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In the Face of Emotions: Event-Related Potentials in Supraliminal and Subliminal Facial Expression Recognition


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Is facial expression recognition marked by specific event-related potentials (ERPs) effects? Are conscious and unconscious elaborations of emotional facial stimuli qualitatively different processes? In Experiment 1, ERPs elicited by supraliminal stimuli were recorded when 21 participants viewed emotional facial expressions of four emotions and a neutral stimulus. Two ERP components (N2 and P3) were analyzed for their peak amplitude and latency measures. First, emotional face-specificity was observed for the negative deflection N2, whereas P3 was not affected by the content of the stimulus (emotional or neutral). A more posterior distribution of ERPs was found for N2. Moreover, a lateralization effect was revealed for negative (right lateralization) and positive (left lateralization) facial expressions. In Experiment 2 (20 participants), 1-ms subliminal stimulation was carried out. Unaware information processing was revealed to be quite similar to aware information processing for peak amplitude but not for latency. In fact, unconscious stimulation produced a more delayed peak variation than conscious stimulation.
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Genetic, Social, and General Psychology Monographs
ISSN: 8756-7547 (Print) 1940-5286 (Online) Journal homepage:
In the Face of Emotions: Event-Related Potentials
in Supraliminal and Subliminal Facial Expression
Michela Balconi & Claudio Lucchiari
To cite this article: Michela Balconi & Claudio Lucchiari (2005) In the Face of Emotions: Event-
Related Potentials in Supraliminal and Subliminal Facial Expression Recognition, Genetic,
Social, and General Psychology Monographs, 131:1, 41-69, DOI: 10.3200/MONO.131.1.41-69
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Published online: 19 Aug 2010.
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In the Face of Emotions: Event-Related
Potentials in Supraliminal and Subliminal
Facial Expression Recognition
Department of Psychology
Catholic University of Milan
Department of Neurology
Neurological National Hospital “C. Besta”
ABSTRACT. Is facial expression recognition marked by specific event-related potentials
(ERPs) effects? Are conscious and unconscious elaborations of emotional facial stimuli
qualitatively different processes? In Experiment 1, ERPs elicited by supraliminal stimuli
were recorded when 21 participants viewed emotional facial expressions of four emotions
and a neutral stimulus. Two ERP components (N2 and P3) were analyzed for their peak
amplitude and latency measures. First, emotional face-specificity was observed for the
negative deflection N2, whereas P3 was not affected by the content of the stimulus (emo-
tional or neutral). A more posterior distribution of ERPs was found for N2. Moreover, a
lateralization effect was revealed for negative (right lateralization) and positive (left lat-
eralization) facial expressions. In Experiment 2 (20 participants), 1-ms subliminal stimu-
lation was carried out. Unaware information processing was revealed to be quite similar
to aware information processing for peak amplitude but not for latency. In fact, uncon-
scious stimulation produced a more delayed peak variation than conscious stimulation.
Key words: emotion; event-related potentials; facial expressions; subliminal stimulation
WHEN INDIVIDUALS SEE A FACE, they infer two main types of information.
The face is identified as a specific stimulus belonging to a unique individual, tak-
ing into account change in appearance, aging, and so forth. Second, facial ex-
pression is interpreted for its emotional content, which sets the modality for the
social interaction (Ekman, 1993). The dissociation between facial identity and
facial expression processing, as well as between facial expression and structural
Address correspondence to Michela Balconi, Department of Psychology, Catholic Uni-
versity, Milan, Italy; (e-mail).
Genetic, Social, and General Psychology Monographs, 2005, 131(1), 41–69
Copyright © 2006 Heldref Publications
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features of a facial stimulus, has been well documented by the cognitive model
of face recognition proposed by Bruce and Young (1986, 1998). This model sup-
poses that there are almost seven distinct types of information that can be derived
from the face, such as structure, expression, and identity information. These
types of information, which differ in terms of cognitive and functional sub-
processes, are called codes. An example of this functional distinction is derived
from the clinical field. Some prosopagnosic patients can still recognize and read
emotional clues from faces, despite their failure to recognize the face of close rel-
atives and even of themselves (Bentin, Deouell, & Soroker, 1999; de Gelder,
Frissen, Barton, & Hadjikhani, 2003; De Renzi, Perani, Carlesimo, Silveri, &
Fazio, 1994). Nevertheless, a main question is whether the cognitive processes
involved in distinct aspects of face processing may be topographically separated
in specific brain regions (Bentin & Deouell, 2000; Gur, Schroeder, Turner, Mc-
Grath, & Chan, 2002).
An increasing number of researchers have analyzed the cognitive and neu-
ropsychological features of face recognition (Posamentier & Abdi, 2003). To be
more specific, studies using positron-emission tomography (PET; Bernstein,
Beig, Siegenthaler, & Grady, 2002; Haxby, Hoffman, & Gobbini, 2000), func-
tional magnetic resonance imaging (fMRI; Adolphs, Tranel, & Damasio, 1998;
Grelotti, Gauthier, & Schultz, 2002; Kanwisher, McDermott, & Chun, 1997), and
event-related potentials (ERPs; Balconi & Lucchiari, 2005; Balconi & Pozzoli,
2003a; Eimer & McCarthy, 1999; Herrmann et al., 2002) have underlined the
brain specificity of emotion decoding.
ERP Measures and Face Recognition
In our current research, we considered previous approaches on emotional
face comprehension that used a neuropsychological paradigm of analysis and,
more specifically, ERP measures. Relevant evidence supporting the functional
specificity of brain mechanisms responsible for emotional face processing is of-
fered by psychophysiological studies using ERPs (Caldara et al., 2003; Eimer,
2000; Holmes, Vuilleumier, & Eimer, 2003). These studies have supported the
hypothesis that the process of facial expression recognition starts very early in
the brain (approximately 180 ms after stimulus onset), only slightly later than the
face selective activity reported between 120 and 170 ms (Bentin, Allison, Puce,
Perez, & McCarthy, 1996; Boetzel & Grusser, 1989; Linkenkaer Hansen et al.,
1998; Maurer, Le Grand, & Mondloch, 2002; Streit, Wölwer, Brinkmeyer, Ihl, &
Gaebel, 2000). Thus, the first perceptive stage, in which the individual completes
the “structural code” of face, is thought to be processed separately from and suc-
cessively to complex facial information such as emotional meaning (Bruce &
Young, 1998; Lane, Chua, & Dolan, 1998). Vanderploeg, Brown, and Marsh
(1987) reported that the visual presentation of emotional facial expressions elicit-
ed more negative amplitudes during 230–400 ms (N200 ERP effect) than did
42 Genetic, Social, and General Psychology Monographs
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neutrally rated stimuli. Similarly, Marinkovic and Halgren (1998) observed that
the presentation of emotional faces evoked a larger lateral occipito-temporal neg-
ativity during 200–400 ms than did a neutral face. Another study investigated the
influence of facial expressions and blurred faces on ERP measures, without any
differences between conditions at 120 and 170 ms after stimulus onset but with
significant differences in amplitude between 180 and 300 ms (Streit et al.). Sato,
Takanori, Sakiko, and Michikazu (2000) demonstrated that emotional faces (fear
and joy) elicited a larger negativity at approximately 270 ms than neutral faces
over the posterior temporal areas. Two theoretical positions were proposed to ex-
plain this early negative variation. The first interpretation supposed that N2 could
be a cognitive marker of the complexity and relevance of the facial stimulus (Car-
retié & Iglesias, 1995). Nevertheless, this position is in contrast with a large part
of the experimental evidence (see Marinkovic & Halgren; Sato et al.). A second
more plausible supposition is about the emotional specificity of N2. Indeed, not
only is it thought to be a marker of the emotional content of facial stimulus, it
may even signal different “semantic” or “functional value” of the emotional ex-
pressions (Balconi & Pozzoli, 2003b; Herrmann et al., 2002; Pizzagalli, Koenig,
Regard, & Lehmann, 1999).
A successive positive ERP deflection (the P300 effect) was monitored by
some authors after emotional stimulus presentation. Nevertheless, previous re-
sults on P3 are contradictory: In some cases, the neutral faces evoked lower am-
plitude than emotional ones (Herrmann et al., 2002; Keil et al., 2001; Keil et al.,
2002); other researchers found that the neutral stimuli evoked the highest peak
(Krolak-Salmon, Fischer, Vighetto, & Mauguière, 2001; Vanderploeg et al.,
1987). On one hand, the P3 effect should be related more generally to the emo-
tional meaning of a stimulus, even if not exclusive for faces, because it was ob-
served in response to adjectives or objects with an emotional content (Bernat,
Bunce, & Shevrin, 2001; Keil et al., 2001). On the other hand, it has been relat-
ed theoretically to motivated attention, and specifically this effect is viewed as re-
flecting decision or cognitive closure of the recognition process (Brázdil, Rektor,
Daniel, Dufek, & Jurák, 2001; Iragui, Kutas, Mitchiner, & Hillyard, 1993; Lang,
Bradley, & Cuthbert, 1997).
A Universe of Emotions?
The second main question of the current research is about the effect of
type of emotions on ERP correlates. In fact, most studies analyzed face-spe-
cific brain potentials but did not explore exhaustively the emotional content of
faces and its effect on ERPs (Eimer, 2000; Eimer & McCarthy, 1999). In some
cases, only a limited number of emotions were considered, usually comparing
positive and negative “basic” emotions, such as sadness and joy. Moreover,
Herrmann and colleagues (2002) investigated the specific effect of different
facial expressions by comparing expressions with three different emotional va-
Balconi & Lucchiari 43
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lences (sad, happy, and neutral). It appeared that structural information is
processed separately from emotional information, but no significant evidence
pointed out the influence of type of emotions on ERP measures. Nevertheless,
previous studies on impairments of facial expression recognition suggested
category-specific deficits for the decoding process of emotional expressions
(i.e., fear and not joy) after brain injury of the amygdala (Adolphs et al., 1998;
Davidson, 2001; Scott et al., 1997; Young, Hellawell, Van de Wal, & Johnson,
1996). Moreover, emotionally expressive faces have been shown to have an in-
fluence on a number of processes. Depending on the emotions, faces elicit dif-
ferential effects on sympathetic dermal and cardiovascular reactions (Lang,
Greenwald, Bradley, & Hamm, 1993), facial EMG (Dimberg, 1997), skin re-
action (Esteves, Parra, Dimberg, & Öhman, 1994), amygdalar activation in
functional-imaging studies (Morrison, Öhman, & Dolan, 1998), as well as
ERPs (Junghöfer, Bradley, Elbert, & Lang, 2001; Morita, Morita, Masashi,
Waseda, & Maeda, 2001). Viewing affective stimuli elicits emotional reactions
in self-report, autonomic, and somatic measures (Bradley, Lang, & Cuthbert,
In addition, previous research has found a modulation of late deflections of
ERP as a function of motivational significance (Lang et al., 1997). To be more
specific, greater magnitude of ERP deflection characterizes the response to emo-
tionally salient stimuli (unpleasant compared with neutral; Palomba, Angrilli, &
Mini, 1997; Schupp et al., 2000). This effect has been theoretically related to mo-
tivated attention, in which motivationally relevant stimuli naturally arouse and
direct attentional resource (Hamm, Schupp, & Weike, 2003; Keil et al., 2002;
Lang et al.).
Threatening Power and Relevance of Faces
How can we explain these effects of motivation and relevance of emo-
tional facial expressions on ERPs? As suggested by the “functional model,”
each emotional expression represents an individual’s response to a particular
kind of significant event—a particular kind of harm or benefit—that motives
coping activity (Frjida, 1994; Hamm et al., 2003; Moffat & Frijda, 2000). The
appraisal of motivational relevance is essential because it determines to what
extent a stimulus or situation furthers or endangers an organism’s survival and
adaptation to a given environment (Ellsworth & Scherer, 2003). The implica-
tions of the event for the well-being of the organism take a main stage, in-
volving primary appraisal, according to Lazarus (1999). This dimension occu-
pies a central position in appraisal theories. Smith and Ellsworth (1985) used
“importance” and “perceived obstacle,” and Scherer (2001) proposed “concern
relevance.” Relevance as a continuous dimension from low to high may depend
on the number of goals or needs affected and their relative priority in the hier-
archy. For example, an event is relevant if it threatens one’s livelihood or even
44 Genetic, Social, and General Psychology Monographs
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one’s survival. Negative emotions, such as anger or fear, are expressions of a
situation perceived as threatening for an individual’s safeguard, and, for this
reason, they require an increased level of attention (Ellsworth & Scherer). On
the contrary, positive emotions, such as joy, express the low-threatening value
of an external situation. They induce the perception of the individual’s effec-
tiveness in managing an external stimulus, and they do not require an increas-
ing of attentional effort. In this perspective, facial expressions are important in
explaining the emotional situation and can produce different reactions in a
viewer. The “significance” of emotional expressions for the viewers, in terms
of low- or high-threatening power and relevance and, on the whole, “experi-
ential meaning” (Frijda, 1986; Schorr, 2001) should influence both the physi-
ological (i.e., skin conductance or arousal) and the cognitive level (mental
processes as cognitive involvement and attentional level), with interesting re-
flexes on ERP correlates (Balconi & Pozzoli, 2003a; Keil et al., 2002; Lang et
al., 1993; Wild, Erb, & Bartels, 2001).
Objectives and Hypotheses
Hypothesis 1: Taking into account the controversial results of previous re-
search, the cognitive nature of the negative N2 and the positive P3 ERP variations
must be clarified. Moreover, their specificity for emotional facial expression de-
coding needs to be analyzed. For this reason, we compared emotional facial ex-
pression recognition with a neutral stimulation (neutral facial expression).
Specifically, we hypothesized that higher peak amplitude of N2 and P3 would de-
tect the emotional content of faces compared with neutral stimuli.
Hypothesis 2: A second question concerns whether the “semantic value” of
facial expressions could have an effect on stimulus elaboration and whether it
could be revealed by ERPs. For this reason, the usefulness of the functional
model has been tested by ERP measures. In line with this perspective, we hy-
pothesized that, if the model is a valid way of explaining the subject’s response
to emotional facial stimuli, and if the two ERP variations are useful markers of
cognitive processes underlying emotion decoding, then significant differences
would be found between the categories of high- and low-relevant emotion and
high- and low-threatening power emotion.
Hypothesis 3: The emotional-specific ERP variations are expected to be af-
fected by the emotional content of facial expression. Specifically, as suggested
by the functional model, we supposed that individuals might be more emotional-
ly involved by a high-threatening negative emotion (i.e., anger) than by a low-
threatening positive emotion (i.e., joy), and that they might have a more intense
emotional reaction while viewing a negative high-involving (high relevant: fear)
than a negative low-involving (less relevant: sadness) emotion (Lang, Nelson, &
Collins, 1990; Wild et al., 2001), with a higher peak for stimuli that produce
more intense emotional reactions.
Balconi & Lucchiari 45
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Twenty-one students of psychology at the Catholic University of Milan took
part in the research after giving informed consent. They all were right-handed
with normal or corrected to normal visual acuity (11 men and 10 women; age
range 21–25 years; M = 23.12, SD = 0.38), and all denied any history of neuro-
logical or mental abnormalities. They were recruited for a cognitive task of stim-
ulus elaboration and were not aware that the investigation of emotional variables
was the purpose of the experiment.
Stimulus Material
We took stimulus material from Ekman and Friesen’s (1976) set of pictures,
which comprised black and white photographs (11 ×15 cm) of male and female
actors, presenting happy, sad, hungry, fearful, or neutral faces. The photos were
identical in terms of lighting and angle. Each emotional expression was repre-
sented 10 times, resulting in a total of 50 stimuli.
Stimulus Evaluation
We asked all participants to analyze the actors’ facial expressions in the
photographs and to express the degree of their emotional involvement with
each emotion. To rate the emotional reaction to a single expression, we asked
participants to identify each expression and to quantify the strength of experi-
enced emotions. They correctly recognized the emotional value of the stimuli
(correct identification = 94.52 %). Moreover, they evaluated the two negative
high-threatening emotions more emotionally involving based on a 1-5-point
Likert-type scale (anger, M= 4.06, SD = .21; fear, M= 3.89, SD = .29) than
joy (M= 3.37, SD = .47), sadness (M= 2.60, SD = .32), and neutral (M= 1.25,
SD = .40). The statistical significance of the difference between the five facial
expressions was tested by an univariate analysis of variance (ANOVA): For the
main factor of emotion, F(4, 20) = 10.23, p = .001, η2= .49. A post hoc com-
parison (Dunnet test) showed different responses between high-threatening
negative emotions and joy matched with fear, F(1, 20) = 8.12, p = .001, η2=
.42, and anger, F(1, 20) = 9.05, p = .001, η2= .44; and sadness matched with
fear, F(1, 20) = 5.42, p = .001, η2= .36, and anger, F(1, 20) = 6.51, p = .001,
η2= .40. Anger and fear did not differ from each other. All four expressions
differentiated with the neutral expression: fear, F(1, 20) = 16.52, p = .001, η2
= .48; anger, F(1, 20) = 9.13, p = .001, η2= .43; and joy, F(1, 20) = 10.73,
p =.001, η2= .45.
46 Genetic, Social, and General Psychology Monographs
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We presented the photographs in a random order in the center of a computer
monitor placed approximately 80 cm from the participant, with a visual horizontal
angle of 4° and a vertical angle of 6° (STIM 4.2 apparatus). An interstimulus fixa-
tion point was projected at the center of the screen (a white point on a black back-
ground). In this experiment, participants were aware of the stimulus, which was pre-
sented for 500 ms on the monitor with an interstimulus interval (ISI) of 1,500 ms.
After a brief introduction to the laboratory, the participants were seated in a sound-
attenuated, electrically shielded room; they were asked not to blink during the task.
Each participant was told to observe the stimuli carefully for a successive recogni-
tion task. This task was finalized to keep the attention level high during decoding
of faces. An explicit response to some features of the stimulus was not required.
This was done (a) to avoid confounding motor potentials in addition to brain po-
tentials and (b) to not cause participants to be more attentive to the emotional stim-
uli than the neutral ones. Prior to recording ERPs, each participant was familiarized
with the overall procedure (training session), during which he or she saw all the
emotional stimuli presented in a random order in the successive experimental ses-
sion (a block of 10 trials; each expression repeated twice).
Registration and ERP Measures
The electroencephalogram (EEG) was recorded with a 32-channel DC am-
plifier (SYNAMPS system) and acquisition software (NEUROSCAN 4.0, of
Neuroscan Labs, Sterling, VA) at 12 electrodes (4 central, Fz, Cz, Pz, Oz; 8 lat-
eral, F2, F3, T2, T3, P2, P3, O1, O2; International 10-20 system; Jasper, 1958)
with reference electrodes at the mastoids, and mounted in a Lycra electrode cap
(high-density registration). Electroculograms (EOGs) were recorded from elec-
trodes lateral and superior to the left eye. The signal (sampled at 256 Hz) was
amplified and processed with a pass-band from .01 to 50 Hz and was recorded in
continuous mode. Impedance was controlled and maintained below 5 K. An av-
eraged waveform (off-line) was obtained from approximately 10 artifact-free (tri-
als exceeding 50 V in amplitude were excluded from the averaging process) in-
dividual target stimuli for each type of emotion. The EEG signals were visually
scored on a high-resolution computer monitor, and portions of the data that con-
tained eye movements, muscle movements, or other artifacts were removed. Peak
amplitude measurement was quantified relative to 100 ms prestimulus. The noise
in the signal was low (5% epochs were rejected).
Component windows were defined for supraliminal conditions based on
grand average ERP wave forms across all types of emotion and electrodes. Be-
Balconi & Lucchiari 47
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cause both conditions N2 and P3 were apparent and morphologically similar, to
evaluate differences in ERP response, we focused data analysis within two time
windows, 180–300 ms and 300–380 ms. Two dependent variables, the peak value
(calculated from baseline to peak amplitude) and the latency of the peak, were
entered into a three-way repeated measures ANOVA, using the following: Type
of emotion (5) ×Localization (3) ×Lateralization (2). To assess lateralization, a
lateral electrode measure (F2, T2, P2, O2 vs. F3, T3, P3, O3) was created. The
localization effect (anterior, central, or posterior) was analyzed by means of three
separate electrodes (Fz vs. Cz vs. Pz). Type I errors associated with inhomo-
geneity of variance were controlled by decreasing the degrees of freedom using
the Greenhouse–Geiser epsilon.
Supraliminal Condition (N2 Effect)
The repeated measures ANOVA applied to peak value showed a significant
main effect for type, F(4, 20) = 21.22, p = .001, η2= .56, localization, F(2, 20)
= 11.07, p = .001, η2= .49, but not for lateralization, F(1, 20) = 1.42, p = .15,
η2= .18. The two three-way interactions were not statistically significant, except
for the two-way interaction Type ×Lateralization, F(4, 20) = 10.62, p = .001, η2
= .40. As shown in Figure 1A–C, a peak at approximately 230 ms (227 ms) is ob-
servable for the emotional expressions.
To compare one facial expression with another, we applied a successive post
hoc analysis (Dunnet test) to the type effect. Whereas anger and fear did not differ
from each other, joy, sadness, and neutral expressions had a more positive peak than
fear: For the match fear/joy, F(1, 20) = 9.11, p = .001, η2= .48; fear/sadness, F(1,
20) = 7.56, p = .001, η2= .41; fear/neutral, F(1, 20) = 11.06, p = .001, η2= .49;
and anger: anger/joy, F(1, 20) = 10.33, p = .001, η2= .50; anger/sadness, F(1, 20)
= 8.71, p = .001, η2= .44; anger/neutral, F(1, 20) = 11.21, p = .001, η2= .53.
Second, the post hoc analysis applied to the simple effect of localization re-
vealed that the negative deflection was higher in the posterior (Pz) than in the an-
terior (Fz), F(1, 20) = 8.77, p = .001, η2= .42, and the central (Cz), F(1, 20) =
5.02, p = .001, η2= .37, sites. Table 1 reports the mean values of peak variations
as a function of emotion and electrode site.
Finally, the post hoc comparison applied to the significant interaction Type
×Lateralization effect revealed a more right distribution for the negative expres-
sions of anger, F(1, 20) = 8.91, p = .001, η2= .38, fear, F(1, 20) = 15.39, p =
.001, η2= .46 and sadness, F(1, 20) = 6.04, p = .001, η2= .32, compared with
joy. The same trend was revealed for the negative emotions compared with the
neutral face for anger, F(1, 20) = 8.99, p = .001, η2= .39; fear, F(1, 20) = 11.61,
p = .001, η2= .51; and sadness, F(1, 20) = 6.12, p = .001, η2= .32. Figure 2 pre-
sents the topography of ERP as a function of type of emotion.
We applied a second repeated measures ANOVA to the latency dependent mea-
sure. No main effect was significant to the analysis: type, F(4, 20) = 0.64, p = .41,
48 Genetic, Social, and General Psychology Monographs
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Balconi & Lucchiari 49
Anger Sadness Joy NeutralFear
FIGURE 1. Grand-averaged waveforms at (A) Fz electrode site for five facial
expressions (supraliminal condition), (B) Cz electrode site for five facial ex-
pressions, (C) Pz electrode site for five facial expressions.
Amplitude (V)
100 200 300 400 500
AN2 P3
100 200 300 400 500
100 200 300 400 500
CN2 P3
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η2= .08, localization, F(2, 20) = 1.52, p = .27, η2= .11, and lateralization,
F(1, 20) = 1.05, p = .22, η2= .14, as well as their two three-way interactions. There-
fore, the peak latency was quite similar in each emotion and in all sites of the scalp.
Supraliminal Condition (P3 Effect)
The ANOVA (Type ×Localization ×Lateralization) applied to the peak
value showed the significance of only some main effects. In fact, whereas type,
50 Genetic, Social, and General Psychology Monographs
neutral joy sadness
anger fear
227 ms
FIGURE 2. Topographic maps at 230 mean square (ms) for five facial expres-
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F(4, 20) = 1.37, p = .38, η2= .09, and localization, F(2,20) = 1.22, p = .41, η2=
.08, were not significant, lateralization showed significant differences between
the right and left sides, F(1, 20) = 10.38, p = .001, η2= .45, with a more left-dis-
tributed peak. No other interaction effect was significant. Therefore, the P3 ERP
variation was undifferentiated between the five emotional expressions and the an-
terior/posterior localization.
The second ANOVA applied to the latency dependent variable did not find
significant effects for type, F(4, 20) = 1.75, p = .25, η2= .15, localization, F(2,
20) = 1.07, p = .59, η2= .12, and lateralization, F(1, 20) = 0.88, p = .62, η2=
.07, nor for their possible interactions. Therefore, the temporal appearance of the
peak variation was not differentiated between emotional/neutral stimuli, and a
similar peak profile was observed for the five facial expressions.
No other study has exhaustively analyzed the N2 variation to comprehend
its functional significance in emotional face recognition. Our data support the
view that emotion discrimination occurs at a first stage of conceptual stimulus
processing. Second, emotional facial expressions induce greater activation of
the posterior areas, with a latency of about 230 ms from stimulus onset. More-
over, N2 deflection is strictly related to the emotional value of faces (Streit et
al., 2000). A main point is that the negative deflection was not the result of a
global processing of facial stimuli, but it was more specifically related to emo-
tional expression decoding. Because emotional expression was differentiated
from neutral expression by ERPs, it could represent an explicit marker of emo-
tional facial expression and not a generic cue of facial stimulus comprehen-
sion. Moreover, differences in scalp localization of N2 were found. The nega-
tive variation was heterogeneously distributed on the scalp, and a posterior lo-
calization was observed. In previous studies, neural networks have been
demonstrated for processing specific facial emotions, with the implicated re-
gions including cortical (mainly prefrontal and occipito-temporal junction)
and subcortical structures (amygdala, basal ganglia, and insula; Damasio et al.,
2000; Gorno-Tempini, Pradelli, Serafini, Baraldi, & Porro, 2001). In line with
previous results, the posterior sites were observed as much more involved in
emotional facial expressions decoding than neutral stimuli (Sato et al., 2000).
On the contrary, based on the absence of P3 ERP differences between neutral
and emotional stimulation, we can suppose a different cognitive significance
of this positive ERP deflection. Previous data would suggest that the P3 is due
to processing facial stimuli (probably related to the complexity of the stimu-
lus) and that it might represent a general function of updating the memory
(Posamentier & Abdi, 2003), whereas N2 is more specifically related to ex-
pression decoding. Nevertheless, to comprehend more exhaustively the effec-
tive significance of this ERP effect, future exploration on the cognitive value
Balconi & Lucchiari 51
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of P3 with respect to emotion and face (e.g., through the comparison of emo-
tional face with other generic emotional stimuli) should be realized.
The second main result of this research is that N2 differs among the five emo-
tions in terms of peak amplitude, in contrast to what we found for P3. On the one
hand, differences in N2 profiles as a function of the emotional valence of the stim-
ulus may indicate the sensitivity of the negative-wave variation to the “semantic”
value of facial expressions (Jung et al., 2000). Very similar potentials, with identi-
cal early latency and amplitude, were observed for happy and sad expressions, dif-
ferentiated from the negative high-threatening and high-relevant emotions (fear and
anger). A more negative peak characterized, respectively, fear and anger than joy,
sadness, and neutral stimuli. These data appear to be partially in contrast with some
previous results (Sato et al., 2000). In fact, Jung et al. (2000) did not find significant
differences in a N270 peak between the two emotional expressions of fear and joy.
Nevertheless, some issues linked to that research must be considered. First, the
strict comparability of the two peaks (N230 and N270) and whether they represent
exactly the same cognitive response to the emotional stimuli should be discussed
(Rugg & Coles, 1995). Second, if it is so, an interesting correlation should be point-
ed out between type of emotion and peak intensity. In fact, a scalar higher negativ-
ity of the peak is noticeable, going from joy to fear, specifically for posterior sites
(T5 and T6), which suggests the hypothesis of an ascending trend of peak negativ-
ity as a function of increased arousal.
Our results allowed us to extend the range of emotions and to explore in de-
tail the functional value of facial expressions. Two main parameters seem to af-
fect the ERP profile: the high- and low-threatening significance and the relevance
of the emotional expressions. Specifically, it is assumed that not only negative
emotions (e.g., anger) may induce a stronger reaction by the individual than pos-
itive emotions (e.g., joy), with more intense emotional response, but that experi-
enced emotional intensity may increase while viewing a negative high-threaten-
ing emotion (e.g., fear) but decrease while viewing a negative low-threatening
emotion (e.g., sadness; Lang et al., 1990; Yee & Miller, 1987). This assumption
is strengthened by the finding of the corresponding behavioral responses of the
subjects: Fear and anger elicited negative intense feelings, whereas joy and es-
pecially sadness were less involving and intense. This would suggest that effects
due to emotional arousal should be greater for unpleasant relevant stimuli, which
were rated as slightly more arousing than less relevant stimuli. Therefore, it is as-
sumed that, as a function of relevance and threatening power (from higher to
lower), emotional expressions are distributed along a heterogeneous space, as
well as the individual’s emotional response to them, and this fact is reflected by
ERP variation with an increasing negativity of N230. Such evidence supports the
notion that affective processing happens on a broad continuum, as expected by
the functional model. In fact, from an evolutionary point of view, negative rele-
vant emotions appear to be most prominent as a human safeguard (Lang et al.).
Specifically, they facilitate the survival of the species and the immediate and ap-
52 Genetic, Social, and General Psychology Monographs
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propriate response to emotionally salient (threat-related) stimuli confers them an
“adaptive” value. For example, we can state that fear is related to feelings of high
attention, negative valence, high uncertainty about what is happening, or one’s
ability to cope with it. This appraisal produces specific physiological and cogni-
tive reactions, elicited by ERPs. On the whole, more negative and threatening fa-
cial stimuli may evoke greater arousal than positive, unthreatening stimuli, and
greater peak amplitude has been found to indicate these physiological and cog-
nitive responses (Polich & Kok, 1995).
Finally, an interesting main result of this research is a right lateralization ef-
fect observed for negative emotions compared with positive and neutral stimuli. A
considerable amount of research has investigated the lateralization of emotional
processing. According to the “right hemisphere hypothesis,” the right hemisphere
plays a superior role in emotional processing, such as recognition of both positive
and negative emotions (Borod et al., 1998). An alternative view, the “valence hy-
pothesis,” is that the right hemisphere primarily mediates negative rather than pos-
itive emotions (Davidson, 1993). In a recent review, Davidson, Jackson, and Kalin
(2000) suggested that right anterior brain regions are specialized for the produc-
tion and generation of certain negative rather than positive emotions, whereas
right posterior regions are involved in the perception of emotions, irrespective of
their valence. Our data seem to be better explained by the valence model of later-
alization because the “right hemisphere superiority” is not at all able to justify the
distinction between positive and negative cortical localizations revealed here.
From this perspective, future research should consider the lateralization effect
more exhaustively, using, for example, a more direct comparison between the
processes of production and recognition of facial expressions.
Emotion and Consciousness
The purpose of Experiment 2 was to elucidate the relationship between con-
scious and unconscious decoding of emotional facial expressions. Previous par-
adigms of analysis have focused on conscious elaboration of the emotional stim-
uli. In contrast with the amount of literature, in Experiment 2, we focused on the
effect of unconscious psychological mechanisms in emotion recognition. For ex-
ample, we asked how complicated the unconscious system is or whether it oper-
ates in a manner analogous to the conscious system. There is now considerable
evidence supporting the notion that significant affective processing happens out-
side conscious awareness (Bunce, Bernat, Wong, & Shevrin, 1999; Dimberg,
Elmehed, & Thunberg, 2000; LeDoux, 1996; Shevrin, Bond, Brakel, Hertel, &
Williams, 1996). In addition to consciously perceived stimuli, there are many
signals from without and within the individual that are perceived and processed
without any reportable awareness. The term implicit perception was suggested
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for this process (Kihlstrom, Barnhardt, & Tataryn, 1992), and an obvious exam-
ple, well-known from experimental psychology, is the phenomenon of sublimi-
nal perception. In addition, research on attention introduced a distinction be-
tween automatic and conscious (Posner, 1978) or automatic and controlled
(Shiffrin & Schneider, 1977) information processing. This concept was devel-
oped to account for the fact that the selectivity of attention is better described in
terms of a flexible and strategic distribution of limited processing resources
across stimuli and tasks.
Unconsciously mediated psychological phenomena could also be demon-
strated in clinical context. For example, prosopagnosia may result from dam-
age to visual association cortices. In some cases, it was demonstrated that
prosopagnosics appear to recognize familiar faces even though they fail to
identify the persons verbally (Tranel & Damasio, 1985). Thus, the patients
showed evidence of unconscious recognition that should not be accessed con-
sciously. From the viewpoint of neurophysiology, subliminal perception has
been studied only in a limited number of cases (Shevrin & Fritzler, 1968;
Wong, Shevrin & Williams, 1994). Some investigations were applied to the
classical oddball paradigm (Batty & Taylor, 2003; Bernat et al., 2001; Brázdil
et al., 2001) and found a P300 ERP effect (a positive deflection) for uncon-
scious stimuli similar to the supraliminal condition. This result might demon-
strate that ERPs can index unconscious mental processes (Shevrin, 2001).
ERPs have been shown to be sensitive to the conscious affective perception of
words (Cacioppo, Crites, & Gardner, 1996; Chapman, McCrary, Chapman, &
Martin, 1980; Skrandies & Weber, 1996), faces (Kayser et al., 1997), and pic-
tures (Johnston, Miller, & Burleson, 1986; Yee & Miller, 1987). However, al-
though the existence of unconscious effects was accepted, the question is still
open concerning their importance for emotional decoding. Kunst-Wilson and
Zajonc (1980) have demonstrated how unconscious affective stimuli can in-
fluence appraisal of conscious stimuli. Öhman (1999) reported conceptually
similar findings from experiments with human subjects conditioned to facial
stimuli paired with electric shock. When previously conditioned angry faces
were presented masked by neutral faces, which blocked their conscious recog-
nition, they nevertheless elicited conditioned responses. In addition, LeDoux
(1990) has argued that the core of the emotional system is a brain mechanism
that computes the affective significance of a stimulus; this brain mechanism is
part of what gives rise to the conscious experience of emotion, and it neces-
sarily operates outside of conscious awareness.
Subliminal and Supraliminal Stimulation Effects on ERP Correlates
Nevertheless, no previous study has explored the relationship between un-
conscious elaboration of emotional faces, type of emotions, and specific ERP ef-
fect. Could we suppose that the ERP profiles elicited by conscious and uncon-
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scious decoding are similar? Moreover, will the ERP differences observed in the
supraliminal condition between the emotions be reproduced in subliminal condi-
tion? We adopted a model of analysis that postulated homogeneous cognitive
processes for both subliminal and supraliminal stimulation (Shevrin, 2001).
Specifically, we hypothesized that (a) subliminal ERPs have a component struc-
ture similar to conventional supraliminal ERPs and (b) subliminal ERP compo-
nents have similar psychological properties to supraliminal ERPs.
Another main point of analysis is about the time of emergence of peak vari-
ation as a function of consciousness. In fact, as previously observed, delayed un-
aware information processing represents a distinctive feature of implicit visual
perception (Bernat et al., 2001; Junghöfer et al., 2001), and it was represented as
a consequence of a more complex cognitive process underlying unconscious
stimulation. Nevertheless, other authors have pointed out the presence of an an-
ticipated peak for subliminal stimuli compared with supraliminal ones (Brázdil
et al., 2001; Brázdil, Rektor, Dufek, Jurák, & Daniel, 1998). Finally, we analyzed
the lateralization effect due to the levels of consciousness. Specifically, Gazzani-
ga (1993) suggested that the left hemisphere is crucial for consciousness, and left
dominance in response to conscious stimuli is reflected in the left-brain decoder.
Nevertheless, some discrepancies were found from this theoretical perspective,
and an opposite right lateralization was revealed for conscious awareness
(Henke, Landis, & Markowitsch, 1993; Shevrin et al., 1996).
Objectives and Hypotheses
Hypothesis 1: In line with this model, we hypothesized that the wave pro-
files elicited by conscious and unconscious decoding might be similar with
respect to their peak values. Second, ERPs are sensitive to the affective va-
lence of a stimulus, whether processed in awareness or outside of con-
scious awareness. Therefore, we formulated some specific hypotheses
about supraliminal and subliminal stimulation.
Hypothesis 1a: The ERP differences related to the emotional content of fa-
cial expressions found for conscious decoding of faces as a function of high-
and low-threatening power and high and low relevance should be similar to
those produced by subliminal stimulation (Mogg & Bradley, 1999).
Hypothesis 1b: Differences between peak latencies of ERP are considered a
function of the conscious–unconscious elaboration. These differences will
be linked to underlying cognitive processes and, more specifically, to differ-
ent levels of attentional effort required to elaborate the stimuli.
Hypothesis 1c: Examinations of the effects of consciousness on hemispher-
ic asymmetries were planned. A lateralization effect of ERP correlates might
reveal the presence of different cortical sides for conscious and unconscious
information elaboration. In particular, left-side specialization for conscious
processing is predicted, as revealed by previous experimental results.
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Twenty students of psychology at the Catholic University of Milan took part
in the Experiment 2 (9 men and 11 women; age range 21–26 years; M = 23.64,
SD = 0.23).
The same facial stimuli (total of 50 stimuli) and experimental procedures of
Experiment 1 were used.
Subliminal Stimulation
In the subliminal condition, participants saw subthreshold stimuli. The
stimulus duration was 1 ms, with an ISI of 1,500 ms. Subliminal stimuli in the
current study met objective detection threshold criteria (Bernat et al., 2001).
Snodgrass (2000) argued that detection is sufficiently exhaustive to have a
conscious perception on the basis of signal detection theory. On the contrary,
according to signal detection theory, when detection sensitivity is at chance, it
is unlikely that there is conscious awareness of the stimulus (Macmillan, 1986;
Snodgrass, 2000).
Behavioral Measures (Stimulus Detection Test)
The effective inability to recognize the subthreshold stimuli previously viewed
by the participants was tested after the experimental session. In a target detection
task, we asked each participant to distinguish the stimuli previously viewed from a
set of new stimuli (for a total of 100 stimuli: 50 target, 50 nontarget). The presen-
tation sequence of target and nontarget stimuli was random. Detection did not dif-
fer from the chance mean of 50 (M = 47.13). All subliminal participants conformed
within an expectable chance distribution, t(19) = 0.76, p = .35 (one tailed).
ERP Measures
The same temporal windows of supraliminal condition were considered after
evaluating the morphological similarity of the two wave profiles. To allow for the
direct comparison of supraliminal and subliminal condition, we used a bivariate
correlation between the two-condition grand averages to describe numerically
this similarity in structure (R= .95, p= .001). Correlations between the individ-
ual electrodes were similarly positive and sizable (Fz, R= .65; Cz, R= .94; Pz,
R= .73; Oz, R= .54; F2, R= .48; F3, R= .51; T2, R= .70; T3, R= .64; P2, R=
.58; P3, R= .52; O1, R= .60; O2, R= .55; p= .001 for all). These correlations
56 Genetic, Social, and General Psychology Monographs
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indicate that positive and negative peaks in the ERPs to supraliminal and sub-
liminal stimuli tend to occur at the same latency and have the same form.
Subliminal Condition (N2 Effect)
We applied two repeated measures ANOVAs to the peak and latency depen-
dent variables (see Experiment 1). The first analysis (Type ×Localization ×Lat-
eralization) showed a significant main effect for type, F(4, 19) = 10.56, p = .001,
η2= .40, and localization, F(2, 19) = 15.63, p = .001, η2= .53, but not for later-
alization, F(1, 19) = 0.25, p = .61, η2= .04. Interaction effects were not signifi-
cant, except for Type ×Lateralization. Figure 3A–C shows the peak profiles of
N2 as a function of emotions. In terms of localization, as shown by post hoc
analysis, a more posterior (Pz) scalp distribution of the peak was observed com-
pared with frontal (Fz), F(1, 19) = 10.47, p = .001, η2= .43, and central (Cz),
F(1, 19) = 7.71, p = .001, η2= .30, sites.
Taking into account the type effect, post hoc analysis revealed ERP differ-
ences between anger and joy, F(1, 20) = 7.31, p = .001, η2= .38, sadness, F(1,
20) = 6.85, p = .001, η2= .37, and neutral, F(1, 20 = 18.20, p = .001, η2= .57,
faces. In parallel, fear differed from joy, F(1, 20) = 7.12, p = .001, η2= .39, sad-
ness, F(1, 20) = 6.21, p = .001, η2= .35, and neutral, F(1, 20) = 17.54, p = .001,
η2= .52, faces. Table 2 shows the mean value and standard deviation of N2 as a
function of type of emotion and sites.
The significant interaction effect Type ×Lateralization was successively an-
alyzed. As observed in the supraliminal condition (see Experiment 1), the Dun-
net test revealed a more right distribution for the three negative emotions. A high-
er peak at the right side was observed for the negative expressions of anger, F(1,
20) = 10.33, p = .001, η2= .48, fear, F(1, 20) = 14.62, p = .001, η2= .53, and
sadness, F(1, 20) = 6.89, p = .001, η2= .30, compared with joy. The same trend
was revealed comparing the negative emotions with neutral faces: for anger, F(1,
20) = 12.06, p = .001, η2= .50; fear, F(1, 20) = 13.45, p = .001, η2= .52; and
sadness, F(1, 20) = 9.04, p = .001, η2= .47.
The second ANOVA (latency as the dependent variable) showed a homoge-
neous temporal distribution of N2 for each emotion and on all of the sites be-
cause no main effect was significant: type, F(4, 20) = 1.01, p = .52, η2= .07; lo-
calization, F(2, 20) = 1.27, p = .42, η2= .10; and lateralization, F(1, 20) = 0.96,
p = .44, η2= .08.
Subliminal Condition (P3 Effect)
Two orders of data (peak and latency) were entered into two repeated
measures ANOVAs. The first analysis did not reveal significant main effects
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58 Genetic, Social, and General Psychology Monographs
Anger Sadness Joy NeutralFear
FIGURE 3. Grand-averaged waveforms at (A) Fz electrode site for five facial
expressions (subliminal condition), (B) Cz electrode site for five facial expres-
sions, (C) Pz electrode site for five facial expressions.
Amplitude (V)
100 200 300 400 500
AN2 P3
100 200 300 400 500
BN2 P3
100 200 300 400 500
CN2 P3
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or interactions for the independent factors. In fact, type, F(4, 20) = 1.42, p =
.39, η2= .08, localization, F(2, 20) = 1.11, p = .48, η2= .10, and lateralization,
F(1, 20) = 0.53, p = .51, η2= .05, did not show different mean values of the peak
measures. The latency measure had a similar trend to the peak data. In fact, not
only did type of emotion, F(4, 20) = 1.91, p = .13, η2= .12, not produce tempo-
ral variation of peak appearance, but there were no differences between the right
and left sides, F(1, 20) = 0.91, p = .48, η2= .07, and anterior and posterior dis-
tributions, F(2, 20) = 1.02, p = .44, η2= .10, in terms of latency.
Supraliminal and Subliminal Comparison
We entered supraliminal and subliminal conditions together in one statisti-
cal analysis to compare the two conditions directly. Two mixed-design ANOVAs,
with condition as the between-subject measure, and type, localization, and later-
alization as within-subject measures, were applied to peak and latency dependent
measures for each of the two ERP variations N2 and P3.
N2 effect. For the first negative deflection N2, the peak variable was differentiat-
ed as a function of the main effect of type, F(4, 20) = 26.72, p= .001, η2= .57,
localization, F(2, 20) = 8.52, p= .001, η2= .47, and the two-way interaction Lat-
eralization ×Type, F(4, 20) = 6.62, p= .001, η2= .41. However, the two grand-
averaged supraliminal/subliminal waves were quite similar: There was no signif-
icant effect for condition, F(1, 20) = 1.02, p= .39, η2= .07. No other effect or
interaction was significant for the ANOVA. Figure 4 shows the peak profiles as
a function of type of emotion.
Inspection of the simple effect of type revealed that N2 was differentiated as
a function of emotional content of faces. A higher negative peak was observed
for fear, F(1, 20) = 6.52, p= .001, η2= .38, and anger, F(1, 20) = 9.14, p= .001,
η2= .40, compared with joy; fear, F(1, 20) = 8.20, p= .001, η2= .33, and anger,
F(1, 20) = 5.98, p= .001, η2= .28, compared with sadness; and fear, F(1, 20) =
11.52, p= .001, η2= .47, and anger, F(1, 20) = 6.04, p= .001, η2= .30, com-
pared with neutral stimuli. For localization, a more posterior (Pz) distribution
was revealed for N2 compared with Fz, F(1, 20) = 12.03, p= .001, η2= .44, and
Cz, F(1, 20) = 5.91, p= .001, η2= .36.
The significant interaction Localization ×Type was subsequently analyzed.
As previously observed in both supraliminal and subliminal conditions, the nega-
tive emotions were more rightly distributed than the positive and neutral stimuli.
The latency dependent variable did not show differences as a function of the
main effect of type, lateralization, and localization, but only of condition. In fact,
as shown in Figure 4, the N2 peak deflection was delayed in the subliminal con-
dition, F(1, 20) = 7.71, p = .001, η2= .41, compared with the supraliminal con-
dition. Whereas subliminal N2 appeared at about 250 ms (M = 248 ms), supral-
iminal ERP variation was at about 220 ms poststimulus.
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P3 effect. We analyzed the P3 effect for peak value and latency measures. The
first mixed-design ANOVA (Condition ×Localization ×Lateralization ×Type)
showed no significant main and interaction effects. Therefore, the direction of the
mean was undifferentiated as a function of the type of emotion, F(4, 20) = 1.06,
p = .38, η2= .14, condition, F(1, 20) = 0.63, p = .47, η2= .06, lateralization, F(1,
20) = 1.39, p = .18, η2= .16, and localization, F(2, 20) = 0.84, p = .30, η2= .10.
In parallel, the latency of the positive ERP effect was not affected by the inde-
pendent variables or by their possible interactions.
By obtaining subliminal and supraliminal ERPs to the same stimuli, we ex-
amined the relationship between conscious and unconscious affective processes.
Responses to stimuli in the subliminal and supraliminal conditions were compa-
rable in waveform. First, they were similar for observable standard components,
N2 and P3 effects. Second, they shared early differentiation of the affective stim-
uli. Based on this analysis, similarities in processing between supraliminal and
subliminal stimulation can be assessed: Substantial analogies in the subliminal
and supraliminal ERP component structure were well-founded, suggesting that
similar neural activity is involved (Shevrin, 2001; Snodgrass, 2000). Specifical-
60 Genetic, Social, and General Psychology Monographs
FIGURE 4. Grand-averaged waveforms for supraliminal and subliminal con-
100 200 300 400 500
Supraliminal Subliminal
N2 P3
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ly, the resemblance between the classical N2 and its subliminal analogue sug-
gests that they are of similar origin in both experimental conditions. It suggests
that analogous neutral pathways were engaged during the two conditions, imply-
ing that some mental processes may operate on the same basis whether or not
conscious perception is involved (Balconi, 2003; Epstein, 1994; Lazarus, 1991;
Miller, 1996). More specifically, it seems that the information presented to a par-
ticipant under subliminal conditions may be perceived and processed on a high-
er level even if he or she is not aware of this information. Results from studies
that have examined attention and psychophysiological responses to emotional
stimuli show that subliminal stimuli are effective both in capturing attention and
in eliciting autonomic responses (Öhman & Soares, 1998; Regan & Howard,
1995). Both processes appear to have a preattentive origin, because they can be
observed in response to stimuli that are prevented from reaching conscious
An additional result of the present research was the parietal distribution of
subliminal N2 on the scalp. This is an interesting point, specifically if it is com-
pared with the supraliminal stimulation, which showed an analogous posterior
(Pz) localization of the negative peak. This concordance of peak localization
leads to the hypothesis that there is an overlapping cortical source for supralim-
inal and subliminal emotional decoding. Second, a similar direction of ERP dif-
ferences between the emotional expressions was observed. A higher amplitude of
N2 for negative, threatening faces was found compared with positive low-threat-
ening or neutral expressions. Figure 5 displays the peak values as a function of
emotion and condition factors.
Data suggest emotional specificity in subthreshold-elicited different re-
sponses, which indicates that the stimuli can be positively or negatively evaluat-
ed without conscious recognition. Moreover, a main result of the research is the
lateralization effect found as a function of the positive or negative value of emo-
tions. As discussed in Experiment 1, even the subliminal condition shows a clear
right-scalp distribution of the negative faces (fear, anger, and sadness), whereas
positive emotions are preferentially localized on the left. The presence of a
Balconi & Lucchiari 61
anger fear
FIGURE 5. Peak values of N2 as a function of emotion and supraliminal and
subliminal conditions.
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similar effect for subthreshold stimuli may suggest that the right hemisphere effec-
tively discriminates negative emotions from positive faces (Davidson, 1995) and
that this effect is present regardless of the conscious or unconscious condition.
A third main point of the current research is that temporal retardation of the
peak appears to distinguish subliminal from supraliminal information process-
ing. Peak latencies of the corresponding deflections elicited by subliminally pre-
sented stimuli were clearly distinct compared with the latencies of the supralim-
inal N2. To explain the temporal effect observed, we hypothesized that the time
required to elaborate the emotional information might be conditioned by the type
of stimulus viewed. The differences found between the two experimental condi-
tions would depend on the type of processing and, more specifically, on the level
of complexity and of the attentional effort of the cognitive processes implicated.
As ERP provides information regarding the temporal sequence of human infor-
mation processing, further analysis of the time relations between the supralimi-
nal and the subliminal N2 peak latencies might be fruitful in the future. In fact,
as suggested by Brázdil and colleagues (1998), who found different patterns in
mutual time relations in a part of their subliminal sample (in one case delayed
and in the other anticipated), the attention level differences of the participants
could be a valid explanation of the heterogeneous results; this effect must be test-
ed more directly.
Finally, even if we had not found results in favor of lateralization of con-
scious processing, the question of possible lateralization of awareness to the left
side emerges. In fact, Gazzaniga (1993) suggests the crucial role of the left hemi-
sphere for consciousness, whereas Davidson (1995) favors the right hemisphere.
The lateralization findings call attention to possible qualitative differences be-
tween conscious and unconscious affective processing, and this topic has to be
explored systematically.
We described the functional significance of the two ERP variations, N2 and
P3 effects, in the present study. The negative deflection N2 was elicited by the
emotional faces, and, as revealed by the cortical localization of ERP, it has a spe-
cific cortical site because it was more distributed on the posterior areas of the
scalp more than on the frontal areas. However, we found no differences between
the emotional and neutral conditions for P3. The possibility that a cognitive “cor-
tical code” for emotion expression recognition exists is pointed out by our data
on the negative ERP component, which seems to be strictly related to emotional
value of face. This pattern suggests a possible dissociation between a specific vi-
sual mechanism responsible for the encoding of faces and a “higher level” mech-
anism for associating the facial representation with semantic information about
the emotion that face represents, as previously suggested by Bruce and Young
(1998). Second, emotion specificity of N2 was verified as a function of the emo-
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tional content of facial expressions. In fact, the face-sensitive N2 component was
modulated by emotional significance of the face. The peak variability was relat-
ed to the significance of the emotional face, and a broad continuum was observed
inside the emotional universe: Negative high-threatening facial expressions were
discriminated by N2 (higher peak) compared with low-threatening expressions
(lower peak). On the contrary, a general aspecificity of the second positive ERP
effect, P3 variation, was observed, for emotion discrimination. The fact that P3
is insensitive to emotional expression could thus indicate that this component re-
flects facial processing at a different stage of face decoding compared with N2.
On the whole, our results are in line with results from studies that have ex-
amined cognitive and psychophysiological responses to emotional stimuli, which
have shown that such stimuli are effective both in capturing attention and in elic-
iting arousal responses, with a direct effect on ERP variations. Moreover, our re-
sults support the functional significance of facial expressions, given that facial
expressions seem to be intrinsically valenced, possibly serving as simple releas-
ing mechanisms for the approach or avoidance response. The importance of an
individual’s response to emotional stimulus is related to the important adapta-
tional function of emotion to facilitate appropriate responses to environmental
stimuli of major significance for survival and well-being. Therefore, the detec-
tion of intrinsic threatening power comprehends the facial stimulus in terms of
preferences or aversion, a process that produces different results in arousal and
ERP correlates (Ellsworth & Scherer, 2003).
Another main result of our research was the localization effect found for
positive and negative categories of emotions. In line with the valence hypothesis,
the right hemisphere primarily mediates negative rather than positive emotions,
although previously it was mainly observed for frontal cortical sites (Davidson,
1993). The left–right lateralization effect in the present study found for both con-
scious and unconscious stimulation is an interesting result that requires a careful
investigation, and the asymmetrical distribution of emotions on the scalp as a
function of their positive–negative value is a fact to be further analyzed.
Third, peak profile was unaffected by the stimulation condition (supralimi-
nal vs. subliminal); however, quite similar ERP variations were found for con-
scious and unconscious processes. From this point of view, what are the impli-
cations of the reported research? From a methodological standpoint, the research
provides strong evidence for the assertion that unconscious processes are instan-
tiated in electrophysiological events. Subliminal ERPs appear to have the same
component structure as supraliminal ERPs and may serve as markers for uncon-
scious process. From the present results, we can infer that subliminal compo-
nents are correlated with psychological processes occurring supraliminally. In
fact, our findings suggest that at least some of our understanding of the supral-
iminal N2 effect may also apply to the unconscious N2 effect.
However, to the degree that there is consistency between the neural activa-
tion during conscious and unconscious emotional reactions, does this represent
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fundamentally similar cognitive activity? Or, in other words, what is the intrinsic
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Final revision accepted September 20, 2005
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... Further, mid-latency patterns have been pinpointed that may be specific markers of subliminal compared to optimal processing (Liddell et al., 2004;Williams et al., 2004). Conversely, late processing (~300-600ms) has rather been associated with elaborate cortical processes during optimal negative processing, such as analysis, integration and memory, which are likely to differ with distinct visual awareness (Balconi & Lucchiari, 2005Liddell et al., 2004;Pegna, Landis, & Khateb, 2008;Williams et al., 2004). Notably, while ERPs can provide temporal information on neural responses to presented stimuli, the spatial topography of potentials measured in the sensorspace (i.e. at the electrodes) does not readily reveal which brain structures generate these potentials, i.e. the sourcespace (Grech et al., 2008;Hämäläinen & Ilmoniemi, 1994). ...
... Conversely, enhanced late neural patterns (300-600ms) have been primarily associated with elaborate cortical processing and conscious representations of optimal negative material (Bradley, 2009;Carlson & Reinke, 2010;Carretié et al., 2004;Carretié et al., 2001;Halgren & Marinkovic, 1995;Liddell et al., 2004;Pegna et al., 2011;Williams et al., 2004). Research has reported enhanced late amplitudes Liddell et al., 2004;Nakajima et al., 2015), for optimal negative compared to neutral images which were absent at subliminal exposure (Balconi & Lucchiari, 2005Liddell et al., 2004;Pegna et al., 2008;Williams et al., 2004). Further, late amplitudes have been found to correlate with increasing stimulus visibility (Pegna et al., 2008), prompting conclusions that neural responses in late components may be direct correlates for optimal negative processing. ...
... Results showed that rDLPFC inhibition compared to sham increased early occipito-parietal and midlatency temporal activations for fearful faces. Such activity has been previously associated with automatic processing of subliminal and optimal negative images (Balconi, 2006;Balconi & Lucchiari, 2005Eimer et al., 2008;Kim et al., 2013;Liddell et al., 2004;Nakajima et al., 2015;Pegna et al., 2008;M. L. Smith, 2012;Williams et al., 2004), suggesting that top-down input may modulate the automatic feedforward process of negative information (Pessoa et al., 2010;. ...
This thesis examined the effects of higher cognitive mechanisms on the automatic and elaborate elicitation of motivational behaviours by visual material presented in absence (i.e. subliminal stimuli) and presence of visual awareness (i.e. optimal stimuli), respectively. With the aim of teasing apart automatic and elaborate approach and withdrawal behaviours, the first study measured self-pain tolerance, intensity and unpleasantness during the Cold Pressor Test (within-subjects) in healthy participants (N=155) before and after passive viewing of negative or vicarious pain images at subliminal or optimal exposure (between-subjects). As a further step, the second study examined the neural and behavioural effects of right dorsolateral prefrontal cortex (rDLPFC) inhibition on automatic and elaborate negative processing pathways. For this purpose, encephalographic (EEG) neural responses (within-subjects) were recorded while healthy participants (N=38) passively viewed negative and neutral images presented at subliminal and optimal exposure (within-subjects) before and after right dorsolateral prefrontal cortex (rDLPFC) inhibition or sham via repetitive transcranial magnetic stimulation (rTMS) (between-subjects). EEG event-related potentials were analysed for early (80-120ms), mid (120-300ms) and late time-windows (300-600ms). Participants completed behavioural attention and affective tasks after the trial presentation (N=48). Findings showed that both subliminal and optimal negative images as well as optimal vicarious pain elicited increased self-pain sensitivity, reflecting automatic and elaborate withdrawal behaviours, respectively. Conversely, subliminal vicarious pain decreased self-pain sensitivity, reflecting automatic approach responses (Study 1). Furthermore, two networks of automatic negative processing emerged: temporal pathways showing increased early and mid-latency activity specific to subliminal negative images, which remained unaffected by rDLPFC inhibition; and occipito-parietal pathways, showing increased mid- and late latency activity for negative images after rDLPFC inhibition, independent from visual awareness. Moreover, rDLPFC inhibition increased late frontal activity for optimal negative images at elaborate processing stages. This was associated with decreased withdrawal behaviours; specifically, attenuated negative priming and faster attention disengagement (Study 2). These results indicate that in absence of visual awareness, automatic motivational behaviours may be modulated according to whether visual material reflects self-oriented (i.e. negative) or other-oriented threat (i.e. vicarious pain), thereby requiring withdrawal or approach and empathic understanding that enhance individual or group survival, respectively. Automatic negative processing may follow multiple neural pathways, which underpin automatic attention orienting (temporal network) and stimulus encoding (occipito-temporal network). The occipito-temporal network, in particular, may integrate bottom-up and top-down input, thereby permitting disinhibited higher cognitive processes involved in top-down regulation to exert early influence on automatic activation of approach and withdrawal behaviours. In presence of visual awareness, disinhibition of the frontal control network reduced withdrawal responses, confirming its role in the regulation of elaborate motivational behaviours. It seems likely that vicarious pain processing occurs along similar pathways, albeit with different behavioural consequences; however, such speculation requires future investigation. The distinct networks facilitating healthy automatic and elaborate stimulus processing represent a platform for further exploration, including the detection of aberrant neural activity in clinical disorders characterized by dysfunctional approach-withdrawal behaviours. Given the modulatory effects of top-down regulation on both automatic and elaborate processing, it is tentatively suggested that cognitive management strategies that enhance affective and attentional control may decrease excessive withdrawal responses. Future research may use integrative behavioural-neuroimaging methods to determine relevant boundary conditions of automatic and elaborate processing in healthy and clinical populations.
... Particularly for pharmacological interventions like testosterone, which modulates multiple parts of the emotion circuitry (see e.g.,Bos et al., 2012;van Wingen et al., 2010), effects are unlikely to be bound to single ERP peaks. Previous ERP studies have shown increased amplitudes for subliminally presented angry (compared to neutral) faces especially on early components such as the frontocentral P2 or VPP TESTOSTERONE AFFECTS EARLY THREAT PROCESSING 5 (vanPeer et al., 2010), the N2 (Balconi & Lucchiari, 2005), and the EPN (Mühlberger et al., 2009). Some studies with supraliminal stimuli suggest that this effect may be amplified in socially anxious compared to non-anxious participants (e.g., P1 amplitude:Mueller et al., 2009;Hagemann, Straube, & Schulz, 2016;N170 amplitude: Kolassa & Miltner, 2006;Wieser, Pauli, Reicherts, & Mühlberger, 2010; see also P3/LPP amplitude:Moser, Huppert, Duval, & Simons, 2008;Hagemann et al., 2016). ...
... However, we did not find group differences in the processing of angry faces (see alsoMühlberger et al., 2009, but cf. Kolassa & Miltner, 2006Schulz et al., 2013), or enhanced amplitudes for angry compared to neutral or happy faces (cf.,Balconi & Lucchiari, 2005van Peer et al., 2010). Overall, ERP evidence for hypervigilance to social threat in social anxiety is still rather inconsistent (seeSchulz et al., 2013for a review). ...
... Further research is needed to assess the ecological validity of our findings by comparing them with the effects of endogenous testosterone increases. Third, we used a subliminal version of the Emotional Stroop task, as previous studies suggested that effects of testosterone are more pronounced for preconscious processing of threat (Van Honk et al., 2000, 2005). However, the backward masking assumedly prevented further conscious or controlled processing of the stimuli (Van Honk et al., 2000;van Peer et al., 2010), which may explain the absence of ERP effects in later processing stages. ...
Testosterone plays an important role in social threat processing. Recent evidence suggests that testosterone administration has socially anxiolytic effects, but it remains unknown whether this involves early vigilance or later, more sustained, processing-stages. We investigated the acute effects of testosterone administration on social threat processing in 19 female patients with Social Anxiety Disorder (SAD) and 19 healthy controls. Event-related potentials (ERPs) were recorded during an emotional Stroop task with subliminally presented faces. Testosterone induced qualitative changes in early ERPs (<200ms after stimulus onset) in both groups. An initial testosterone-induced spatial shift reflected a change in the basic processing (N170/VPP) of neutral faces, which was followed by a shift for angry faces suggesting a decrease in early threat bias. These findings suggest that testosterone specifically affects early automatic social information processing. The decreased attentional bias for angry faces explains how testosterone can decrease threat avoidance, which is particularly relevant for SAD.
... In human relationships, the face is a significant social stimulus [50][51][52][53][54]. Face processing may be separated into a first perceptive phase, in which the person completes the "structural codes" of face and a second phase in which the subject completes the "expression code" implicated in the decoding of emotional facial expressions [55]. The first is thought to be processed separately from complex facial information such as emotional meaning [56][57][58][59][60][61]. Here we argue that the simple presentation of a face receiving painful or non-painful stimulation in the context of pain observation in others activates frontal brain regions connected to emotional regulation of the empathic response, more than somatosensory areas. ...
This research explored how the manipulation of interoceptive attentiveness (IA) can influence the frontal (dorsolateral prefrontal cortex (DLPFC) and somatosensory cortices) activity associated with the emotional regulation and sensory response of observing pain in others. 20 individuals were asked to observe face versus hand, painful/non-painful stimuli in an individual versus social condition while brain hemodynamic response (oxygenated (O2Hb) and deoxygenated hemoglobin (HHb) components) was measured via functional Near-Infrared Spectroscopy (fNIRS). Images represented either a single person (individual condition) or two persons in social interaction (social condition) both for the pain and body part set of stimuli. The participants were split into experimental (EXP) and control (CNT) groups, with the EXP explicitly required to concentrate on its interoceptive correlates while observing the stimuli. Quantitative statistical analyses were applied to both oxy- and deoxy-Hb data. Firstly, significantly higher brain responsiveness was detected for pain in comparison to no-pain stimuli in the individual condition. Secondly, a left/right hemispheric lateralization was found for the individual and social condition, respectively, in both groups. Besides, both groups showed higher DLPFC activation for face stimuli presented in the individual condition compared to hand stimuli in the social condition. However, face stimuli activation prevailed for the EXP group, suggesting the IA phenomenon has certain features, namely it manifests itself in the individual condition and for pain stimuli. We can conclude that IA promoted the recruitment of internal adaptive regulatory strategies by engaging both DLPFC and somatosensory regions towards emotionally relevant stimuli.
... Consistent with this idea, findings of pre-attentive fear-and anger-detection derived from behavioral approaches have been reinforced by neuroimaging techniques, which likewise suggest that at least some emotional information can be extracted from faces in the absence of conscious awareness, as inferred from relevant changes in neural activity (Balconi, 2006;Balconi and Lucchiari, 2005;Vuilleumier et al., 2002;Williams et al., 2004). ...
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A growing literature suggests that facial expression of certain emotions, such as fear or anger, may be pre-consciously detectable by observers, possibly facilitating more rapid neural processing for adaptive reasons. Might facial expressions of pain be similarly privileged for pre-conscious detection and processing? In this paper, we provide theoretical reasons for and against this proposition and critically analyze the small amount of empirical data on the question that has been published to date. Although we argue that these data point to a tentative "yes," we also highlight experimental design features that we think could be strengthened going forward.
... Painful scenes were much more varied than nonpainful scenes. They therefore captured more attentional resources [65], and received more cognitive resources [26]. It might be the reason why the amplitude elicited by the painful stimuli was significantly larger than that elicited by the nonpainful stimuli. ...
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Facial expressions are deeply tied to empathy, which plays an important role during social communication. The eye region is effective at conveying facial expressions, especially fear and sadness emotions. Further, it was proved that subliminal stimuli could impact human behavior. This research aimed to explore the effect of subliminal sad, fearful and neutral emotions conveyed by the eye region on a viewer's empathy for pain using event-related potentials (ERP). The experiment used an emotional priming paradigm of 3 (prime: subliminal neutral, sad, fear eye region information) × 2 (target: painful, nonpainful pictures) within-subject design. Participants were told to judge whether the targets were in pain or not. Results showed that the subliminal sad eye stimulus elicited a larger P2 amplitude than the subliminal fearful eye stimulus when assessing pain. For P3 and late positive component (LPC), the amplitude elicited by the painful pictures was larger than the amplitude elicited by the nonpainful pictures. The behavioral results demonstrated that people reacted to targets depicting pain more slowly after the sad emotion priming. Moreover, the subjective ratings of Personal Distress (PD) (one of the dimensions in Chinese version of Interpersonal Reactivity Index scale) predicted the pain effect in empathic neural responses in the N1 and N2 time window. The current study showed that subliminal eye emotion affected the viewer's empathy for pain. Compared with the subliminal fearful eye stimulus, the subliminal sad eye stimulus had a greater impact on empathy for pain. The perceptual level of pain was deeper in the late controlled processing stage.
... The N200 is a negative ERP component peaking 200-300 ms post stimulus (Squires et al., 1976(Squires et al., , 1977. Numerous studies have shown that the N200 is related to the emotional content of stimuli (Balconi and Lucchiari, 2005;Balconi and Pozzoli, 2009;Kotz, 2010, 2011). Kanske and Kotz (2011) used an emotional valence flanker task where participants responded to the print color of the target word where it was either neutral or emotional and found a difference in N200 amplitude for emotional versus neutral trials. ...
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The urge people get to squeeze or bite cute things, albeit without desire to cause harm, is known as “cute aggression.” Using electrophysiology (ERP), we measured components related to emotional salience and reward processing. Participants aged 18–40 years (n = 54) saw four sets of images: cute babies, less cute babies, cute (baby) animals, and less cute (adult) animals. On measures of cute aggression, feeling overwhelmed by positive emotions, approachability, appraisal of cuteness, and feelings of caretaking, participants rated more cute animals significantly higher than less cute animals. There were significant correlations between participants’ self-report of behaviors related to cute aggression and ratings of cute aggression in the current study. N200: A significant effect of “cuteness” was observed for animals such that a larger N200 was elicited after more versus less cute animals. A significant correlation between N200 amplitude and the tendency to express positive emotions in a dimorphous manner (e.g., crying when happy) was observed. RewP: For animals and babies separately, we subtracted the less cute condition from the more cute condition. A significant correlation was observed between RewP amplitude to cute animals and ratings of cute aggression toward cute animals. RewP amplitude was used in mediation models. Mediation Models: Using PROCESS (Hayes, 2018), mediation models were run. For both animals and babies, the relationship between appraisal and cute aggression was significantly mediated by feeling overwhelmed. For cute animals, the relationship between N200 amplitude and cute aggression was significantly mediated by feeling overwhelmed. For cute animals, there was significant serial mediation for RewP amplitude through caretaking, to feeling overwhelmed, to cute aggression, and RewP amplitude through appraisal, to feeling overwhelmed, to cute aggression. Our results indicate that feelings of cute aggression relate to feeling overwhelmed and feelings of caretaking. In terms of neural mechanisms, cute aggression is related to both reward processing and emotional salience.
... However, the emotional context did not significantly modulate the electrophysiological response to auditory distraction, contrasting with previous studies ( Domínguez-Borràs et al., 2008;Garcia-Garcia et al., 2008) which found an enhancement of the visual P300 for emotionally negative stimuli ( Domínguez-Borràs et al., 2008). Nevertheless, in studies using faces, some authors have found visual P300 enhancement by fearful faces ( Luo et al., 2010), while others reported no changes in P300 amplitude ( Balconi and Lucchiari, 2005) as in the present study. Importantly, in the present study, the emotional content of the images was not relevant for the task. ...
Steroid hormones are important regulators of brain development, physiological function, and behavior. Among them, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEAS) also do modulate emotional processing and may have mood enhancement effects. This chapter reviews the studies that bear relation to DHEA and DHEAS [DHEA(S)] and brain emotional processing and behavior. A brief introduction to the mechanisms of action and variations of DHEA(S) levels throughout life has also been forward in this chapter. Higher DHEA(S) levels may reduce activity in brain regions involved in the generation of negative emotions and modulate activity in regions involved in regulatory processes. At the electrophysiological level, higher DHEA-to-cortisol and DHEAS-to-DHEA ratios were related to shorter P300 latencies and shorter P300 amplitudes during the processing of negative stimuli, suggesting less interference of negative stimuli with the task and less processing of the negative information, which in turn may suggest a protective mechanism against negative information overload. Present knowledge indicates that DHEA(S) may play a role in cortical development and plasticity, protecting against negative affect and depression, and at the same time enhancing attention and overall working memory, possibly at the cost of a reduction in emotional processing, emotional memory, and social understanding.
... La letteratura ci suggerisce che ci sia una relazione tra l'esperienza dell'empatia emozionale e l'abili- t? di riconoscere le espressioni facciali. Gli stati emotivi sperimentati da- gli altri sono riconoscibili, infatti, leggendo le loro espressioni facciali (Balconi e Lucchiari, 2005;Balconi e Pozzoli, 2009;Hofelich e Preston, 2012). ...
Neuromanagement is a research field where neuroscience methods and techniques are applied to management. The paper wants to sketch an overview of the state of the art of research in this field Neuromanagement aims at supporting changes within organizations according to internal and external needs. Neuroscience methods are in this perspective, useful in overcoming simplistic predictive models from management tadition thanks to the opportunities offered by the analysis of implicit measures, which reflect the importance of unconscious mechanisms and emotional processes together with rational and aware processes. In the management world, "explicit" and "implicit" dimensions coexist While introducing the topic of implicit processes, we will then discuss even emotional and non-rational dimensions of human behaviour. We will also focus on non-verbal dimensions of communication and on the role of facial mimicry, which is a crucial channel for social interaction in corporate contexts. Finally, the verbal component of face-to-face interactions integrates the non-verbal dimension, enriching and completing the communicative process towards the creation of meaning.
Purpose Epilepsy is a common neurological disorder that may be complicated by neurobehavioral comorbidities. In a previous study, we identified impairment of empathy in patients with idiopathic generalized epilepsy (IGE). However, the temporal processing of empathy in patients with IGE is not well understood. Methods We investigated empathy for pain and self-reported empathy in 21 patients with IGE and 22 healthy control subjects. All study participants were required to complete a pain empathy task involving images of individuals in pain and neutral conditions during recording of event-related potentials. Results Compared with the controls, the patients with IGE showed impaired cognitive empathy but intact emotional empathy on the Chinese version of the Interpersonal Reactivity Index; they also had normal N1, N2, and late positive potential (LPP) but lower P3 amplitudes evoked by depictions of pain in others when compared with neutral images during the pain judgment task; the difference in the effects of pain empathy on the pain task between the IGE group and the control group was statistically significant. Conclusion These results indicate that later processing of pain empathy is impaired but early processing is intact in patients with IGE. The present study extends the findings of our previous behavioral study by providing solid evidence of impaired empathy in patients with IGE at the neural processing level.
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The dorsolateral prefrontal cortex (DLPFC) plays a key role in the modulation of affective processing. However, its specific role in the regulation of neurocognitive processes underlying the interplay of affective perception and visual awareness has remained largely unclear. Using a mixed factorial design, this study investigated effects of inhibitory continuous theta-burst stimulation (cTBS) of the right DLPFC (rDLPFC) compared to an Active Control condition on behavioral (N = 48) and electroencephalographic (N = 38) correlates of affective processing in healthy Chinese participants. Event-related potentials (ERPs) in response to passively viewed subliminal and supraliminal negative and neutral natural scenes were recorded before and after cTBS application. We applied minimum-norm approaches to estimate the corresponding neuronal sources. On a behavioral level, we found evidence for reduced emotional interference by, and less negative and aroused ratings of negative supraliminal stimuli following rDLPFC inhibition. We found no evidence for stimulation effects on self-reported mood or the behavioral discrimination of subliminal stimuli. On a neurophysiological level, rDLPFC inhibition relatively enhanced occipito-parietal brain activity for both subliminal and supraliminal negative compared to neutral images (112–268 ms; 320–380 ms). The early onset and localization of these effects suggests that rDLPFC inhibition boosts automatic processes of “emotional attention” independently of visual awareness. Further, our study reveals the first available evidence for a differential influence of rDLPFC inhibition on subliminal versus supraliminal neural emotion processing. Explicitly, our findings indicate that rDLPFC inhibition selectively enhances late (292–360 ms) activity in response to supraliminal negative images. We tentatively suggest that this differential frontal activity likely reflects enhanced awareness-dependent down-regulation of negative scene processing, eventually leading to facilitated disengagement from and less negative and aroused evaluations of negative supraliminal stimuli.
Emotion and attention heighten sensitivity to visual cues. How neural activation patterns associated with emotion change as a function of the availability of attentional resources is unknown. We used positron emission tomography (PET) and 15O-water to measure brain activity in male volunteers while they viewed emotional picture sets that could be classified according to valence or arousal. Subjects simultaneously performed a distraction task that manipulated the availability of attentional resources. Twelve scan conditions were generated in a 3 x 2 x 2 factorial design involving three levels of valence (pleasant, unpleasant and neutral), two levels of arousal and two levels of attention (low and high distraction). Extrastriate visual cortical and anterior temporal areas were independently activated by emotional valence, arousal and attention. Common areas of activation derived from a conjunction analysis of these separate activations revealed extensive areas of activation in extrastriate visual cortex with a focus in right BA18 (12, -88, -2) (Z=5.73, P < 0.001 corrected) and right anterior temporal cortex BA38 (42, 14, -30) (Z=4.03, P < 0.05 corrected). These findings support an hypothesis that emotion and attention modulate both early and late stages of visual processing.
Three studies investigated whether individuals preferentially allocate attention to the spatial location of threatening faces presented outside awareness. Pairs of face stimuli were briefly displayed and masked in a modified version of the dot-probe task. Each face pair consisted of an emotional (threat or happy) and neutral face. The hypothesis that preattentive processing of threat results in attention being oriented towards its location was supported in Experiments 1 and 3. In both studies, this effect was most apparent in the left visual field, suggestive of right hemisphere involvement. However, in Experiment 2 where awareness of the faces was less restricted (i.e. marginal threshold conditions), preattentive capture of attention by threat was not evident. There was evidence from Experiment 3 that the tendency to orient attention towards masked threat faces was greater in high than low trait anxious individuals.
We addressed the questions whether stimuli presented below the threshold of verbal awareness are nevertheless perceived and whether there are perceptual differences between the two cerebral hemispheres. Pictures of line drawn objects and animals were subliminally presented to each visual half-field for subsequent identification in a form as fragmented as possible. The performance of 40 healthy subjects was compared to that of 63 controls. Whereas identification performance after blank presentation in the experimental group did not differ from that of controls, identification in a significantly more fragmented form was achieved after the presentation of the complete picture. This effect, however, occurred only after subliminal stimulation in the left visual field, i.e., of the right hemisphere. Our results show that (i) pictures presented below the threshold of verbal awareness can be perceived, and (ii) that only the right hemisphere can perceive them and make use of the perception. It remains an open question whether this kind of hemispheric specialization represents a right hemisphere dominance for subliminal perception or reflects an inability of the left hemisphere to access and behaviorally use unaware percepts via fragmented picture identification, for which a right hemisphere advantage is known.