This thesis reports a series of studies investigating the relationship between empathy and the mirror neuron system through the observation of simple actions that are devoid of emotion. Prior research has suggested that such a relationship exists, but also has hinted that it is more complex due to the different types of empathy that may exist. Specifically, this thesis examines cognitive (perspective taking) and emotional (the emotional response) empathy and their link to the execution and observation of simple actions in the absence of emotional effectors. It provides original contributions to knowledge with a new proposal of how empathy may drive the mirror neuron system and the mentalizing system (two theoretical neural networks) to interact, and a proposal that equally high levels of cognitive and emotional empathy may cause cognitive strain. It also provides the first investigation of the neural processes of the two-person social inhibition of return task (a task investigating the delay in returning to a location previously visited by oneself or another individual), and delves into the issue of state empathy (an aroused emotional reaction to perception of another’s state) superseding trait empathy (the inherent ability to experience empathy).
After an introduction in Chapter 1 to the main areas of interest relevant to the thesis, Chapter 2 reports an experiment that investigated the relationship between cognitive empathy and simple motor activity. EEG activity was recorded over the motor area while participants observed and performed simple actions demonstrated by a model. Analyses revealed significant suppression in mu/alpha (8-12 Hz) and beta (18-22 Hz) EEG bands, indicative of sensorimotor activity, during both observed and executed actions. Crucially, participants rating higher in perspective taking as a measure of trait cognitive empathy showed significantly less beta suppression when observing actions. The direction of this relationship, contrary to studies involving induced emotional empathy, may reflect individual differences in mentalizing and mirroring mechanisms to understand others’ actions. I suggest that at the unconscious level it is primarily the mirror neuron system that controls such automatic behaviour, regardless of how great the capacity an individual’s cognitive empathy may be. In contrast, when it comes to deliberate, controlled actions, it appears that greater cognitive effort is required and the mentalizing system plays a greater role.
Chapter 3 followed up a key question that arose from Chapter 2: Could I demonstrate the cognitive difference in employing the mirror versus the mentalizing systems? Based on the results reported in Chapter 2, because those higher in perspective taking hypothetically employ greater cognitive efforts than those lower in the trait, they would be well practiced in using more cognition. Therefore, due to the extra effort required in an initial cognitive task, those lower in perspective taking would be expected to show more cognitive impairment in a subsequent cognitively demanding task. The two studies reported in this chapter did not satisfactorily resolve this question. The attempt to manipulate state empathy through similarity, however, produced an interesting interaction between perspective taking and empathic concern. As expected, when participants felt similar to the woman in the first task’s videos and had low emotional empathy, those high in cognitive empathy performed better in the second task--a Stroop task--than those low in cognitive empathy. However, this pattern was reversed for participants high in emotional empathy with those low in cognitive empathy outperforming those high in the trait. These results suggest that the higher level of emotional empathy, possibly enhanced by the similarity condition, conflicts with and overrides the influence of cognitive empathy and that perhaps people work optimally with either dominant emotional empathy or dominant cognitive empathy, but less so with high or low levels of both.
Chapter 4 investigated further a second question raised by the study in Chapter 2: Would the results be affected by interaction with a second person? This study involved recording event-related potentials while two participants executed and observed simple actions together. The task used was a coordinated button pressing task measuring an effect known as inhibition of return (IOR). Results were consistent with other studies in demonstrating the IOR effect, behaviourally and neurally. Empathy was found to moderate some relationships in the fronto-central P2 and parietal P3 ERP components. Interactions in the P2 component showed that those low in empathic concern had less activity when they were currently executing a trial and had previously observed a trial. The unusual situation between the two participants created by the strange setup with the EEG caps appeared to enhance levels of state empathy for each other. One would expect that those naturally higher in emotional trait empathy would feel this to a greater extent, thus increasing their focus on the other person’s turns, compared to those lower in the trait. The other finding for empathy indicated that those lower in perspective taking had less activity in the P3 component when the previous trial had been observed compared to executed, whereas there was no difference for those higher in perspective taking. I attributed this to the diminished amount of empathy with the other person in those with lower cognitive empathy, thus rendering them less affected by the other’s actions and more interested in their own.
With some novel new findings, the studies in this thesis have demonstrated the complexity of empathy as it relates to the brain and behaviour for the execution and observation of simple actions in the absence of emotional effectors.