INTRODUCTION. The influence of non-conscious emotional qualities (valence and arousal) in decision making RESULTS AND DISCUSSION:
and in preference for a neutral stimuli associated are studied.
The behavioral indicator used was the preference choice for a neutral mask stimuli that was specifically associated
with a subliminal emotion category, and differed between subliminal emotions. Besides, it was supposed a bivariate
model of preferences allowing the expression of the liking and the rejection (disliking) subjective evaluations,
respectively: So each one of the four mask stimuli were evaluated in forced choice response for the most preferred;
and in another forced choice question the for most “disliked”.
Experimental paradigm of backward and forward masking of emotion visual stimuli was used in four conditions
EEG –ERPs were recorded for each stimuli category. Selected pictures from IAPS were used as emotional primes,
presented during 17 ms, preceded and followed by neutral mask stimuli (167 ms). The masks consisted in four
neutral abstract pictures and each mask was associated with a subliminal emotion category (figure 1)
In the first experiment, valence effects were examined using four categories of
subliminal stimuli selected from IAPS for valence and arousal normative
ratings: positive, negative, neutral and faint (in this case, a grey slide was
subliminally presented).
In a second experiment the effects of arousal raised by the results obtained were
tested using two valences (positive and negative) with two arousal levels (high
and low) as subliminal emotion categories
RESULTS. In the first experiment significant preferences ratings were
obtained for positive and faint conditions. Rejection (or disliking) ratings were
heist for negative and also for faint conditions, nevertheless non-significant.
These results suggested an effect of valence. Faint “liking” ratings were
interpreted as an effect of activation/attention due to the rarity/low frequency
of this condition (among the other three emotion experimental conditions).
Mask
167ms
Mask
167ms
Positive Stimulus
17ms
Neutral Stimulus
17ms
Mask
167ms
Mask
167ms
Mask
167ms
Mask
167ms
Faint Stimulus
17ms
Negative Stimulus
17ms
Mask
167ms
Mask
167ms
Figure 1. Sequence of stimuli presentation on
backward and forward masking paradigms. For each
emotion condition a group of 20 emotion pictures
were selected from IAPS and presented associated
with the respective mask stimuli. Subjects were asked
to count the stimuli and had to evaluate the neutral
mask in random intervals during the presentation (60
presentations for each condition). In this picture is
illustrated the study 1. The procedure for study 2 was
identical, differing emotion categories.
In the second experiment preferences ratings were higher for positive low arousal and rejection rates were
more frequent for positive high arousal which suggested an effect of arousal in positivity – nevertheless in
the different direction that was previously expected. Among all, subjects tended to prefer low arousing
positive stimulation in the context of subliminal priming stimulation.
Electrophysiological signals (not reported here), ERPs late positive potentials amplitude (see figure 2) was
higher for liked stimuli category in Fz EEG channel (IS 10/20; Averaging and regression to the 200 ms
baseline separately for each subliminal category).
Figure2. Fz EEG derivation, ERPs grand average
waveforms (12 subjects). Red line plot denotes the ERP
waveform elicited by “liked stimuli”; black line stands
for disliked stimuli. Amplitude and time calibration are
indicated in the figure.
RESULTS AND DISCUSSION.
In previous studies we demonstrated the effects of subliminal emotion stimuli valence on subjective
preferences of masks specifically associated with an emotion category (positive, negative, neutral and faint).
Study 1 pursued with a larger sample. Results of question 1, “Liking forced choice response”, are presented
in table 1. As can be seen, the most frequently preferred was the mask associated to the faint condition
(M=3,89; SD=4,6), followed by the mask associated to the positive stimulation (M=3,16; SD=3,52). The results
of question 2, disliking forced choice response, the most frequently disliked condition was negative valence
(M=3,76; SD=4,29) followed by faint stimulation (M=3,5; SD=4,3) are presented in table 2.
Table 1. Mean frequency and standard
deviation of liking responses of the four
subliminal stimuli conditions (study1).
Mean
SD
Like
3,16 (/12)
3,52
Positive
2,04 (/12)
2,55
Neutral
2,91 (/12)
3,97
Negative
3,89 (/12)
4,6
Faint
Table 2. Mean frequency and standard
deviation of disliking responses of the
four subliminal stimuli conditions (study
1).
Dislike
Positive
Neutral
Negative
Faint
Mean
SD
2,82
3,99
1,91
3,28
3,76
4,49
3,51
4,33
Table 3. Mean frequency and standard deviation of liking
responses of the four subliminal stimuli conditions (Study 2).
Like
Positive Low Arousal
Positive High Arousal
Negative Low Arousal
Negative High Arousal
Mean
SD
4.89
3.41
2.19
3.13
2.07
2.09
2.81
2.69
These results were interpreted as suggesting an expectable effect of rarity or low probability of stimuli (within the
experience’ paradigm). The faint condition, was the only one among the other three where no subliminal complex stimuli
was presented. This made faint condition a rare or improbable condition (emotion subliminal stimuli conditions had the
probability of ¾ and the no subliminal stimuli condition occurred with probability of ¼). This effect of improbability or
deviation could induce activation /attention processes. In our experimental paradigm we interpreted this way the higher
rate of preference responses, either liking or disliking for the mask associated with faint subliminal stimulation.
Among these data another result that can be interpreted as reflecting arousal/attention processes consists on the lowest
ratings of neutral category both on question 1 (liking) and on question 2 (disliking): These low ratings can be associated to the
low arousal of neutral valence.
The expected effects of valence/arousal interaction were found in the higher frequency of liking positive valence and also the
higher preference of disliking negative valence.
Although we were addressing the effects of valence, the results raised the issue of arousal effect in preference responses
between the four subliminal stimulation conditions: the high frequency of faint in liking and disliking questions, respectively
in different subjects, and in the low frequency of neutral preferences in both liking and disliking judgements.
Even the expected effect of valence, liking positive and disliking negative could be interpreted as an effect of valence and
arousal interaction.
Results of the second experiment. subjective preferences of masks specifically associated with a subliminal emotion
stimuli category: Positive Low Arousal (PL) and Positive High Arousal(PH), Negative Low Arousal (NL) and Negative High
Arousal (NH). The objective was to clarify the hypothesis about the contribution of arousal - valence interaction in
subliminal emotion preference. Table 3 presents the frequency of preference liking responses in each experimental condition:
the mask associated to the positive, low arousal emotion stimulation condition was the most frequently selected (Anova
repeated measures performed over Liking rates for the four experimental subliminal conditions allowed significant results,
Greenhouse test for sphericity violations, F (2.339; 60.822) = 4.190; p< 0.012. Pairwise comparisons showed that the frequency
of “liking” positive low arousal stimulation was significantly higher than the results obtained in the other conditions,
excluding negative high arousal stimulation).
In other studies (in preparation) the possible meaning of these behavioral data were studied correlating preferences
responses with personality test Clinical Outcome Routine Evaluation – Outcome Measure (CORE-OM), Brief Symptom
Inventory (BSI) and Millon Clinical Multiaxial Inventory-III (MCMI-III).
In these latter studies it was found that the preference reaction toward positive low arousal stimulation was sensible to the
mood state of the subjects, the correlation between the subjective preference for the PL subliminal stimulation and the
depression scale from BSI was negative (-0.380, p<0.05). This were interpreted as an expression of depressive mood low
reactivity to positive stimulation.
In the same line of reasoning, it were found positive correlations between disliking PL and depression from BSI (0.366,
p<0.05) and passive-aggressive clinical personality pattern from MCMI-III (0.433, p<0.05). An expression of disliking PL
stimulation seems to indicate a tendency to have a negative vision of him/herself and social environment.
Liking NH subliminal stimulation was positively correlated with schizoid clinical personality pattern from MCMI-III (0.449,
p<0.05). Disliking this stimulation was negatively correlated with antisocial clinical personality pattern from MCMI-III (0.363, p<0.05). Liking NH stimulation indicates a difficulty in the engagement of social interactions and maintenance of
affects. While disliking NH is not associated with difficulties in forming and maintain significant and affective interactions.