Consciousness and Cognition 22 (2013) 1231–1238

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Consciousness and Cognition

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More of myself: Manipulating interoceptive awareness byheightened attention to bodily and narrative aspects of the self

1053-8100/$ - see front matter � 2013 Elsevier Inc. All rights reserved.http://dx.doi.org/10.1016/j.concog.2013.08.004

⇑ Corresponding author. Address: Department of Psychology, Royal Holloway University of London, Egham, Surrey, UK. Fax: +44 (0)17844343E-mail address: Vivien.Ainley.2008@live.rhul.ac.uk (V. Ainley).

Vivien Ainley ⇑, Lara Maister, Jana Brokfeld, Harry Farmer, Manos TsakirisDepartment of Psychology, Royal Holloway University of London, UK

a r t i c l e i n f o a b s t r a c t

Article history:Received 24 January 2013Available online 8 September 2013

Keywords:InteroceptionInteroceptive awarenessHeartbeat perceptionBodily selfNarrative selfSelf-focusPerceptual accuracy hypothesis

Psychology distinguishes between a bodily and a narrative self. Within neuroscience, mod-els of the bodily self are based on exteroceptive sensorimotor processes or on the integra-tion of interoceptive sensations. Recent research has revealed interactions betweeninteroceptive and exteroceptive processing of self-related information, for example thatmirror self-observation can improve interoceptive awareness. Using heartbeat perception,we measured the effect on interoceptive awareness of two experimental manipulations,designed to heighten attention to bodily and narrative aspects of the self. Participantsgazed at a photograph of their own face or at self-relevant words. In both experimentalconditions interoceptive awareness was significantly increased, compared to baseline.Results show that attention to narrative aspects of self, previously regarded as relying onhigher-order processes, has an effect similar to self-face stimuli in improving interoceptiveawareness. Our findings extend the previously observed interaction between the bodilyself and interoception to more abstract amodal representations of the self.

� 2013 Elsevier Inc. All rights reserved.

1. Introduction

Although few subjects are more central to human experience than ‘the self’, there has been a lack of consensus on def-initions and means of operationalising the self within philosophy, psychology and neuroscience (Gallagher, 2000; Neisser,2006; Strawson, 1999). The distinction between a bodily and narrative self, first proposed by William James, continues tostructure the debate (James, 1890).

The narrative or autobiographical self, which encompasses stored knowledge of the individual’s past experience andanticipated future, has often been treated within psychology as if it were an amodal, abstract symbolic structure (Gallagher,2000), although a recent taxonomy proposes that the narrative self is grounded in bodily self processes acting upon autobio-graphical memories (Damasio, 2010). By contrast, in neuroscience, models of the material or bodily self have been largelybased on multisensory integration. For example, the exteroceptive senses of touch and vision are crucial to body ownership.Thus in the ‘rubber hand illusion’ (Botvinick & Cohen, 1998) synchronous stroking of a visible rubber hand and the partic-ipant’s own hidden hand produces the illusion of ownership of the fake hand. Similarly, the integration of efferent, re-affer-ent and ex-afferent sensorimotor signals provides our sense of personal agency over our own actions (Blakemore, Wolpert, &Frith, 2002), which may be disrupted in disorders such as schizophrenia.

The interoceptive senses (Cameron, 2002; Vaitl & Schandry, 1995; Ádám, 2010) are also fundamental to the self. ‘Intero-ception’ is defined as ‘‘the afferent information arising from within the body that affects the cognition, or behaviour of anorganism, with or without awareness’’ (Cameron, 2002, p. 271). It has been proposed that our basic feelings of existence

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are underpinned by continuous brainstem mapping of homeostatic information about the interoceptive state of the body(Damasio, 2010), while conscious selfhood is potentially based on the re-representation and integration of interoceptive sig-nals in insular cortex (Craig, 2010). ‘Interoceptive awareness’ differs between individuals and is usually assessed behaviour-ally by a cardiac awareness task (Schandry, 1981; Whitehead & Drescher, 1980). Such tests correlate with sensitivity to otherinteroceptive systems, such as visceral or respiratory awareness (Harver, Katkin, & Bloch, 1993; Herbert, Muth, Pollatos, &Herbert, 2012; Whitehead & Drescher, 1980).

Although theoretical analyses have tended to treat interoceptive and exteroceptive aspects of the bodily self as separatesensory systems, recent research has shown that they are interdependent. The eerie phenomenology of the rubber hand illu-sion depends upon interoceptive processes in the autonomic nervous system (Ehrsson, Wiech, Weiskopf, Dolan, & Passing-ham, 2007). As the illusion takes hold, the skin temperature of the hidden hand falls (Moseley et al., 2008) while histaminereactivity in the concealed hand rises (Barnsley et al., 2012), as if the exteroceptive stimulation causes the autonomic ner-vous system to no longer treat the hand as fully part of the body. Given that the most basic definition of self is ‘‘what theimmune system identifies as belonging to the body’’ (Damasio, 2003), in the rubber hand illusion there is an apparently blur-ring of what the autonomic system regards as a true body part. That interoceptive and exteroceptive processes interact informing the sense of bodily self is further illustrated by research showing that the extent to which individuals experiencethe rubber hand illusion depends on their interoceptive awareness. Thus people who are more accurately aware of theirinternal body signals, are less prone to both the rubber hand illusion (Tsakiris, Tajadura-Jiménez, & Costantini, 2011) andthe ‘enfacement illusion’ (Tajadura-Jiménez, Longo, Coleman, & Tsakiris, 2012; Tajadura-Jiménez & Tsakiris, in press), imply-ing that individuals with low interoceptive awareness might have a more malleable mental representation of the self in re-sponse to exteroceptive signals.

Interoceptive awareness has generally been considered a robust trait variable because experimental attempts to manip-ulate it have often been ineffective (Fairclough & Goodwin, 2007; Khalsa et al., 2008; Stevens et al., 2011). However, twostudies show that interoceptive awareness, measured by heartbeat tasks, can be improved through mirror self-observation.In an early paper by Weisz, Bálazs, and Ádám (1988), the mere presence of a mirror was reported to have improved perfor-mance in one measure of cardiac awareness, although not in another. Recently, Ainley, Tajadura-Jiménez, Fotopoulou, andTsakiris (2012) found that gazing into a mirror significantly improved the accuracy of heartbeat perception in individualswho had initially low interoceptive awareness. A third study (Maister & Tsakiris, in press) has recently demonstrated thatlooking at a photograph of their own face improves the interoceptive awareness of individuals who have below-medianinteroceptive awareness in the baseline (a blank screen). No such improvement was found when participants gazed at a sim-ilar photograph of a gender- and age-matched stranger. These finding can be interpreted with respect to the ‘the perceptualaccuracy hypothesis’ in self-focus research (Silvia & Gendolla, 2001), which proposes that any type of self-focused attentionimproves an individual’s accuracy in judging not only somatic but also cognitive aspects of the self.

Given the importance of interoception to the sense of bodily self, the motivation for the current study was therefore toinvestigate whether the processing of self-related narrative information can bring about improvements in people’s consciousawareness of their internal bodily selves, analogous to the improvements in interoceptive awareness that are induced by theprocessing of physical representations of the bodily self. In this experiment, following the results of Ainley et al. (2012) andMaister and Tsakiris (in press), and in accordance with the perceptual accuracy hypothesis, it was hypothesised that anymanipulation leading to increased self-awareness, focusing on either the bodily or narrative aspects of the self, would feed-back to increased accuracy in the individual’s awareness of internal bodily states. In a ‘sceptical review’ of the literature, Sil-via and Gendolla (2001) have criticised much of the evidence for the perceptual accuracy hypothesis on methodologicalgrounds. They stipulate that a valid test of this hypothesis (with regard to interoception) must compare self-reported inter-nal perception (i.e. counted heartbeats, in our experiment) against an objective standard (i.e. recorded heartbeats), withoutintroducing confounding changes in physiological variables such as heart rate. Our experiment was designed to fulfil theserequirements.

We investigated the effect on interoceptive awareness of two experimental manipulations of self-focus. Using stimuli fre-quently employed in self-focus research (Fejfar & Hoyle, 2000), we contrasted a condition in which participants gazed at aphotograph of their own face (‘the bodily self condition’) with another in which they looked at a set of self-relevant words(‘the narrative self condition’). The baseline (control) condition was looking at a blank screen. Interoceptive awareness wasmeasured using a well-validated heartbeat perception task (Schandry, 1981), which has good test–retest reliability (Muss-gay, Klinkenberg, & Rüddel, 1999; Pollatos, Traut-Mattausch, Schroeder, & Schandry, 2007) and is sensitive to individual dif-ferences (Domschke, Stevens, Pfleiderer, & Gerlach, 2010; Dunn et al., 2010; Ehlers & Breuer, 1992). Gender and change inheart rate were recorded, as these are commonly reported confounds of cardiac awareness tasks (Knapp-Kline & Kline,2005; Ring & Brener, 1992). Our participants were students, to avoid introducing the potential confound of age (Khalsa, Ru-drauf, & Tranel, 2009). It was hypothesised (following the results of Ainley et al., 2012) that interoceptive awareness wouldbe increased by observation of the participant’s own photographed face, given that recognition of one’s face in a mirror andin a still photograph employ similar cortical networks (Butler, Mattingley, Cunnington, & Suddendorf, 2012). Following theperceptual accuracy hypothesis, it was also expected that self-relevant words, which enhance attention to narrative aspectsof the self, would have a similar effect. It was anticipated, as in Ainley et al. (2012), that significant effects would be concen-trated amongst participants who had low interoceptive awareness in the baseline condition.

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2. Methods

2.1. Ethics statement

The study was approved by the Department of Psychology Ethics Committee, Royal Holloway University of London. Allparticipants were volunteers, who gave informed written consent and were free to withdraw at will.

2.2. Participants

Participants were 45 students at Royal Holloway University of London. Four were excluded for artefacts in the heart ratedata. Of the remaining 41 (20 male), the mean age was 21.7 yr (SD = 2.0).

2.3. Stimuli

After obtaining informed consent, a digital photograph (11 cm by 13 cm) was taken of the participant’s face, wearing aneutral expression. This picture was mirror-reversed and used as the stimulus in the bodily self condition. Each participantwas then required to generate 6 self-relevant words, comprising their first name, their hometown, the school they most re-cently attended, their university course, the name of their best friend and the name of the most important person in their life.These words constituted the stimulus in the narrative self condition. They were presented in white font, arranged in a hex-agonal pattern around the centre of a black computer screen, occupying the same area of screen as the self-face photograph.The stimulus for the baseline condition was a black screen with a small white fixation cross (1 cm � 1 cm).

2.4. Procedure

Interoceptive awareness was measured using the Mental Tracking Method (Schandry, 1981), with all stimuli presented ona standard PC. Participants were seated approximately 60 cm from the computer screen and were prompted at the start ofeach trial to keep their eyes on the computer screen while they were counting their heartbeat, during all 9 trials, but theywere not required to fixate on any particular aspect of the stimuli. The room was darkened and the experimenter sat quietly2 m behind, and at 90� to, the participant. After one brief training trial (15 s), there were 9 trials in total, consisting of threetrials in each of the three conditions – baseline, bodily self and narrative self. The total duration of the three trials in eachcondition summed to 105 s, with each individual trial lasting between 20 s and 55 s. Within these constraints, the orderand duration of the 9 trials was fully randomised. At the end of each trial, participants recorded on the computer the numberof heartbeats they had counted. No feedback was given. All instructions were delivered, and behavioural responses recorded,using Presentation software (Neurobehavioral Systems, Albany, CA) on a standard desktop PC. Heartbeat signals were ac-quired with a piezo-electric pulse transducer, fitted to the participant’s left index finger and connected to a physiologicaldata unit (26T PowerLab, AD Instruments), sampling at 1 kHz. This recorded the derived electrical signal onto a secondPC, running LabChart6 software (AD Instruments). Instructions for the Mental Tracking Method (Schandry, 1981) were pre-sented over noise-attenuating headphones. A standard instruction was used (Ehlers, Breuer, & Dohn, 1995) whereby partic-ipants were asked to concentrate hard and try to silently count their own heartbeats, simply by ‘‘listening’’ to their bodies,without taking their pulse. The onset and offset of each heartbeat counting trial were cued by the words ‘‘go’’ and ‘‘stop’’,presented audiovisually.

2.5. Data extraction

LabChart6 was used to identify and count the number of R-wave peaks on the heart trace recorded for each participant, ineach trial, as well as to calculate the average heart rate for each trial (Jennings et al., 1981). Every heart trace was visuallyinspected for artefacts. Where necessary, the number of R-wave peaks was recounted manually. The data from four partic-ipants was excluded because artefacts created uncertainty about the number of recorded beats. Interoceptive awareness (IA)was calculated, for each of the three conditions, by entering the results of the trials for that condition into the formulaIA = {1/3 R [1 � (|recorded heartbeats � counted heartbeats|/recorded heartbeats)]} (Schandry, 1981), where higher scoresindicate higher interoceptive awareness.

3. Results

As in Ainley et al. (2012), we performed a median split of interoceptive awareness (IA) scores in the baseline condition(median = 0.56), to divide the participants into a high-IA (above median) and a low-IA (below median) group. There wereequal numbers of men and women in the two groups.

A repeated measures ANOVA was performed, with experimental condition (baseline, bodily self and narrative self) as thewithin-subjects factor and with both the IA group (high-IA and low-IA) and the participant’s gender as between-subject fac-tors. We checked for gender effects because men are often reported to have higher IA (see Cameron, 2002, p. 149). Bonferroni

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corrections were made for multiple comparisons. Mauchly’s Test of Sphericity was non-significant. The main effect of genderwas non-significant, F(37,1) = 1.04, p = .32, and there was no interaction between gender and experimental condition,F(74,2) = 0.40, p = .68. There was a main effect of experimental condition on interoceptive awareness, F(74, 2) = 5.58,p = .01, g2 = .13 (Fig. 1). Paired sample t tests showed that both the experimental manipulations significantly improved inter-oceptive awareness, compared with the baseline; for the bodily self condition, t(40) = 2.51, p = .02, and for the narrative selfcondition, t(40) = 2.77, p = .01. The difference in interoceptive awareness between the bodily self and the narrative self con-dition was non-significant, t(40) = 0.26, p = .79.

Finally, the interaction of interoceptive group and experimental conditions was non-significant, F(74, 2) = 0.63, p = .54.Thus, overall, the results show that both manipulations of self-focus resulted in improved interoceptive awareness and thatthis improvement was independent of the participant’s baseline IA.

To test whether the effects of the experimental manipulation on interoceptive awareness were influenced by differencesin levels of arousal between the three conditions, we repeated the ANOVA analysis using heart rate as the dependent variable(as a measure of arousal). The three experimental conditions were the within-subjects factor. Both their IA group and par-ticipant’s gender were between-subjects factors. Mauchly’s Test of Sphericity was non-significant. There was no main effectof experimental condition on heart rate, F(74,2) = 2.10, p = .13. The main effect of gender was non-significant, F(37,1) = 0.81,p = .38, and there was no interaction of gender with experimental condition, F(74,2) = 1.61, p = .21. There was no interactionof experimental condition and IA group, F(74,2) = 2.94, p = .06. However, there was a significant main effect of IA group onheart rate, F(37,1) = 6.86, p = .01, g2 = .16, because, as frequently reported in the literature, individuals with low IA generallyhave slower heart rates (Ainley et al., 2012; Cameron, 2001; Fairclough & Goodwin, 2007; Knapp-Kline & Kline, 2005; Ste-vens et al., 2011). This main effect did not interact with the experimental conditions, which therefore rules out the possibilitythat the observed changes in IA can be accounted for by individual differences in average heart rate/arousal. Change in heartrate and change in interoceptive awareness were not correlated, either between the bodily self condition and baseline,r = �.06, p = .70, or between the narrative self condition and the baseline, r = �.16, p = .33.

Because the median in this experiment was relatively low, we also divided the participants into two groups depending onwhether their IA was above or below .66, which was the median reported in Ainley et al. (2012). There was a significant ef-fect of both self-focus conditions only in the group with IA < .66, (n = 28). In this lower-IA group, paired samples t testsshowed that the difference between IA in the self-face and baseline conditions was significant, t(27) = 2.08, p = .045. The dif-ference between IA in the self-relevant words condition and in baseline was also significant t(27) = 2.18, p = .04. In the high-er-IA group (IA > .66) the results were not significant, t(12) = 1.36, p = .20 for self-face versus baseline, nor for self-relevantwords versus baseline, t(12) = 1.64, p = .13. However, the small number of participants (n = 13) in the group with IA > .66 ren-ders these latter figures unreliable.

4. Discussion

We heightened attention to the self, using two manipulations, which have been commonly employed in self-focus re-search. In the bodily self condition participants looked at a photograph of their own face and in the narrative self conditionthey gazed at self-generated, autobiographical words. The effect of these two manipulations on interoceptive awareness wasmeasured with a well-validated heartbeat perception task (Schandry, 1981). Interoceptive awareness was significantly

Fig. 1. Interoceptive awareness in each of the three experimental conditions.

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enhanced in both of the heightened self-awareness conditions, compared to the baseline of looking at a blank screen. Ourfindings extend those of a recent study (Ainley et al., 2012) which showed that mirror self-observation significantly im-proved heartbeat perception, for participants with below-median interoceptive awareness in the baseline. In the currentstudy we have shown that improvement in interoceptive awareness is also elicited by a still self-face photograph, and sim-ilarly by attention to the narrative aspects of the self, such as one’s name or the names of significant others, and that thisincrease is independent of baseline levels of interoceptive awareness. Our experiment adds to converging evidence thatinteroception, which is the perception of sensory signals arising from within the body, interacts with perception of the selfas perceived exteroceptively (Ainley et al., 2012; Maister & Tsakiris, in press; Tsakiris et al., 2011).

Behaviourally, our experiment provides support for the perceptual accuracy hypothesis (Silvia & Gendolla, 2001), whichproposes that any type of enhanced self-focus will improve the accuracy of self-perception. Previous evidence suggestingthat increased self-focus enhances interoceptive accuracy has been marred by methodological issues (Silvia & Gendolla,2001). Reviewing the literature on interoception and self-focus, Silvia and Gendolla pointed out that most published studieshave relied on questionnaire measures of trait self-focus and on self-reported interoceptive sensations. Many have also failedcontrol for arousal (for example using exercise or caffeine as experimental manipulations). This necessarily undermines theconclusions that can be drawn from previous research. Our study, however, was specifically designed to meet these objec-tions by fulfilling the conditions that Silvia and Gendolla (2001) stipulate for an adequate test of the perceptual accuracyhypothesis. They recommended the use of an objective physiological test of interoceptive awareness and required thatchanges in potential confounding variables, such as arousal, should be ruled out. Furthermore, our study uses an experimen-tal manipulation of self-focus, whereas many previous studies have relied on self-report psychometric measures to identifythose who have high trait self-awareness. Silvia and Gendolla (2001) also proposed that consistency seeking could accountfor the result of the flawed studies which have previously been used to support the perceptual accuracy hypothesis. Whenpeople are self-aware, they are motivated to make consistent judgements and to meet task standards. Consistency seeking isparticularly likely where participants are aware of a standard that they are expected to meet. In our experiment there was noapparent standard and no feedback and the task was of similar difficulty in each condition. Consistency seeking would havetended to remove differences in IA across the three experimental conditions and cannot account for the results we report.

Importantly, we show that cues which apparently enhance attention to narrative aspects of the self have equal impact onthe accuracy of interoceptive awareness as those cues, such as one’s own face, which appear to direct attention more spe-cifically to the bodily self. A possible explanation is provided by Damasio’s conceptualisation of the autobiographical self as arepresentation that emerges when the core self (which in his taxonomy is a bodily self) acts upon self-relevant ‘objects’(Damasio, 2010, p. 212), which can include both images and memories. Thus in the current experiment, both our enhancedself-focus conditions provide ‘objects’ on which the core self may act, which could increase the salience of the core self andthus enhance interoceptive awareness.

The mechanism for improved interoceptive awareness during heightened self-focus may be provided by attention-switching activity in the anterior insula. This cortical area is known to be engaged in all interoceptive signalling (see Craig(2009) for a review) including being activated during self-face recognition (Devue & Brédart, 2011). Accuracy in cardiacawareness tasks correlates with both activity and also with grey matter volume in the right anterior insula (Critchley, Wiens,Rotshtein, Ohman, & Dolan, 2004). From converging fMRI and diffusion tensor imaging data, Menon and Uddin (2010) pro-pose that the insula is a hub between brain networks involved in externally-directed attention to stimuli in the environment,and internally-directed attention to cortical midline structures involved in self-refential processes (Northoff et al., 2006), anidea also espoused by Farb, Segal, and Anderson (2012). In our experiment, both the self-focus manipulations may have en-hanced the accuracy of self-perception by shifting attention from the external environment to internal aspects of self-processing.

Previously, interoceptive awareness has been considered a robust trait variable resistant to experimental manipulation(Fairclough & Goodwin, 2007; Khalsa et al., 2008; Stevens et al., 2011). As a result, research into the relationships betweeninteroception and related variables has been correlational rather than causal. It has been impossible, for example, to manip-ulate interoceptive awareness to discover whether anxiety causes, or results from, high interoceptive awareness. Links havealso been demonstrated between low interoceptive awareness and several clinical conditions, such as moderate depressionand negative affect (Critchley et al., 2004; Dunn, Lawrence, & Ogilvie, 2007; Paulus & Stein, 2010; Pollatos, Traut-Mattausch,& Schandry, 2009), psychosomatic disorders (Mussgay et al., 1999), alexithymia, (Herbert, Herbert, & Pollatos, 2011) and an-orexia nervosa (Eshkevari, Rieger, Longo, Haggard, & Treasure, 2011; Pollatos et al., 2008). Given the burgeoning literature onthe emotional, cognitive and behavioural correlates of interoception, our results potentially provide a means to manipulateinteroceptive awareness.

It had been anticipated in the current study that improvements in heartbeat perception during heightened self-focuswould be confined to the below-median interoceptive awareness (IA) group (as in Ainley et al., 2012, where median IAwas .66). In this experiment, however, whether our participants had above and below-median interoceptive awareness madeno significant difference to the effect of the experimental manipulations. This may be explained by the relatively low meanand median interoceptive awareness scores recorded here, which can be attributed to normal sampling variation. Means aslow as .5 (Sutterlin, Schulz, Stumpf, Pauli, & Vogele, 2013) and as high as .84 (Werner, Peres, Duschek, & Schandry, 2010)have previously been reported for the Mental Tracking method. In Ainley et al. (2012), the relatively large (n = 129) and het-erogeneous sample (aged 10–74 yrs) explains why IA in that experiment was close to middle of the published range. Taskinstructions (Ehlers et al., 1995) and experimental paradigm were similar in both studies. Silvia, McCord, and Gendolla

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(2010) found that self-focus and task difficulty interact, such that self-focus boosts performance specifically when a task isdifficult. This might explain why in Ainley et al. (2012) it was the participants with below-median IA who benefited frommirror self-observation, if for them the task was more difficult.

In Ainley et al.’s (2012) experiment the effect of mirror self-observation on interoceptive awareness was open to the po-tential confound that participants might have been using some aspect of their own reflection, such as a visible pulse, to im-prove their heartbeat perception. Here we show that the result does not depend on a living, moving image or on facialexpression, because participants viewed static pictures of their face. Moreover, the changes in IA that we observed cannotbe the result of learning effects or of regression to the mean because the 9 trials were fully randomised, such that a trialin any one experimental condition was followed by another that was likely to be in a different condition.

Enhanced self-focus has been reported to increase arousal (Denson, Creswell, & Granville-Smith, 2012) which, in turn,may improve accuracy in heartbeat perception (Van der Does, Van Dyk, & Spinhoven, 1997). However, this is unlikely to havebeen the cause of the increased interoceptive awareness we observed, because average heart rate did not change signifi-cantly between conditions. Moreover, in neither of the heightened self-focus conditions was the improvement in interocep-tive awareness correlated with resting heart rate or with change in heart rate. Self-focus is known to decrease availableprocessing resources (Panayiotou & Vrana, 2004), so the improvements we observed in heartbeat perception during height-ened self-focus cannot be explained by reduced task demands. The complexity of the stimuli differ between our three con-ditions. In his ‘competition of cues’ hypothesis Pennebaker (1982), argued that additional demands on exteroceptiveperception reduces participants’ ability to concentrate on their interoceptive sensations. It might therefore be expected thatIA would fall in both the enhanced self-focus conditions, which involve more cognitive load than the baseline. Maister andTsakiris (in press), however, have recently shown that looking at a self-photograph raised the interoceptive awareness ofparticipants with below-median IA in the baseline, whereas similar attention to the face of a stranger did not. Their twoexperimental conditions were very similar in cognitive load and processing demands, differing only in self-focus. This rein-forces our conclusions that the changes we detected in our current study depend on increased self-focus rather than differ-ences in stimulus complexity. Moreover, Maister and Tsakiris found no change in IA, between the baseline and stranger’s facecondition, which indicates that differences in complexity of the stimuli cannot account for the changes in IA we observed inthe current experiment.

There are potential limitations to our study. Participants were not screened for anxiety (Domschke et al., 2010) whichmay impact on interoceptive awareness. We did not make allowance for participants’ potential use of time-estimation strat-egies (Dunn et al., 2010), nor for respiratory manoeuvres (Weisz et al., 1988). However, these confounds would apply equallyin each of the three experimental conditions and are therefore unlikely to account for the improvements we observed be-tween the two heightened self-focus conditions and the baseline.

4.1. Conclusion

We successfully increased interoceptive awareness by using two manipulations which have been regularly employed inself-focus research, to heighten attention to the self. These were a photograph of the participant’s face and a set of self-rel-evant words. Both of these enhanced self-focus conditions were equally effective in increasing accuracy in a cardiac aware-ness task. These results show that enhanced attention to the self as perceived exteroceptively (through vision of one’s ownface or self-relevant words) enhances perception of internal interoceptive processes, possible through the gating of attentionin the anterior insula. This experiment demonstrates that aspects of the bodily and narrative self are unlikely to be indepen-dent because enhanced attention to either has similar effects in improving the accuracy of internal perception – a result pre-dicted by the perceptual accuracy hypothesis. This adds to a growing literature indicating that interoceptive andexteroceptive perception interact in forming our sense of our bodily selves. Our study suggests a potential way to experi-mentally manipulate interoceptive awareness, to test for the effects on related aspects of self-processing. These resultsmay have application in improving interoceptive awareness in clinical conditions characterised by low awareness of internalbody states.

Acknowledgments

This study was funded by ERC 2010 StG 262853 and European Platform for Life Sciences, Mind Sciences and Humanities,Volkswagen Foundation (II/85 064) to MT.

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