Neuroscience Letters 480 (2010) 162–166
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Neuroscience Letters
journal homepage: www.elsevier.com/locate/neulet
An ERP study on the effect of self-relevant possessive pronoun
Aibao Zhou a,b,∗ , Zhan Shi a,b , Pengying Zhang b , Peiru Liu a,b , Wei Han c , Huifen Wu b ,
Qiong Li b , Quanshun Zuo b , Ruixue Xia b
a
Laboratory of Brain, Self and Society, Northwest Normal University, Lanzhou 730070, PR China
Department of Psychology, Northwest Normal University, Lanzhou 730070, PR China
c
Department of History, Northwest Normal University, Lanzhou 730070, PR China
b
a r t i c l e
i n f o
Article history:
Received 9 March 2010
Received in revised form 17 May 2010
Accepted 10 June 2010
Keywords:
Self-referential processing
Pre-reflective self
Reflective self
Self-specificity
Possessive pronoun
P300
Event-related potential (ERP)
a b s t r a c t
The present study examined the electrophysiological correlates of the psychological processing of possessive pronouns such as “wo de” (Chinese for “my”/“mine”) and “ta de” (Chinese for “his”) using a
three-stimulus oddball paradigm. Sixteen participants were visually presented the stimuli (possessive
pronouns, small circle and big circle). The results showed that, relative to non-self-relevant possessive
pronoun “ta de”, self-relevant possessive pronoun “wo de” elicited a significantly larger P300 amplitude
independently. The present study suggested that the self-relevant possessive pronoun was psychologically important to human beings.
© 2010 Elsevier Ireland Ltd. All rights reserved.
Self-referential processing is common to the distinct concepts
of self in the different domains and concerns stimuli that are
experienced as strongly related to one’s own person [27]. A
large body of studies demonstrated there is a processing bias
existing in the human brain toward self-relevant stimuli rather
than non-self-relevant stimuli. As for behavior studies, selfrelevant information receives preferential access to attentional
resources compared with other information [1,2,10]. In addition, a meta-analysis confirmed the self-reference effect (SRE) in
memory, with self-referent encoding strategies yielding superior
memory relative to both semantic and other-referent encoding
strategies [32]. Moreover, a growing number of electrophysiological studies showed enhanced ERP activities toward various
self-relevant stimuli, such as N250 for face [23,33] and objects
[24], P300 for name [3,9,25,28,29], face [23,26,33] and autobiographical information [11], N400 for trait adjectives [37], and
LSW (late slow wave) for objects [24], rather than non-selfrelevant stimuli. As mentioned above, self-relevant stimuli receive
preferential processing compared with non-self-relevant stimuli. However, it should be pointed out that these studies mainly
adopted tasks involving the representation of self-related contents,
∗ Corresponding author at: Laboratory of Brain, Self and Society, Department of
Psychology, Northwest Normal University, 967, Anning East Road, Lanzhou, Gansu
730070, PR China. Tel.: +86 931 7975 269; fax: +86 931 7975 269.
E-mail addresses: selfl[email protected], [email protected] (A. Zhou).
0304-3940/$ – see front matter © 2010 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.neulet.2010.06.033
such as name, face, objects, trait adjectives and autobiographical
information.
According to William James, “a man’s Self is the sum total of all
that he CAN call his, not only his body and his psychic powers, but
his clothes and his house, his wife and children, his ancestors and
friends, his reputation and works, his lands and horses, and yacht
and bank-account” [13]. It is known that the possessive pronouns,
“my” and “mine”, mean anything “of or belonging to the speaker
or writer/me” [12] (e.g., it’s my apple; the apple is mine). In previous studies, the effect of possessive pronouns on the encoding
of pronoun–noun associations (e.g., my garden) was investigated
using MEG and EEG. The results indicated that later stage processing was able to distinguish between information related to “mein”
(German for “my”) and to “sein” (German for “his”) [36], and that
“mein” and “sein” (self and non-self) pronoun–noun associations
could be distinguished in the temporal region [35]. However, up to
date, no studies have investigated the neural correlates underlying
psychological processing of the self-relevant possessive pronouns.
Therefore, the present study was aimed to address the brain mechanism of the processing of self-relevant possessive pronoun via ERP
measures with high temporal resolution.
We hypothesized that there would be an effect of selfrelevant possessive pronoun, i.e., a processing bias in the human
brain toward self-relevant possessive pronoun rather than nonself-relevant possessive pronoun. To test the hypothesis, a
three-stimulus oddball paradigm was employed to expose participants to self-relevant possessive pronoun “wo de” (Chinese for
A. Zhou et al. / Neuroscience Letters 480 (2010) 162–166
163
Table 1
Results of the 2 (condition: “wo de”, “ta de”) × 9 (electrode: F3, FZ, F4, C3, Cz, C4, P3, PZ and P4) ANOVAS for the amplitude and latency of P300.
Times (ms)
P300 (amplitude)
P300 (latency)
Condition
Condition × Electrode
Electrode
F
p
F
p
F
p
2
12.84
0.69
0.00
0.42
0.46
0.04
18.64
2.68
0.00
0.04
0.55
0.15
7.28
1.45
0.00
0.18
0.33
0.09
2
“my” or “mine”) and non-self-relevant pronoun “ta de” (Chinese for
“his”). Compared with the non-self-relevant possessive pronoun
“ta de”, the self-relevant possessive pronoun “wo de” would be
processed preferentially, which may lead to enhanced ERP activity.
Sixteen healthy students (9 males, 7 females; aged 19–25 years
old, mean age: 22.2 years old) were enrolled in this experiment.
All subjects were native Chinese speakers, right-handed, with normal or corrected-to-normal vision. All participants gave written
informed consent.
In the experiment, the big circle was served as standard stimulus, the small circle was served as target stimulus and two
categories of possessive pronouns (“wo de”, “ta de”) were served
as distractors. The big circle was presented 1024 times (80%), the
small circle was presented 128 times (10%), the possessive pronoun
“wo de” was presented 64 times (5%) and the possessive pronoun
“ta de” was presented 64 times (5%). The entire experiment was
divided into eight blocks, and the onset sequence of stimuli was
randomized for each subject. One block lasted 6 min on average.
Participants were seated in a quiet room at approximately 75 cm
from the screen centre. The visual angle of the stimuli is 3◦ × 2◦ . At
the beginning of each trail, a small white cross appeared for 300 ms
followed by a gray screen whose duration varied randomly from
800 to 1200 ms. Then one of the four stimulus categories was presented for 1000 ms. The task of the participants was to observe the
stimuli carefully and make behavioral response to the small circle.
Half subjects were instructed to press “1” key and the remaining
subjects to press “4” key if the circle is small. The stimulus picture was terminated by a key pressing, or was terminated when it
elapsed for 1000 ms. Moreover, no response was required for pronoun stimulus and big circle. After visual presentation of stimuli,
a gray screen was presented for 1000 ms. Trails were randomized
across conditions, and all four conditions were evenly distributed
into the eight blocks. Between blocks, several minutes of rest
were taken appropriately. The experiment started with 20 practice
trails.
The electroencephalogram (EEG) was continuously recorded
from scalp electrodes using the 256-channel HydroCel Geodesic
Sensor Net (Electrical Geodesics, Inc., Eugene, OR). The impedance
for all electrodes was kept below 50 k, and all recordings were
referenced to Cz. Signals were amplified with a 0.1–100 Hz elliptical bandpass filter and digitized at a 250 Hz sampling rate. EEG data
were segmented to epochs of 1000 ms after stimulus onset with a
200 ms pre-stimulus baseline. For each trail, channels were marked
2
as artifacts if the signal variation exceeded 200 ␮V. Trials with more
than 10 channels marked as artifacts were excluded. For trials with
less than 10 channels marked as artifacts, an algorithm that derived
values from neighboring channels via spherical spline interpolation was used to replace bad channels. Trails were excluded if the
signal variation of HEOG and VEOG exceeded 140 ␮V and 55 ␮V,
respectively. EEG data were re-referenced off-line against the average reference. Epochs of EEG data in the same condition were
averaged to derive the ERP data. Prior to analysis, ERP data were
corrected to the 200 ms pre-stimulus baseline and digitally filtered
with 0.1 Hz high-pass and 30 Hz low-pass filter. Only ERPs elicited
by two categories of pronouns were analyzed. According to the
scalp distributions of each ERP component, the mean amplitude
and latency of P200 (103–251 ms) were measured and submitted
to 2 (condition: “wo de”, “ta de”) × 7 (electrode: Fp1, Fp2, F7, F8,
F3, Fz and F4) two-way repeated measures ANOVAs; the mean
amplitude and latency of P300 (299–503 ms) were measured and
submitted to 2 (condition: “wo de”, “ta de”) × 9 (electrode: F3, Fz,
F4, C3, Cz, C4, P3, Pz and P4) two-way repeated measures ANOVAs.
The electrodes were selected according to the international 10–20
system. The Greenhouse–Geisser correction was applied wherever
necessary.
As for P200 amplitudes, no main effects of condition and of
electrode emerged [F(1, 15) = 1.28, p = 0.276 and F(6, 90) = 1.79,
p = 0.181]. There was no interaction effect observed between condition and electrode [F(6, 90) = 0.51, p = 0.686]. Another ANOVA was
conducted on P200 latencies. No main effects of condition and
of electrode emerged [F(1, 15) = 0.78, p = 0.392 and F(6, 90) = 1.35,
p = 0.264]. No significant interaction between condition and electrode was observed for P200 latencies [F(6, 90) = 1.79, p = 0.171].
As for P300 amplitudes (Tables 1 and 2 and Figs. 1 and 2),
main effects of condition and of electrode emerged [F(1, 15) = 12.84,
p = 0.003 and F(8, 120) = 18.64, p = 0.000]. The condition × electrode
interaction was significant [F(8, 120) = 7.28, p = 0.001]. Simple
effects ANOVAs revealed that there were significant differences
between the “wo de” condition and the “ta de” condition at
C3 [F(1, 15) = 7.11, p = 0.018], Cz [F(1, 15) = 10.72, p = 0.005], C4
[F(1, 15) = 3.88, p = 0.068] (critical significance), P3 [F(1, 15) = 6.42,
p = 0.023], Pz [F(1, 15) = 57.55, p = 0.000] and P4 [F(1, 15) = 16.60,
p = 0.001].
Another ANOVA was conducted on P300 latencies. No main
effects of condition and of electrode emerged [F(1, 15) = 0.69,
p = 0.418 and F(8, 120) = 2.68, p = 0.044]. No significant interaction
Table 2
P300 amplitudes and latencies.
Electrode
F3
Fz
F4
C3
Cz
C4
P3
Pz
P4
wo de
ta de
Amplitude
Latency
Amplitude
Latency
0.29 (1.48)
−1.16 (2.47)
0.78 (2.07)
2.90 (1.73)
2.12 (2.00)
3.13 (1.77)
3.51 (2.01)
4.85 (2.41)
4.28 (2.17)
388.00 (84.70)
413.00 (75.24)
386.50 (67.07)
366.00 (51.89)
373.75 (52.90)
379.75 (55.53)
374.25 (42.56)
387.75 (48.98)
387.25 (45.24)
0.59 (1.41)
−1.15 (2.13)
0.77 (1.83)
2.28 (1.54)
1.17 (1.83)
2.76 (1.89)
2.86 (1.87)
3.12 (2.04)
3.58 (2.11)
399.50 (79.62)
428.00 (70.96)
368.75 (44.62)
368.25 (55.26)
379.50 (52.50)
371.25 (43.06)
361.25 (28.72)
382.50 (40.55)
346.50 (26.85)
Note: Amplitude values are in microvolts (SD). Latencies are in milliseconds (SD).
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A. Zhou et al. / Neuroscience Letters 480 (2010) 162–166
Fig. 1. Grand average ERPs at F3, FZ, F4, C3, Cz, C4, P3, PZ and P4 for the possessive pronoun “wo de” and “ta de” conditions.
between condition and electrode was observed for P300 latencies
[F(8, 120) = 1.45, p = 0.182].
As for P300 amplitude, the self-relevant possessive pronoun “wo
de” evoked larger amplitude than the non-self-relevant possessive
pronoun “ta de” at the C3, Cz, C4, P3, Pz and P4 electrodes. It has been
widely demonstrated that a larger P300 is elicited by the stimuli
representing the low-probability category when two stimulus categories are presented with one category occurring less frequently
[4]. In addition, stimulus properties that heighten the amplitude of
the P300 are relevant to the subject’s task [7]. Moreover, stimulus
characterized by intrinsic psychological relevance can evoke larger
P300 amplitude [15,16]. In the present study, both the self-relevant
possessive pronoun “wo de” and the non-self-relevant possessive pronoun “ta de” were served as low-probability and non-task
targets. However, there was significant difference between P300
amplitudes under the possessive pronoun “wo de” and “ta de” conditions, which revealed that it was the self-relevance of possessive
pronoun “wo de” that produced the processing bias, because the
possessive pronoun “wo de” was not only a low-probability target
but also an intrinsic psychological relevant stimulus. The result was
in agreement with findings of previous behavior studies [1,2,10]
and electrophysiological studies [8,11,23,24,26,33,35,36]. The current study demonstrated that there existed an effect of self-relevant
possessive pronoun.
As we know, the amplitude of P300 is proportional to the
amount of attentional resources engaged in processing a given
stimulus [14]. In addition, the emotional value hypothesis of P300
[15] states that, compared with neutral stimuli, stimuli high in
emotional value, evoking larger P300 amplitudes [15,34], receive
preferential access to attentional resources. Consistent with the
hypothesis of P300, a previous study proposed that the larger
P300 response to self-relevant targets was most likely due to
its emotional significance [11]. Hence, a possible explanation for
the finding is that the self-relevant possessive pronoun “wo de”
receives more attentional resources because it is emotionally
salient and more important to participants relative to the non-selfrelevant possessive pronoun “ta de”.
In addition to the existence of the effect of self-relevant possessive pronoun, this effect was found at two midline electrodes
(Cz, Pz), two right electrodes (C4, P4), and two left electrodes (C3,
P3). The results revealed that there was no right-lateralization of
the effect of self-relevant possessive pronoun in the current study.
In terms of lateralization of P300, some previous studies reported
the right hemisphere, in particular, the right superior frontal and
inferior parietal cortex, plays a predominant role in self-relevant
information processing [6,17], while other studies reported it does
not [24,30,31]. This absence of right-lateralization might suggest
that self-relevance in object recognition is not as prominent as that
in face or name recognition [24]. Hence, we suggest that, similar
to self-relevance of objects, self-relevance of possessive pronoun is
not prominent either.
Moreover, there was no significant difference between the
latencies evoked by the self-relevant possessive pronoun “wo de”
and the non-self-relevant possessive pronoun “ta de”, though the
effect of the self-relevant possessive pronoun emerged at highorder stage of cortical responding in the present study. P300 latency
is particularly sensitive to the duration of stimulus categorization
[18,22]. Manipulations that make it more difficult to categorize a
stimulus along a specified dimension increase the P300 latency
[5]. Our findings suggest that the self-relevance of the possessive
pronoun “wo de” does not impact the duration of stimulus classification.
Self-related contents, such as name, face, objects, trait adjectives
and autobiographical information, were adopted in previous studies. As we know, any conscious act has not only an object but also
and necessarily a subject [20]. However, the abovementioned selfrelated contents only involved the self-as-object (reflective self),
thereby ignoring the self-as-subject (pre-reflective self) [19] and
lacking self-specificity [19,21] which distinguish self from nonself according to two criteria: exclusivity and noncontingency [21].
Moreover, Legrand suggested the subjective dimension of consciousness is anchored to the subject’s body, in particular to the
sense of bodily anchoring one’s first-person perspective [20], and
the subjective perspective is self-specific [21]. In contrast to self-
A. Zhou et al. / Neuroscience Letters 480 (2010) 162–166
165
Fig. 2. Topographic voltage maps of P300 to the oddball visual targets for the possessive pronoun “wo de” and “ta de” conditions are displayed for eight time-points between
99 and 799 ms with interval of 100 ms. Scale is shown at the bottom.
related contents, self-relevant possessive pronoun was adopted
in the present study, in which the effect was demonstrated. We
suggest that, on the one hand, the self-relevant possessive pronouns refer to any one of the self-related contents; on the other
hand, the possessive pronouns refer to the relationship between
self and self-related contents. How does the brain respond to selfrelevant possessive pronoun, or how do we understand the effect
of self-relevant possessive pronoun? Tentatively, it may be derived
from pre-reflective self, self-specificity, or a bridge between prereflective self and reflective self. Future research should explore
the neural mechanism underlying the processing of them.
In summary, an ERP study was performed to examine the processing bias in the human brain toward self-relevant possessive
pronoun. The results demonstrated that P300 amplitude was aug-
mented for the self-relevant possessive pronoun “wo de” relative
to the non-self-relevant possessive pronoun “ta de” in the left,
midline, and right central-parietal areas between 299 and 503 ms
after stimulus onset. The larger P300 amplitude was interpreted
to reflect a processing bias toward the self-relevant possessive
pronoun “wo de” compared with the non-self-relevant possessive
pronoun “ta de”. We suggest that the self-relevant possessive pronoun is psychologically important to humans.
Acknowledgments
We thank Ying Zhu at Peking University for his advice and comments. We also thank Heping Wu, Dawei Wei and Youhao Zhai for
polishing this English version. In addition, we are also grateful for
166
A. Zhou et al. / Neuroscience Letters 480 (2010) 162–166
the helpful comments and suggestions made by two anonymous
reviewers. All errors remain our own. This product was funded by
the Knowledge and Technology Innovation Project of NWNU, award
number NWNU-KJCXGC-SK0303-2.
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