# Leader-Follower Role Allocation for Physical Collaboration in Human Dyads
## 4 Discussion
Due to this, we could state that when applied in real-life situations any metric used in this study can be used to define the higher-performing or lower-performing individual and which metric is used should be decided based upon its accessibility rather than its SEM. However, to solidify this statement a larger scale study should be performed to observe whether the differences in results between the metrics increase or decrease on a larger set of examples. _Determining the leader-follower dynamics:_ As stated previously, the results of this study showed that the subject with higher performance in the individual tasks is most likely to be the leader in a collaborative setting, which agrees with our hypothesis. This might occur due to the subjects not needing to change their actions much between the individual and collaborative tasks. In other words, when coupled together both subjects will use approximately the same amount of force as in the individual trials, meaning that the subject exerting a larger amount of force in the individual task will exert a larger amount of force in the collaborative task as well, thus assuming the role of the leader. This explanation can be further supported by the findings in [15], where they found that subjects perform collaborative tasks based on pre-programmed motion plans, regardless of their partner. What is interesting, however, is that ANOVA analysis showed that there is a statistically significant increase in the leading partner's influence on movement when the size and distance of the target increases, indicating that the leader-follower roles are proportional, rather than being confined to pure leadership. This might be related to the fact that reaching targets that are located closer to the starting point requires less aiming to successfully perform the task and are more based on subjects' reaction times. However, the correlation between the size of the target and the influence of the leading partner on the overall task manifests as the leader having a greater influence when the size of the target is larger. Knowing both these factors we could hypothesise that the leading individual has the greatest influence on the task performance between the starting section and finishing section of the path, while when reacting and aiming, actions are mutually influenced by both partners. This indicates that the leader-follower roles are not consistent throughout the task, but rather interchange dynamically as was also proposed and demonstrated for human-robot collaboration in [23; 24]. Here, both studies showed that dynamic exchange of roles improves task performance, however in [24] the study reported that subjective acceptance in participants has decreased when leader-follower roles were exchanged dynamically. Due to this, in future work leader-follower role distribution in human dyads should be further explored by analysing the tasks in segments to better understand how they occur naturally. Determining task performanceThe results of task performance seen in Figure 5 correlate to the discoveries presented in [18], where the results showed that the task performance of both subjects improves in collaborative tasks, while subjects performing a task with a lower-performing partner improve less than subjects performing the same task with a higher-performing partner. This can be expected as in collaboration the forces applied to the controlled point equal to the sum of forces from both individuals; meaning, when both subjects exert approximately the same amount of force in a collaborative task as they did in individual tasks, the force for each subject would increase by the force of their partner, when comparing the individual and collaborative task separately. This in turn leads to shorter task times and better task performance. Statistical analysis also showed that the task performance is significantly influenced by the size and distance of the target.