What Physiological Changes and Cerebral Traces Tell Us about Adhesion to Fiction During Theater-Watching?

Abstract

Live theater is typically designed to alter the state of mind of the audience. Indeed, the perceptual inputs issuing from a live theatrical performance are intended to represent something else, and the actions, emphasized by the writing and staging, are the key prompting the adhesion of viewers to fiction, i.e., their belief that it is real. This phenomenon raises the issue of the cognitive processes governing access to a fictional reality during live theater and of their cerebral underpinnings. To get insight into the physiological substrates of adhesion we recreated the peculiar context of watching live drama in a functional magnetic resonance imaging (fMRI) experiment, with simultaneous recording of heart activity. The instants of adhesion were defined as the co-occurrence of theatrical events determined a priori by the stage director and the spectators' offline reports of moments when fiction acted as reality. These data served to specify, for each spectator, individual fMRI time-series, used in a random-effect group analysis to define the pattern of brain response to theatrical events. The changes in this pattern related to subjects' adhesion to fiction, were investigated using a region of interest analysis. The results showed that adhesion to theatrical events correlated with increased activity in the left BA47 and posterior superior temporal sulcus, together with a decrease in dynamic heart rate variability, leading us to discuss the hypothesis of subtle changes in the subjects' state of awareness, enabling them to mentally dissociate physical and mental (drama-viewing) experiences, to account for the phenomenon of adhesion to dramatic fiction.

Keywords: dynamic HRV; fMRI; fiction; human communication; narrative processing; state of consciousness; theater.

Figure 1

Brain areas (in red) with significant BOLD signal differences when contrasting periods of the play with and without theatrical events. The activated clusters are significant at p < 0.0001, corrected (cf. Table 1). Correlation analyses between the subjective events in agreement with theatrical events (assumed to reflect adhesion to the theatrical reality) and the mean signal changes (in arbitrary units) were computed for each subject in the six regions of interest circumscribed by black circles. Encapsulated figures: A significant positive correlation between activation in response to theatrical events and the adhesion rate was only found in the left anterior IFG for subjective responses related to both text- and direction-related markers, and in the left pSTS for subjective responses related to direction markers. The co-ordinates in brackets are those of the ROI center.

Figure 2

Forty-second excerpts of Poincaré plots depicting, in three participants, the dynamic HRV response associated to the occurrence of a theatrical (T) and/or a subjective (S) event. The upper line refers to the individual fMRI time-series alternating baseline periods (green) with an active period (red) time-locked to the initial theatrical event (T). The successive Poincaré plots were computed in 30-s windows by plotting each R-R interval against the previous one. The sequence was obtained by sliding each 30-s window by 5-s shifts, synchronized with every other fMRI repetition time (TR = 2.5 s) and with the subject's timesheet reports. The successive plots present distinctive patterns as a function of the rRR value. The points spread out further along the diagonal in plots outside the active period, while they cluster together within the active period. The R-R autocorrelation coefficient (rRR), i.e., the correlation coefficient between R-R(n) and R-R(n + 1), was worked out in each window. The decrease in rRR denotes predominant vagal influence (Otzenberger et al., 1998). The brackets refer to statistical inferences, computed on rRR prior to and at the onset of events of interest [i.e., initial theatrical events and all subjective events (S)].