From 2019... The neuroscience of Romeo and Juliet: an fMRI study of acting

From 2019... The neuroscience of Romeo and Juliet: an fMRI study of acting. Steven Brown, Peter Cockett and Ye Yuan. Royal Society Open Science, March 13 2019. https://doi.org/10.1098/rsos.181908

Abstract: The current study represents a first attempt at examining the neural basis of dramatic acting. While all people play multiple roles in daily life—for example, ‘spouse' or ‘employee'—these roles are all facets of the ‘self' and thus of the first-person (1P) perspective. Compared to such everyday role playing, actors are required to portray other people and to adopt their gestures, emotions and behaviours. Consequently, actors must think and behave not as themselves but as the characters they are pretending to be. In other words, they have to assume a ‘fictional first-person' (Fic1P) perspective. In this functional MRI study, we sought to identify brain regions preferentially activated when actors adopt a Fic1P perspective during dramatic role playing. In the scanner, university-trained actors responded to a series of hypothetical questions from either their own 1P perspective or from that of Romeo (male participants) or Juliet (female participants) from Shakespeare's drama. Compared to responding as oneself, responding in character produced global reductions in brain activity and, particularly, deactivations in the cortical midline network of the frontal lobe, including the dorsomedial and ventromedial prefrontal cortices. Thus, portraying a character through acting seems to be a deactivation-driven process, perhaps representing a ‘loss of self'.

4. Discussion

Despite the central importance of role playing in both everyday social interactions and the theatrical arts, it has been little studied in either the psychology or neuroscience literatures. We sought to address this neglect by carrying out the first neuroimaging study of dramatic role playing, employing trained actors as participants. Because of the wide diversity of actor-training methods, we opted to work with a uniform population of actors, all of whom had a similar training in the dominant form of acting in North America and who possessed a similar amount of training and performance experience. In addition, because MRI experiments are so restrictive of body movement and facial gesturing, we chose to examine a group of actors specialized in the mentalistic approach to character portrayal most commonly taught in theatre schools.

The imaging results showed that acting led to deactivations in brain areas involved in self processing, with a focus on the dmPFC/SFG and vmPFC. This might suggest that acting, as neurocognitive phenomenon, is a suppression of self processing. The major increase in activation associated with role change was seen in the posterior part of the precuneus. Perhaps the most surprising finding of the study was that the British accent condition—during which the participants were instructed to maintain their self-identity—showed a similar deactivation pattern vis-à-vis the self that acting did, suggesting that gestural mimicry of even a completely unspecified other has an impact on brain areas involved in self processing. This supports the contention of acting theorists that gestural and psychological approaches might be related paths towards achieving the same goal, namely the embodied portrayal of a character [8,51,60]. It also lends support to theories of embodied cognition, which argue that a change in gestural expression can influence the way that people think and the emotions that they feel [61,62].

We are aware of only a single prior study that attempted anything like our Fic1P condition, that of Ames et al. [47], although their task was not intended as an acting condition per se. While our vmPFC deactivations were quite a bit dorsal to theirs, we found a similar increase in deactivation for Fic1P compared to 1P, as well as for 3P compared to 1P. The British accent showed a comparable deactivation in the vmPFC to the 3P condition (when both were compared with 1P), but less than that for acting. However, the most acting-specific deactivation we observed was not in the vmPFC but in the dmPFC/SFG. In addition, we observed an area of activation increase in the precuneus that was specific to acting compared to the other three conditions, although it emerged through the loss of deactivation compared to 1P. We would like to consider these findings in terms of the two processes of perspective change and role change.

4.1. Perspective change

One of the major objectives of the study was to compare the pattern of brain activation for acting with that for the well-studied process of 3P perspective taking, referred to as ToM processing. In several respects, our study was biased towards seeing an overlap between acting and mentalizing. First, the participant population consisted of actors with a mentalistic orientation towards getting into character that emphasizes inferring the thoughts, emotions and motivations of a character in a given situation. Second, our scanner task required participants to engage in the psychological process of formulating responses to hypothetical questions. It is perhaps not surprising that answering questions as Romeo or Juliet would tap not only into role playing but mentalizing as well in order for the participant to determine an appropriate answer from the perspective of the character. In other words, an actor would have to consult some degree of third-person knowledge about Romeo or Juliet—just as with any person other than the self—in order to formulate answers from their perspective. So, neural similarities between Fic1P and 3P may be more of a reflection of our question-answering task than of the nature of acting, since acting theorists believe that mentalizing about a character is far more important during the preparatory phase of studying a role than during the process of character portrayal in performance [7].

With respect to our ToM contrast, the most significant difference between 3P and 1P was a deactivation in the vmPFC and the ventral part of the dmPFC, which became the major marker of perspective change in this study. This same deactivation was seen more intensely in the contrast of acting to 1P. In both cases, the effect resulted from a decrease in the level of activation compared to the self condition. Hence, the presence of the vmPFC deactivation for acting might indicate that actors engage in 3P perspective-taking with their character while undergoing the process of acting, or that acting is a more intense form of perspective taking, since there was a greater reduction in vmPFC and dmPFC-v activities for Fic1P than for 3P. This interpretation is only reasonable if this process occurs in an implicit manner. This would also account for the same, but weaker, deactivation effect seen in the British accent condition. While participants in the 3P condition were told to explicitly assume the perspective of their close other, this was not the case during either the acting or accent conditions. If anything, during the accent condition, participants were clearly instructed not to stray from the self perspective. Hence, if an increasing deactivation in the vmPFC and dmPFC-v is a marker of deviation from the self perspective, then this would have to work during both explicit tasks (like 3P and other types of ToM tasks) and implicit tasks where people psychologically stray from the self perspective, but in which they are not told to assume another person's perspective. Van Overwalle & Vandekerckhove [63] reviewed both electroencephalography and fMRI evidence suggesting that implicit mentalizing employs the same mentalizing network as explicit mentalizing. If anything, the medial PFC has been shown to be more strongly linked with implicit than explicit mentalizing [64]. Similar results were obtained when comparing implicit and explicit forms of trait judgement [65].

4.2. Role change

Acting produced additional effects beyond the ones in the vmPFC and ventral dmPFC that were observed in the 3P condition, suggesting that acting is something more than just mentalizing about a character. One of these effects was a deactivation in the dmPFC/SFG for acting versus self that was also observed in British accent versus self, while the other was an activation increase in the precuneus that was found when acting was contrasted with either self (1P) or other (3P).

dmPFC and SFG. A large dorsoventral extent of the dmPFC was shown to be deactivated during acting when compared to the 1P condition, compatible with the loss of a self-related process during acting and gestural pretence. Denny et al.'s [26] meta-analysis of self/other processing argued for a dorsoventral distinction in the medial PFC such that the vmPFC showed an overlap between self and other processing (when each one was compared against a low-level baseline), while the dmPFC showed a preference for other compared to self processing. Our results seem incompatible with those findings, since we observed the highest level of dmPFC activity in the self condition, and less in each of the other conditions. Therefore, we would like to consider another dimension of self processing that may be tracked in our results.

D'Argembeau et al. [48] carried out a study of trait judgements about the self, but did so across the mental time frames of ‘present self' and ‘past self', as well as ‘present other' and ‘past other'. A peak in the dmPFC at MNI coordinate −2, 56, 26 (compared to Talairach coordinate −6, 50, 28 in Fic1P versus 1P) showed greater activity for the present self than the other three conditions. In addition, another dmPFC peak at MNI coordinate 4, 46, 44 (compared to Talairach coordinate −3, 38, 37 in Fic1P versus 1P) showed an interaction effect such that it was more active for the present self than the other three conditions. D'Argembeau et al. [66] followed up on these findings and showed that the dmPFC's preference for the present self extends beyond the past self to include the future self as well. Van der Cruyssen et al. [67] showed that both of the regions just mentioned were more active when people processed information about social categories of people (e.g. ambulance driver, kindergarten teacher) than simply adjectival trait descriptions (e.g. attentive, picky). Consistent with these studies on trait judgements about the self and others, the activation likelihood estimation (ALE) meta-analysis of Schurz et al. [28] showed that a dmPFC peak at Talairach coordinate 6, 26, 55 (compared to Talairach coordinate −12, 29, 55 in Fic1P versus 1P) is more active when people perform trait judgements than when they do false-belief mentalizing tasks. Likewise, Benoit et al. [68] found that the more ventral parts of the dmPFC have a preference for self over other trait-judgements, and Ma et al. [65] showed that the more dorsal part of the dmPFC is more active during spontaneous compared to intentional trait judgements. Garrison et al. [69] carried out a study in which participants were asked to make judgements about adjectives in terms of the self (Does the word describe you? Yes or no). The results of this task showed strong activations throughout the dorsoventral extent of the dmPFC. By contrast, several parts of the dmPFC were deactivated (when contrasted with rest) during a mindfulness meditation condition in the same participants, perhaps suggesting a reduction in the embodied self through meditation. Therefore, the dmPFC might encode more-enduring and stable features of the self, rather than a person's current mental states, the latter of which are examined in ToM tasks. If so, then the deactivations seen in the dmPFC for acting would represent a loss of self processing related to a trait-based conception of the self.

One possible interpretation of our results is that parts of the dmPFC encode information about not just an awareness of the self (with regard to both traits and states) but perhaps a sense of embodiment of the self. The embodied self can be considered as a zero-sum entity due to resource limitations. A person has only one voice, one face and one body as personal traits. The more that someone portrays another person, the fewer the resources there are to devote to him/herself. One cannot speak with a British accent and Canadian accent at the same time. Therefore, acting might be akin to a deliberate process of possession, i.e. a substitution of the actor's self by the character due to their embodiment of the character. The results of the British accent condition in our experiment suggest that even when a character is not being explicitly portrayed, gestural changes through personal mimicry can be a first step towards the embodiment of a character and the retraction of the self's resources. Certain entertainers, such as ventriloquists, rapidly switch between the self and a character within the time frame of a dialogue. It would be interesting to explore what is occurring in their brains as they make these rapid but seamless transitions between self and character.

Precuneus. The precuneus emerged as the major area of activation increase during role change in this study (along with a weak effect seen in the pSTS/TPJ). Activation was seen here for acting when it was compared against each of the three other conditions, although the activation itself resulted from a loss of deactivation compared to those conditions. The medial parietal cortex has been well established as a component of both the mentalizing network and the default mode network (DMN) [58], and emerges as a consensus region of activation in virtually all of the meta-analyses of the ToM literature that have been published [25–31]. However, before we interpret our acting effect as a mentalizing process, it is important to note that our precuneus activation is 20–30 mm posterior to the standard peaks found for ToM tasks. A typical y coordinate for ToM analyses is in the −50 to −60 range, whereas our peaks were in the −70 to −80 region. Hence, this establishes a distinction between the PCC (anteriorly) and precuneus (posteriorly), where mentalizing activations tend to be overwhelmingly in the PCC. Likewise, in keeping with the role of the PCC in the DMN, the PCC was strongly deactivated in all four of the conditions in this study when contrasted with fixation (see figure 1 for the 1P results). This preferential activation of the PCC during the resting state is the typical pattern for components of the DMN [56]. However, this region did not appear in any of the high-level contrasts, suggesting that the level of deactivation of the PCC was comparable across all of the task conditions and was therefore unaffected by either perspective change or role change. Only the precuneus, but not the PCC, showed a difference when acting was compared against the other three conditions.

Regardless of whether the relative increase in activation for the precuneus for acting was due to an increase in activation or a decrease in deactivation (as was in fact the case), the question we have to address is what processes activate the precuneus. We would like to consider two literatures where the precuneus is implicated. One is attention. The precuneus is a component of the dorsal attentional network of the brain, a network that is involved in functions such as attentional orienting, episodic retrieval and mental imagery [70–72]. It is telling to point out that acting theorists for over a century have talked about the ‘split consciousness' involved in the process of acting [4,8,10]. The actor has to be himself and someone else at the same time, and this could lead to a splitting of attentional resources devoted to the focalization of attention and consciousness. This is not simply the ‘divided attention' of multi-tasking procedures, but a fundamental split of resources devoted to a maintenance of one's identity as a conscious self. According to this interpretation, activation of the precuneus would represent a dispersion of self-related attentional resources, whereas deactivation would represent a focalization or internalization of such resources. If so, then deactivation should occur during situations like mindfulness meditation, where self-related attentional resources are focalized. Garrison et al. [69] conducted a study in which a combined group of experienced meditators and non-meditators performed three types of mindfulness meditation in the MRI scanner (i.e. concentration, loving kindness and choiceless answers). The baseline condition was rest. The results showed that the precuneus (in addition to the PCC) was strongly deactivated during meditation, in the same region as our Fic1P versus 1P contrast. In fact, deactivations in the posterior precuneus have been reported in a number of studies of meditation [73–75]. The question for our purposes is why the precuneus effect was mainly seen for acting and not for the 3P and accent conditions. All we can say is that neither gestural modification in the form of a foreign accent nor other-orientation in the form of 3P mentalizing had an influence on this neural mechanism, whereas the explicit psychological process of role change through character portrayal did, perhaps resulting in the double consciousness that acting theorists talk about. Again, acting was the only condition in which self-identity was explicitly split during the task. Further research will be required to explore these findings.

4.3. Impersonation

In an interesting study of vocal impressions, McGettigan et al. [76] had participants perform the opening lines of familiar nursery rhymes either (i) in their normal voice, (ii) while impersonating other individuals (such as celebrities or family members) or (iii) while putting on a foreign accent. While the study was more oriented towards sensorimotor aspects of vocal performance than towards role playing or acting, the study is one of the few to address the issue of impersonation. Their impersonation versus accent contrast is in some respects quite similar to our acting versus accent contrast, although their use of familiar texts creates a difference from our improvisational question-answering task. In other words, their task is closer to an act of pure mimicry than an attempt to portray a complex character the way our actors did. The contrast of impersonation versus accent revealed activations in the pSTS, anterior STS, superior temporal gyrus and PCC. The only point of commonality with our results is their activation in the left pSTS at MNI coordinate −45, −60, 15, compared to our activation in the right TPJ for Fic1P versus Accent at Talairach coordinate 42, −61, 22 (table 2). The authors argued that activations in the pSTS and temporoparietal region might reflect the fact that ‘the emulation of specific voice identities…requires accessing the semantic knowledge of individuals' [76, p. 1882]. Beyond semantics, the pSTS has a strong connection with the perception and production of emotional expression, including not only vocal prosody but also facial expression and body gesturing [77–80]. Hence, the pSTS activation for impersonation in McGettigan et al. [76] and for acting in our study might reflect something about resources related to expressiveness in prosodic production.

5. Limitations

The present study is the first of its kind, and so it will be important for other studies to replicate the findings reported here, not least given the complex patterns of activation and deactivation that were observed. While we attempted to use a uniform group of trained actors, there are many approaches to getting into character, and so other types of actors—most especially gesture-based actors—should be analysed in future studies. In addition, we used experienced amateurs rather than professionals as our participants. It would be interesting to carry out a follow-up study with professional actors, although this would undoubtedly lead to variability in the training and performance experience of the participants, compared to the more uniform population analysed in the present study. The results with our British accent condition suggest that even small gestural manipulations, such a change in the manner of speaking, can lead to neural differences similar to full-fledged character portrayal. Outside of the domain of professional acting, there has been an explosion of interest in role-playing video games [3,81–83], and neuroimaging studies have begun to look at brain activations in gamers perceiving avatars of themselves and others while in the scanner [84]. Gamers could be yet another type of non-professional population to explore in examining neural processes of role change.

Because of our desire to compare acting with self processing and ToM, we used an improvisational question-answering task during the acting condition, rather than having the actors recite rehearsed monologues. Importantly, improvisational methods are central to the training of actors, not least the actors used in the present study. The hot-seating technique that is commonly used in rehearsal for character development follows a question-and-answer format comparable to ToM studies, with the exception that the actors are expected to answer the questions in the 1P as their characters. The participants were familiar with hot-seating technique, which was used to help them develop an attachment to their characters during the workshop phase of this study (see Methods). They were therefore familiar and comfortable with responding to hypothetical questions while in character as Romeo or Juliet. However, we cannot rule out the possibility that some of the results may be due to the fact that the actors were more personally familiar with their answers in the 1P and 3P conditions, whereas they had to ‘make up' answers in the Fic1P condition. A future study could look at the production of rehearsed dramatic monologues compared with the production of pre-learned passages generated about self-experiences (i.e. rehearsed self-monologues). Overall, future studies need to explore (i) various types of participant populations (professional actors of different training backgrounds, gamers, ventriloquists, etc.) and (ii) different types of acting tasks (rehearsed versus improvised).