Emotion Ownership: Different Effects on Explicit Ratings and Implicit Responses

doi:10.4236/psych.2013.43A032

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Psychology

2013. Vol.4, No.3A, 213-216

Published Online March 2013 in SciRes (http://www.scirp.org/journal/psych) http://dx.doi.org/10.4236/psych.2013.43A032

Emotion Ownership: Different Effects on Explicit Ratings

and Implicit Responses

Peter Walla1*, Lucy Rosser1, Janka Scharfenberger2, Cornelia Duregger1,

Shannon Bosshard1

1School of Psychology, Centre for Translational Neuroscience and Mental Health, University of Newcastle,

Newcastle, Australia

2Faculty of Psychology, University of Vienna, Vienna, Austria

Email: *[email protected]

Received October 10th, 2012; revised November 16th, 2012; accepted December 15th, 2012

This study is based on the idea that emotion-related processing happens on various different levels.

Common methods that are used to measure different aspects of emotion-related processing exhibit spe-

cific sensitivities to one or the other of these separate processing levels. Here, the hypothesis was tested

that explicit and implicit measures of emotion-related processing are differently influenced by self-refer-

enced versus unreferenced emotion. The explicit measure was self reported valence and the implicit

measure was startle reflex modulation. In one session, emotional scenes were paired with short sentences

inducing self-reference (e.g. “this dog will attack you” written underneath the image of an aggressive dog),

while in another session, emotional scenes were presented without any reference. During both sessions

explicit as well as implicit responses were collected. Self-referenced unpleasant images were rated more

negative and self-referenced pleasant images were rated more positive than images with no reference. In

contrast, the implicit measure indicated greater startle responses related to self-reference regardless of

emotion category. Under the common assumption that greater startle responses reflect increased affective

negativity, this means that self-referenced pleasant images elicited more negative implicit affect than un-

referenced pleasant images. However, in both cases (self-referenced and unreferenced) startle responses

demonstrated valence depended modulation as expected. Thus, in our study startle responses demon-

strated sensitivity to affective valence as well as self-reference. It is concluded that self-reference is linked

to increased motivation, which in turn has been reported to be detectable via startle reflex modulation

(SRM) as well.

Keywords: Emotion; Ownership; Self-Reference; Implicit Responses; Explicit Responses

Introduction

A new line of research follows the notion that there is more

to emotion than subjective feeling. In their book chapter, Walla

and Panksepp (2012) propose that an emotion is the conse-

quence of affective processing and that affective processing can

occur without generating an emotion. Based on a hierarchical

mind model (e.g. Panksepp, 2011; Panksepp & Solms, 2011;

Walla & Panksepp, 2012) there is at least three different proc-

essing levels on which affective processing can be influenced

by simultaneous other processes. For example, one of these si-

multaneous processes can be self-reference. Self-reference is

the process in which an individual, in this case a participant, is

referred to within the context of a situation. Self-reference, or in

other words mere ownership, (e.g. my garden) was found to

elicit distinct brain activity, which is significantly different

from brain activity reflecting somebody else’s ownership (his

garden; Walla et al., 2007, 2008). Only recently has the influ-

ence of self-reference on the processing of emotional words

(e.g. my fear) been investigated with both electroencephalo-

graphy (EEG) (Herbert et al., 2011a) and functional Magnetic

Resonance Imaging (fMRI; Herbert et al., 2011b). Both studies

revealed similar principle ownership effects as well as emotion-

specific self-reference effects. In particular, words of a positive

nature elicited the strongest brain activities in the amygdala and

the insular cortex when self referenced. Furthermore, a word

recall task showed that self-referenced pleasant words were

better recalled than unreferenced words. This indicates that

affective content is differently processed depending on whether

it is linked to the self or not.

The present study is meant to further investigate this issue by

using emotionally evocative scenes. It is assumed that emotion-

ally laden images more directly elicit emotion responses com-

pared to emotion words. To elicit self-reference, images were

shown simultaneously with short sentences. For example, par-

ticipants were presented with an image of an aggressive dog

together with text stating “This dog will attack you”. For the

current study, we hypothesised that the addition of self-refer-

ence would enhance self-reported valence in both directions.

Thus, self-referenced pleasant scenes were expected to be rated

as more pleasant compared to unreferenced pleasant scenes.

Likewise, self-referenced unpleasant scenes were expected to

be rated as more unpleasant compared to unreferenced un-

pleasant scenes. To test this hypothesis, valence ratings (and

arousal ratings) were collected using the Self Assessment Ma-

nekin (SAM; Bradley & Lang, 1994).

In addition to SAM, electromyography (EMG) was used to

record eye blink-related muscle potential changes elicited

through startle stimulation (startle reflex modulation; SRM).

*Corresponding author.

P. WALLA ET AL.

Previous literature has shown SRM to be sensitive to valence in

numerous studies (Vrana et al., 1988; Lang et al., 1998; Walla,

Brenner, & Koller, 2011). Therefore, it is inferred that SRM is

a suitable method to test whether possible changes in valence

rating performance as a function of self-referenced versus un-

referenced emotion images are associated with matching objec-

tive measures of valence. According to previous studies there is

reason to believe that valence measures via startle reflex modu-

lation do not necessarily match explicitly reported valence rat-

ings (Geiser & Walla, 2011; Junghöfer et al., 2010; Grahl et al.,

2012). If such a discrepancy occurs in this study it may provide

evidence to suggest that startle reflex modulation is also sensi-

tive to aspects that are not necessarily valence-related. It has

been reported that SRM is to some extent also sensitive to mo-

tivation (or arousal), but clear evidence does not exist. If it is

the case that a discrepancy is found in our study, it may im-

prove our understanding of what SRM truly measures. In addi-

tion, it would highlight that there is more to emotion than sub-

jective feeling and finally that different measures are differently

sensitive to the various aspects of emotion-related processing in

the human brain.

Method

Participants

Data from 21 volunteers who participated in our study were

collected. Mean age of all participants was 22.5 years (SD = 4.7)

(8 males). They were all University students, right-handed and

had normal or corrected to normal vision. None of them had

any neuropathological history. They all gave their informed

consent and the project was approved by the ethics committee

of the Newcastle University (Australia).

Stimuli

Emotion images were selected from the International Affec-

tive Picture System (IAPS; Lang, Bradley, & Cuthbert, 2008).

In particular, 90 images were used, of which thirty were un-

pleasant (mean pre-evaluated valence rating = 2.65 (SD = 1.65),

30 were pleasant (mean pre-evaluated valence rating = 7.27

(SD = 1.69) and the remaining 30 were neutral (mean pre-

evaluated valence rating = 4.51 (SD = 1.92). Pleasant and un-

pleasant images had matching pre-evaluated arousal values,

whereas neutral images were slightly less arousing. For each of

the three emotion categories, 15 images were randomly as-

signed to the self-referenced group, whereas the remaining 15

images were kept unreferenced. Self-reference was induced by

generating short sentences (3 to 5 words; e.g. “this surgery is on

you” or “you won this money”) that were displayed underneath

the images. This set of 90 images was counterbalanced with

respect to reference and presentation order to generate 6 differ-

ent lists to be randomly used across all participants.

Procedure

On arrival at the laboratory participants were briefly screened

regarding demographics and pathological history. They were

seated on a comfortable chair and all sensors were attached

while the experiment including all the tasks was explained. For

startle reflex modulation, two electrodes were attached under-

neath the right eye (bipolar recording) and a ground electrode

was placed on the left cheek. Explicit ratings (valence and

arousal) were collected by using the SAM procedure (see.

Bradley & Lang, 1994). Participants viewed a screen (LCD

monitor) on which all images (independent variables) were

presented. Image presentation time was 5 seconds followed by

a 1 second blank screen. Then, the self-assessment manekins

for valence rating appeared (see Bradley & Lang, 1994) until

the response was given (using a computer mouse to click on

one of the numbers between 1 and 9 which appeared on the

screen) (maximum of 5 seconds). After the 1 second blank

screen, the self-assessment manekins for arousal appeared until

the response was given (again by clicking on one of the num-

bers between 1 and 9) (maximum of 5 seconds). The experi-

ment was divided into two blocks with 45 images in each. In

one of the blocks (counterbalanced) all images were associated

with short sentences generating self-reference related to the

emotion content of every image.

Physiological Record i n g s and Data Processing

Startle responses (eye blinks) were elicited by using a 50ms

burst of acoustic white noise (105 dB) delivered through head-

phones. Sound pressure level was controlled with a mobile

measuring device (MicroAMP HA400 by Behringer). Via bi-

polar electromyography (EMG) carried out with the Nexus-10

mobile recording device from Mind Media BV muscle potential

changes of the musculus orbicularis oculi of the left eye of

every study participant were recorded. A dual channel electrode

cable with carbon coating and active shielding technology for

low noise and an additional ground electrode cable were used.

EMG sampling rate was 2048 per s. A band pass filter from 20

Hz to 500 Hz was applied during online recording. Recorded

data were stored on the hard drive of the laptop computer,

which was used for data collection. Offline, raw EMG data

were then recalculated by using the root mean square (RMS)

method to transform EMG signals into amplitudes. All resulting

amplitudes were visually inspected. In case of obviously bad

signal-to-noise ratios respective data were not taken into ac-

count. Only a few missing values occurred, which were re-

placed by means of existing values from each respective condi-

tion. Finally, the resulting amplitudes (dependent variables)

were log-transformed to partial out floor effects before they

were subject to statistical analysis in terms of repeated meas-

ures ANOVA to calculate condition main effects and factor

interactions (with SPSS version 19). Factors were affective ca-

tegory with two levels (pleasant and unpleasant) and factor

reference with two levels (self reference and unreferenced).

Results

Explicit Responses

The mean self reported valence on a scale from 1 to 9 for the

unpleasant affective category without self-reference was 2.43

(SD = .88). For the unpleasant affective category with self-

reference the mean self reported valence was 1.87 (SD = .56).

The mean self- reported valence for the pleasant affective cate-

gory without self-reference was 5.85 (SD = .94) and for the

pleasant affective category with self-reference it was 6.43 (SD

= 1.06). The 2 (2 levels of affective category) × 2 (2 levels of

reference) repeated measures ANOVA revealed a significant

affective category main effect (p < .001). There is a non-sig-

nificant reference main effect (p = .897), which is not surpris-

ing, because self-reference had opposite effects on rating per-

214

P. WALLA ET AL.

formance depending on affective category. However, a highly

significant reference * affective category interaction occurs (p

< .001; Figure 1). Further analysis using t-tests revealed that

for the unpleasant affective category, mean self-reported va-

lence is significantly lower in the case of self-reference (p

< .001), whereas for the pleasant affective category, mean

self-reported valence is significantly higher in the case of self-

reference (p < .001). It can thus be inferred that self-reference

increased affective intensity in both directions. Unpleasant

affective content was rated more unpleasant and pleasant affec-

tive content more pleasant when the affective content was ver-

bally referenced to the self of the observer.

Implicit Responses

The mean eye blink response for the unpleasant affective

category without self-reference was 31.88 μV (SD = 23.1) and

with self-reference it was 33.5 μV (SD = 21.7). For the pleasant

affective category without self-reference the mean eye blink

response was 29.7 μV (SD = 22.5) and with self-reference it

was 32.58 μV (SD = 23.7) (Figure 2). A 2 (2 levels of affective

category) × 2 (2 levels of reference) repeated measures

(a)

(b)

Figure 1.

(a) Depicts the valence associated with unpleasant images when a

self-referenced sentence is present or not (the greater the mean self-

reported valence, the more positive the emotion). Similarly, (b) illus-

trates the explicit ratings of pleasant images with and without the inclu-

sion of a self-referenced sentence.

Figure 2.

This bar graph demonstrates the sensitivity of SRM to not only differ-

entiate between the emotional response associated with pleasant and

unpleasant images, but also its ability to detect the effect of self-refer-

ence regardless of valence.

ANOVA of log-transformed values revealed a significant affec-

tive category main effect (p = .049). A significant reference

main effect (p = .019) was also found, but no significant refer-

ence * affective category interaction occurred (p = .473). These

results demonstrate that self-reference as well as valence cate-

gory modified eye blink responses. Follow-up t-tests revealed

that self-reference modified eye blink responses significantly

only for the pleasant affective category (p = .030), whereas for

the unpleasant affective category this effect was not significant

(p = .233).

Discussion

The current study revealed that participants were seen to rate

pleasant images as more pleasant and unpleasant images as

more unpleasant when these were self-referenced. For both

valence categories these effects were statistically significant.

However, although pleasant images were rated more pleasant

when self-referenced, eye blink responses were potentiated in-

dicating greater affective negativity. Given that eye blink re-

sponses are sensitive in detecting deep affective processes (Vra-

na et al., 1988) it was unexpected to find that the explicit/be-

havioural output showed contradictory effects. Only for the un-

pleasant valence category did we find a match between explicit

rating and eye blink responses, because both measures revealed

increased affective negativity for self-referenced images.

Discrepancies between explicit ratings and objective meas-

ures related to affective content have been described earlier. For

example, Mühlberger et al. (2008) found that explicit pleasant-

ness ratings, while virtually driving through a dark tunnel, did

not always match simultaneously registered startle responses.

Dunning et al. (2010) found a non-linear relationship between

the intensity of angry faces and startle eye blink responses.

Similarly, Walla et al. (2010) found that explicitly stated food

preference did not always match startle responses. Geiser and

Walla (2011) showed that virtually walking through urban en-

vironments can result in different effects depending on explicit

or implicit measures. A recent study revealed that even specific

bottle-shapes can alter startle responses without changing ex-

plicit rating performance (Grahl et al., 2012). It is suggested

that such discrepancies are due to cognitive processing associ-

P. WALLA ET AL.

216

ated with explicit responses that interfere with raw affective

processing. In other words, the valence of cognitively appraised

affective content can be different to the valence of the actual

underlying raw affective content itself. This idea fits well the

emotion-model as proposed by Walla and Panksepp (2012).

Alternatively, one might think that in the current study, eye

blink responses were more reflective of motivation-related

aspects of affective content than valence-related aspects. After

all, the effect of mere self-reference on startle responses did not

depend on condition of emotion. In the pleasant as well as the

unpleasant emotion condition, self-reference resulted in en-

hanced eye blink amplitudes. It may be assumed that motiva-

tional aspects are more pronounced in cases of self-reference

regardless of valence. In fact, it has been reported that SRM

provided an insight into not only the emotional responses to-

ward images, but also motivation related aspects related to im-

ages (Lang et al., 1998; Gard et al., 2007; Grillon & Baas,

2003). In contrast, some authors tended to focus more heavily

on the emotional aspects that SRM is able to measure. This

study revisits the findings of previous literature and supports

the use of SRM as not only a measure of emotion but also a

measure of motivation. This seems reasonable assuming that

self-reference is directly correlated with motivation. The more

an individual’s self is linked with pleasant or unpleasant input

the higher the motivation to become active.

Finally though, it must be emphasised that SRM still pre-

sented the expected valence-related difference between pleasant

and unpleasant images. Regardless of whether self-referenced

or not, pleasant images revealed reduced eye blink responses

and negative images resulted in larger eye blink amplitudes. In

sum, this study provides evidence that SRM is indeed sensitive

to both affective valence and self-reference. Finally, we con-

clude that the present study supports the idea that the various

methods that are used to investigate emotion-related processing

are differently sensitive to different aspects of emotion-related

processing. Due to its objective nature (independent from self

report) it is believed that SRM will be used in various further

applied fields in the future (see Koller & Walla, 2012; Arthur-

Kelly et al., 2012).

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