No cue vs. Left cue 5.15 .031 .17 .684 .04 .843
In healthy participants, performances in the no cue condition were sig-
nificantly different from those in all the other cue conditions. Moreover,
performances in the double cue condition were significantly different from
performances in the left cue condition but only tended to be significantly
different from performances in the right cue condition. However, the only
significant difference observed in depressed patients and schizophrenia
patients was between performances in the no cue condition and in the right
cue condition. An additional marginally significant difference was also
observed in schizophrenia patients between performances in the double
cue condition and performances in the right cue condition.
260 C. Cave
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and the ‘‘No cue’’ (1.52 mm ± 2.58) conditions,
whereas their bisection was accurate in the ‘‘Double
cue’’ condition (0.09 mm ± 2 .71), and to the right of
the true centre in the ‘‘Right cue’’ condition
(1.66 mm ± 2.79); nevertheless, left bias in the no cue
condition was not significantly different from zero the
theoretical value of a perfect bisect ion (t-test, p > .05).
- Depressed patients performances were influenced only
by the presence of a right cue; although they bisected
lines to the left of the true centre in all cue conditions
but the ‘‘Right cue’’ condition (Left cue:
1.45 mm ± 2.99; No cue: 1.70 mm ± 2.55; Double
cue: 0.96 mm ± 2.46; Right cue: 0.28 mm ± 2.92), they
showed no significant bias in the no cue condition (t-test,
p > .05).
- Schizophrenia patients performances were significantly
affected by the presence of a right cue; they bisected lines
significantly to the left of the true centre in all cue con-
ditions but the ‘‘Right cue’’ condition (Left cue:
3.53 mm ± 2.06; No cue: 3.65 mm ± 2.11; Double
cue: 2.93 mm ± 1.82; Right cue: 1.22 mm ± 2.64);
moreover their performance in the ‘‘No cue’’ condition
was significantly different from zero (t-test, p < .01).
In the end, overall performances of healthy participants
were not significantly different from those of depressed
patients (F(1, 27) = 0.08; p > .10), whereas they were signif-
icantly different from those of schizophrenia patients
(F(1, 27) = 4.78; p < .05). Nevertheless, performances of
schizophrenia patients only tended to be significantly dif-
ferent from those of dep ressed patients (F(1, 27) = 3.59;
p < .07).
In summary, although schizophrenia and depressed
patients tended to have a similar pattern of performances,
the former tended to have a larger leftwards bias in all con-
ditions than did the later.
3.2. The MVPT-V
One-way ANOVAs performed on each category of the
MVPT-V (except the two first categories), showed a signif-
icant group effect in the memory category (F(2, 27) = 4.66;
p < .05), in the visual closure category (F(2, 27) = 8.11;
p < .01), and in the overall score (F(2, 27) = 7.40; p < .01).
In all cases, contrast analyses showed that schizophrenia
patients made significantly more errors than healthy partic-
ipants (Memory category: F(1, 27) = 7.75, p < .01; Closure
category: F(1,27) = 13.78, p < .01; Overall score:
F(1,27) = 13.15, p < .01) and than depressed patients
(Memory category: F (1, 27) = 6.13, p < .05; Closure cate-
gory: F(1,27) = 10.28, p < .01; Overall score:
F(1,27) = 8.54, p < .01) whose performan ces were not sig-
nificantly different from the healthy controls (Memory cat-
egory: F(1,27) = 0.10, p > .50; Closure category:
F(1,27) = .26, p > .50; Overall score: F(1, 27) = .50,
p > .45) (Table 3).
3.3. Clinical correlations
In schizophrenia, no significant correlations were
observed between performances and clinical profile. How-
ever, in depressed patients, significant correlations were
observed between the imipramine equivalent dosage and
performances in the manual line bisection in the left cue
(r = .67, p < .05), the no cue (r = .67, p < .05), and the
double cue (r = .76, p < .05) conditions. These correla-
tions show that increasing antidepressant treatment may
induce a shift from a rightward bias to a leftward bias in
their performances in the manual line bisection task
(Fig. 3).
4. Discussion
In order to examine potential analogies between later-
alized anomalies in schizophrenia and hemineglect, the
visuo-spatial and visuo-perceptual abilities of 10 schizo-
phrenia patients were compared to those of 10 healthy
controls, and 10 depressed patients, using the manual line
bisection task and the MVPT-V. In the manual line bisec-
tion, in the ‘‘No cue’’ condition, only schizophrenia
patients showed a significant leftward bias in their estima-
tion of the centre of a line (and healthy controls and
depressed patients showed a non-significant leftward
bias). The classical cueing effect was observed in the con-
trol group (i.e., bisection mark deviated towards the cued-
end of the line), however, this was not found in depressed
or schizophrenia patients as they were only sensitive to a
right cue. Performances on the MVPT-V showed that schizo-
Table 3
Mean number of errors standard deviation) per group in the MVPT-V
Healthy controls (n = 10) Depressed patients (n = 10) Schizophrenia patients (n = 10) p
1. Visual discrimination 0 0 0
2. Spatial relationship 0.1 ± 0.32 0.1 ± 0.32 0.1 ± 0.32
3. Figure ground 0 0.2 ± 0.42 0.3 ± 0.48 n.s.
4. Spatial relationship/Figure ground 0 0.1 ± 0.32 0.2 ± 0.42 n.s.
5. Visual memory 0.3 ± 0.48 0.4 ± 0.7 1.2 ± 0.92 <.02
6. Visual closure 0.1 ± 0.32 0.4 ± 0.7 2.3 ± 2.16 <.01
Overall score 0.5 ± 0.85 1.2 ± 1.62 4.1 ± 3.38 <.02
n.s., one-way ANOVA, non-significant group effect (p > .05).
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phrenia patients performed worse than both control
groups, without being pathologic (in a neurological
meaning).
In healthy participants, a trend towards a leftward bias
in manual line bisection is a well-known phenomenon
referred to as pseudoneglect (for review, Jewell &
McCourt, 2000), and is assumed to represent a right hemi-
sphere dominance in that type of visuo-spatial task (e.g.,
Laeng, Buchtel, & Butter, 1996). Moreover, the effect of
the local cueing paradigm observed in our group of healt hy
participants is similar to what is classically described in the
literature; that is, bisection marks tend to be drawn
towards the location of the cue (e.g., Milner, Brechmann,
& Pagliarini, 19 92 ).
In schizophrenia patients, the significant leftward bias
observed in the no cue condition might be interpreted as
an attentional (e.g., Posner et al., 1988) or intentional/pre-
motor deficit toward the right hemispace (e.g., Downing,
Phillips, Bradshaw, Vaddadi, & Pantelis, 1998). This later-
alized impairment may reflect a right hemisphere over-acti-
vation or a left hemisphere under-activation (Cavezian,
Striemer, Saou d, Rossetti, & Danckert, 2006; Danckert,
Saoud, & Maruff, 2004; Downing et al., 1998) consistent
with a right he mineglect in schizophrenia patients (e.g.,
Posner et al., 1988). With respect to the local cueing para-
digm in schizophrenia patients, our results showe d that
they were influenced only by a cue placed at the right
extremity of the line. This result may appear to be some-
what inconsistent with a right hemineglect in these patients
(i.e., it could be interpreted as a failure to appropriately
attend to the left sided cue). Nevertheless, one could sug-
gest that schizophrenia patients did not demonstrate any
differential biases in the left cue and no cue conditions as
in both conditions their attention was already oriented
towards the left side of the line. In contrast, the right sided
cue re-oriented their attention tow ards the right ‘pseudo-
neglected’ side of the line thereby altering their bisection
performance. In other words, schizophrenia patients have
a ‘natural’ tendency to bias their attention towards the left
side, and thus neglect the right side, but are still able to re-
orient attention towards the right side if their atte ntion is
attracted by a strong enough cue (Michel et al., 2007). This
pattern of performance is consistent with a model of a right
hemisphere advantage (or a left hemisphere disadvantage)
to explain right hemispatial inattention in schizophrenia
(Cavezian et al., 2006; Danckert et al., 2004; Downing
et al., 1998; Posner et al., 1988). Follow ing this model, in
‘normal’ conditions a left hemisphere under-activation
associated with a right hemisphere over-activation would
result in a leftward bias in the no cue condition. However,
the presence of a cue at the right end of the line would
remove this imbalance (by inducing a stronger activation
in the left hemisphere) and thus result in an improvement
of schizophrenia patients performances. On the other
hand, a cue placed at the left extremity of the line would
be inefficient as the right hemisphere is already over-acti-
vated. In the end, the lack of correlations between perfor-
Left-cue condition
Y = 2.20 - 0.03 x
4
2
0
-2
-4
-6
-8
0 50 100 150 200 250
Imipramine equivalent dosage (mg/day)
No-cue condition
Y = 1.20 - 0.03 x
4
2
0
-2
-4
-6
-8
0 50 100 150 200 250
Imipramine equivalent dosage (mg/day)
Mean biais (mm)
Left Right
Mean biais (mm)
Left Right
Double-cue condition
Y = 2.38— 0.03 x
3
2
1
0
-1
-2
-3
-4
-5
0 50 100 150 200 250
Imipramine equivalent dosage (mg/day)
Mean biais (mm)
Left Right
a
b
c
Fig. 3. Pearson’s product-moment correlation between imipramine equivalent
dosage and performances in the manual line bisection (a: Left-cue condition; b:
No cue condition; c: Double cue condition) in depressed patients.
262 C. Cave
´
zian et al. / Brain and Cognition 64 (2007) 257–264
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Author's personal copy
mances in the manual line bisection and clinical profile of
our schizophrenia patients suggests that these lateralized
anomalies may not depend of these parameters. Although
this cannot completely exclude any effect of the antipsy-
chotic treatment, this lack of correlation is consistent with
previous studies showing that the main deleterious effect of
medication is a slowing in processing speed or motor
response, some improvements of attention or learning
behaviour being reported after pha rmacological treatment
(e.g., Stip, 200 6 ).
Concerning depressed patients, they were not signifi-
cantly differen t from healthy participants, and both groups
showed a trend towards a leftward bias (non-significantly
different from perfect bisection) in the no cue condition.
Nevertheless, the overall performance of depressed patients
tended to be significantly different from the schizophrenia
patients. Both data suggest that depressed patients had
intermediary performance between healthy participants
and schizophrenia patients. In general, previous reports
have suggested that patients with schizophrenia demon-
strate a greater degree of impairment on a wide range of
tasks than do patients with depression (e.g., Koelkebeck,
Ohrmann, Hetzel, Arolt, & Suslow, 2005; Schwartz, Evans,
Pena, & Winstead, 1994). Interestingly, depressed patients
seemed to respond to local cues in the line bisection task
in the same way as did schizophrenia patients. Indeed, both
groups responded to a cue placed at the right extremity of
the line but not to a cue placed at the left extremity (Fig. 2).
Consequently, it seems that lateralized anomalies in visuo-
spatial processing may also exist in depressed patients. On
the other hand, significant correlations with antidepressant
treatment show that the direction and the magnitude of the
bias is altered by the medication such as patients with low
level of antidepressant dosage showed thus a rightward
bias, whereas patients with high antidepressant dosage
showed a leftward bias in the manual line bisection task.
These correlations thus suggest that antidepressa nt medica-
tion could affect hemispheric asymmetry as assessed in a
manual line bisection. In the framework of hemispheric
asymmetry in depression and depressive mood, it has been
proposed that there is a right hemisphere hyperactivity
although it is associated to a right hemisphere functional
deficit (for review, Rotenberg, 2004). Indeed, the right
hemisphere over-a ctivity may concern only affect process-
ing, which in turn impaired right hemisphere functioning
in other cognitive processing. In the framework of antide-
pressant effect on hemispheric asymmetry, it has been
shown that at a behavioural level, treatment responder
present a heightened left hemisphere advantage, although
these studies a re scarce and co ncern almost only fluoxetine
treatment (e.g., Bruder, Stewart, McGrath, Deliyannides,
& Quitkin, 2004). In that context, we can assume that anti-
depressant treatment may increase activity in the left hemi-
sphere which then may compensate the right hemisphere
over-activity, and thus restore right hemisphere functioning
(at a behavioural level), although asymmetric antidepres-
sant effect is still not well understood. Following the
assumption, the shift from a rightward bias to a leftward
bias with increasing antidepressant dosage observed in
the present study results from a progressive improvement
of the right hemisphere functioning with the antidepressant
dosage. Nevertheless, as it is, to our knowledge, the first
study using a manual line bisection task in depressed
patients, more detailed studies using this tool are needed
to confirm these preliminary observations.
Performance on the MVPT-V showed that, whereas
healthy participants and depressed patients performed sim-
ilarly, schizophr enia patients performed more poorly than
both groups in the overall score. This difference is driven
mainly by poorer performance on the spatial working
memory and the visual closure categories in the schizophre-
nia patients. Globally, and in accordance with previous
research the current data show that: 1/schizophrenia and
depressed patients are not impaired in basic processes of
simple discrimination or recognition (Christensen et al.,
1997; Eimon et al., 1983); and 2/working memory deficits
are greater in schizophr enia than in depression (Egeland
et al., 2003 ). Taken together, these data su ggest that the
right hemineglect observed in schizophrenia is not due to
a sim ple visual-perceptual deficit (the same suggest has
been made regarding neglect patients for many years; see
Danckert & Ferber, 2006 for review). Moreover, schizo-
phrenia patients also showed a specific deficit in the visual
closure task. Studies using the visual closure task in schizo-
phrenia patients are scarce, with the exception of two stud-
ies by Doniger and colleagues2001,20012002. These
authors used a more sophisticated visual closure task than
ours and showed poorer recognition in schizophrenia
patients than in controls (Doniger, Silipo, Rabinowicz,
Snodgrass, & Javitt, 2001). They also indicated that this
pattern of performance was different from those in other
neuro-psychiatric disorders (i.e., Huntington’s disease, Alz-
heimer’s disease, or Parkinson’ s disease). Our study
extends their data showing that this defect was not
observed in all types of psychiatric populations and is
therefore likely to be specific to schizophrenia. Finally,
even if worse performances are observed in schizophr enia
patients, none of the groups presented large visual-percep-
tual deficit. Conse quently, as in the hemineglect syndrome
a simple visual-perceptual deficit could not explain lateral-
ized anomalies observed in the manual line bisection.
In conclusion, this study shows that lateralized anoma-
lies can be observed in a simple visuo-spatial task such as
the manual line bisection task in schizophrenia and
depressed patients. These anomalies, which are signifi-
cantly larger in schizophrenia than in depression, may
result from hyper attention towards the right hemifield as
a consequence of a right hemisphere over-activation, and/
or a left hemisphere under-activation. Fin ally, as in the
hemineglect syndrome, these lateralized anomalies can
not be explained by simple perceptual deficits. These data
complete literature about a mild right hemineglect in
schizophrenia showing that different analogies in visuo-
spatial processing in schizophrenia and in hemineglect are
C. Cave
´
zian et al. / Brain and Cognition 64 (2007) 257–264 263
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Author's personal copy
possible. Indeed, in both pathologies the lateralized anom-
aly observed in a manual line bisection may imply an atten -
tional deficit (Michel et al., 2007), or a representational
anomaly (Cavezian et al., 2007), but no sim ple visual-per-
ceptual anomaly. Those analogies may reflect a parietal
cortex dysfunction in schizophrenia as recently suggested
by a review of literature (Cavezian et al., 2006).
Acknowledgment
The authors would like to acknowledge the financial
assistance provided to them by the Conseil Scientifique
de la Recherche, from Centre Hospitalier le Vinatier.
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