Elsevier

Consciousness and Cognition

Volume 25, April 2014, Pages 42-50
Consciousness and Cognition

Being watched: The effect of social self-focus on interoceptive and exteroceptive somatosensory perception

https://doi.org/10.1016/j.concog.2014.01.010Get rights and content

Highlights

  • How does social self-focus affect interoceptive and exteroceptive somatosensory processing?

  • Self-focus manipulated via a video camera.

  • Use of Somatic Signal Detection Task (SSDT) and heartbeat counting.

  • Exteroceptive, but not interoceptive, somatosensory sensitivity higher during self-focus.

  • Interoceptive sensitivity positively correlated with SSDT false alarm rates.

Abstract

We become aware of our bodies interoceptively, by processing signals arising from within the body, and exteroceptively, by processing signals arising on or outside the body. Recent research highlights the importance of the interaction of exteroceptive and interoceptive signals in modulating bodily self-consciousness. The current study investigated the effect of social self-focus, manipulated via a video camera that was facing the participants and that was either switched on or off, on interoceptive sensitivity (using a heartbeat perception task) and on tactile perception (using the Somatic Signal Detection Task (SSDT)). The results indicated a significant effect of self-focus on SSDT performance, but not on interoception. SSDT performance was not moderated by interoceptive sensitivity, although interoceptive sensitivity scores were positively correlated with false alarms, independently of self-focus. Together with previous research, our results suggest that self-focus may exert different effects on body perception depending on its mode (private versus social). While interoception has been previously shown to be enhanced by private self-focus, the current study failed to find an effect of social self-focus on interoceptive sensitivity, instead demonstrating that social self-focus improves exteroceptive somatosensory processing.

Introduction

Considerable research evidence supports the multi-level model of body perception and body awareness (Berlucchi & Aglioti, 2010). In order for us to be aware of, and have an accurate perception of our bodies we must co-perceive various sensory inputs, including interoceptive, exteroceptive, proprioceptive, vestibular, tactile, and visual signals (Neisser, 1993). For a large part, we become aware of our bodies interoceptively, by processing signals arising from within the body (e.g., heart beats, respiration, gastrointestinal functions), and exteroceptively by processing signals arising on (e.g., touch), or outside the body (e.g., vision). While research on multisensory integration delineates how exteroceptive signals are combined and then impact body-awareness (e.g., vision and touch, or vision and audition; see Tsakiris, 2010 for a review), little is known about the integration of signals across interoceptive and exteroceptive somatosensory modalities. Even though interoceptive and exteroceptive signals are processed separately in the brain (e.g., Farb et al., 2013, Hurliman et al., 2005) the two modes of bodily perception are highly interconnected (Simmons et al., 2012) and need to be integrated to bring about body awareness (Craig, 2009). Recent empirical investigations demonstrate that combined interoceptive-exteroceptive signals can significantly alter ownership of a virtual hand (Suzuki, Garfinkel, Critchley, & Seth, 2013), as well as awareness of one’s body in space (Aspell et al., 2013), providing behavioral evidence to suggest that interoceptive and exteroceptive signals are integrated to jointly shape body awareness and perception.

As body perception ultimately relies on the online integration of sensory signals across different modalities—a dynamic process strongly modulated by attention (e.g., Talsma & Woldorff, 2005)—state-dependent fluctuations in both interoceptive and exteroceptive somatosensory perception as a function of varying modes and degrees of attention to the self could be expected. Distinct modes of self-focus enhance aspects of the self directly related to the given focus-mode—for example, mirrors have been found to elicit a more private self-focus, by directing individuals’ attention to inner aspects of the self, whereas video cameras have been found to elicit a more social self-focus by drawing individuals’ attention to the external, observable to others aspects of the self (Carver and Scheier, 1981, Davies, 2005). Private self-focus has been found to enhance interoceptive sensitivity, as reflected by higher heartbeat perception accuracy when attending to pictures of self, self-referential words (Ainley, Maister, Brokfeld, Farmer, & Tsakiris, 2013) or reflection of self in a mirror (Ainley et al., 2012, Weisz et al., 1988). The way in which private self-focus affects exteroceptive somatosensory perception is less clear than in the case of interoception. A recent study by Mirams, Poliakoff, Brown, and Lloyd (2013) shows that body-scan meditation practice, in which participants are trained to attend to selective areas of the body one at a time while taking the time to notice any somatic sensations in a non-evaluative manner, is followed by an increase in sensitivity and decrease in false alarm rates on a tactile perception task, suggesting enhanced tactile perception following the meditation practice. The authors point out that their results contradict the findings from their previous study (Mirams, Poliakoff, Brown, & Lloyd, 2012) examining the effects of interoceptive versus exteroceptive attention on somatosensory processing, which found that interoceptive attention increases an individual’s propensity to report feeling a tactile stimulus regardless of whether it has occurred or not. They conclude that bodily self-focus might have differential effects on somatosensory processing depending on the mode of attention (localized, non-mindful interoceptive attention versus generalized, mindful body-scan meditation). Consequently, further research is necessary to delineate the way in which self-focus affects interoceptive and exteroceptive somatosensory processing.

While several studies have investigated effects of various modes of private self-focus on body perception, no study to date has examined how processing of bodily signals, both interoceptive and exteroceptive in nature, is affected by social self-focus. Social self-focus has been successfully elicited in experimental settings with a turned on video camera facing the participant as if s/he is being filmed (e.g., Burgio et al., 1986, Duval and Lalwani, 1999). As there is evidence that private self-focus and social self-focus can have distinct cognitive effects (Davies, 2005), it is possible that social self-focus might impact body awareness in a different manner than private self-focus. The aim of the present study was to investigate whether social self-focus evoked by a turned on video camera (self-focus condition: camera turned on and facing the participant; non self-focus condition: camera turned off and facing away from the participant) would affect interoceptive and/or exteroceptive somatosensory processing.

We assessed interoceptive somatosensory processing by measuring cardiac interoceptive sensitivity (IS), which is commonly quantified as an individual’s heartbeat perception accuracy score, calculated by comparing the number of heartbeats the individual reports to the number of heartbeats that actually occurred in a given time interval, with better heart beat perception accuracy reflecting higher interoceptive sensitivity (Schandry, 1981). In order to measure exteroceptive somatosensory processing we used a modified Somatic Signal Detection Task (SSDT; Lloyd, Mason, Brown, & Poliakoff, 2008). The SSDT involves detecting the presence of a near-threshold tactile stimulus presented on 50% of the trials, while a simultaneous visual stimulus, such as an LED, also flashes on 50% of the trials, resulting in an increase in participants’ hit rate and false alarm rate due to the flashing LED (Lloyd et al., 2008). A signal detection analysis is used to establish whether any observed change in responses is due to an effect of the manipulation on tactile sensitivity (i.e., ability to tell apart signal from noise), response criterion (i.e., propensity to report feeling a tactile stimulus), or both. Overall, higher sensitivity, higher hit rate, and lower false alarm rate suggest higher exteroceptive/tactile awareness of the body. We hypothesized that the self-focus condition would be associated with enhanced somatosensory processing. We predicted that the self-focus condition would bring about an increase in interoceptive sensitivity as reflected by better heartbeat perception accuracy in the “camera on” as opposed to “camera off” condition. We further hypothesized that the “camera on” condition would be associated with improved tactile perception and that this would be reflected by increased sensitivity on the SSDT, driven by increased hit rate and decreased false alarm rate in the “camera on” as opposed to the “camera off” condition. As significant differences in emotional and cognitive processing based on individuals’ interoceptive sensitivity level have been found—for example, in regards to emotional experience (e.g., Pollatos, Herbert, Matthias, & Schandry, 2007), decision-making (e.g., Werner, Jung, Duschek, & Schandry, 2009), and memory performance (e.g., Werner, Peres, Duschek, & Schandry, 2010)—we have also aimed to investigate potential modulation of SSDT performance by IS level. We expected individuals with higher IS to display more accurate tactile perception, as reflected by higher sensitivity, higher hit rate, and lower false alarm rate. Lastly, we also wanted to examine whether the effect of social self-focus on interoceptive and/or exteroceptive somatosensory processing would be moderated by IS level.

Section snippets

Participants

Fifty-seven (48 female; Mean age = 18.67 years; SD = .93 years) undergraduate psychology students at Royal Holloway, University of London took part in the experiment in compensation for course credit.

Experimental design

The experiment was a fully counterbalanced within-subject design. Participants completed the interoceptive sensitivity (IS) task and the Somatic Signal Detection Task (SSDT) two times each—one time with the video camera turned on and facing the participant (i.e., social self-focus condition), and one

Association between IS and Somatic Signal Detection Task performance

Interoceptive sensitivity scores (across all participants) were correlated with SSDT outcome variables of hit rate, false alarm rate, sensitivity, and response criterion for the non-self-focus condition. As IS scores in this condition were not normally distributed, Spearman’s ρ correlation coefficients were computed. IS scores were positively correlated with overall false alarms in the camera off condition (ρ = .299, p = .024), which was driven by the significant positive association between IS and

Discussion

The current study investigated interoceptive and exteroceptive somatosory perception under two conditions: self-focus and non-self-focus, as manipulated with a video camera being turned on or turned off, respectively. Contrary to our predictions, interoceptive somatosensation, as measured with a heartbeat perception accuracy task, was not significantly affected by the self-focus manipulation. However, exteroceptive somatosensation, measured with the Somatic Signal Detection Task (SSDT),

Conclusions

To conclude, we investigated the effects of social self-focus on exteroceptive somatosensory processing, as measured with the Somatic Signal Detection Task, and interoceptive sensitivity, as measured with a heartbeat perception accuracy task. Our results show that when a video camera was turned on, it enhanced tactile perception, but did not affect heartbeat perception accuracy, relative to the “camera off” condition. Essentially, it can be concluded that social self-focus, as manipulated with

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