The Heartfelt Self: Investigating Interactions between Individual Differences in Interoceptive Accuracy and Aspects of Self-Processing

Recent models of the self accord a key role to ‘interoception’, defined as afferent information arising within the body affecting the behaviour, emotion and cognition of the organism, with or without awareness. The purpose of this thesis was to investigate how individual differences in awareness of internal bodily signals (‘interoceptive accuracy’ (IA), measured by heartbeat perception) relate to two key aspects of self-processing. The first three experiments considered awareness of the self from an exteroceptive perspective, while the second three investigated awareness of the processing of action. Experiments 1 and 2 manipulated IA by enhanced attention to the self. In people for whom IA was initially low, heartbeat perception was improved by self-observation in a mirror, as well as by gazing at a self-photograph and at self-relevant words. Experiment 3 found a significant negative correlation, in women, between self-objectification and IA. Experiment 4 investigated the relationship between IA and the ‘social Simon effect’. No significant effects were found. Experiment 5 found that people with high IA were significantly less able to inhibit imitation during ‘automatic imitation’, potentially because they are more empathetic and thus prone to imitate. Experiment 6 investigated the relation between IA and agency, using time-awareness paradigms pioneered by Libet et al. (1983) and Haggard et al. (2002). A positive correlation was found between IA and ‘intentional binding’, indicating that people with high IA have a stronger sense of agency. The result depended entirely on ‘effect binding’. Replicating recent reports, effect binding was correlated with the amplitude of the early readiness potential in the operant sound condition and also with sensory attenuation. However, IA was not linked to either of these variables. Taken together, the findings reported here provide support for a model of interoceptive accuracy within a predictive coding framework, which is presented in the Discussion.