## 6 Discussion and Implications  
RQ1: To what extent does a contrasting auditory stimulus affect user performance when synchronizing with controls?  
From a psychological point of view, selective attention works quite well, since users are generally able to concentrate on visual rhythm, ignoring interfering auditory stimuli. In fact, no performances differences were found between Sound and Mute conditions for any gender and age range (see Figure 5), so we can state that the presence of interfering stimuli during interaction with the system should not affect users' performance. However, the results of the questionnaire showed that--at least female--participants thought it was easier to synchronize in the Mute condition (see Figure 6). This, on second thought, would seem reasonable considering that the auditory stimulus, even if it does not really affect users' performance, is in any case a disturbance.  
As an implication, it could be said that rhythmic interaction techniques can be used without major concern for background music (for example, while watching television or listening to music) or noise in the environment. In fact, even if a possible auditory stimulus could be considered a disturbance, the effects on the synchronization capacity--at least with regard to rhythmic interference--are practically nonexistent.  
With regard to the participants' comments, 12 of them stated that their performance was not affected by the drum loop, and considering that their activation times and error rates were indeed very similar, we can state that their comments reflect the reality of the data. Concerning the other six participants who stated that the drum loop negatively affected their performance, we can state that this was only a subjective feeling, considering that their comment is not reflected in the data. The averages of these participants indicate that there was a negligible difference of 200 ms in the activation time between the conditions in favor of the Mute condition. In terms of errors, they were even less in the Sound condition, and this further confirms that it was a subjective feeling that did not reflect the reality of the data.  
RQ2: To what extent do age and gender affect user performance when synchronizing with controls?  
Regarding age and genders, our results are in line with previous works, (e.g., [14; 15]), which demonstrated that reflex skills vary considerably depending on the age and gender of the users. In fact, we can generally state that activation time and error rate increase with age, and females perform worse than males--at least as far as younger users are concerned.  
Particularly, we have enough data to state that males perform better than females in terms of error rate, at least in the 18-40 age range, considering both Sound and Mute conditions. Finally, in terms of activation time, we have enough data to state that males performs better than females, at least in the 18-25 age range.  
Accordingly, age and gender differences clearly have implications for the design of rhythmic interaction techniques. Generally, previous studies showed that a slower rhythm speed facilitate synchronization, i.e., users make less errors. Previous studies (e.g., [1; 2; 3]) focused on finding the best compromise between lower activation times and error rate, showing that errors decrease at lower speed of rhythm. Therefore, we may assume that slower rhythms speeds can be employed to facilitate the synchronization of less capable users. We then suggest that rhythmic interaction techniques include a brief configuration phase in which the ideal rhythmic speed for the end user is determined in a guided manner for example, using a wizard. Broadly speaking, age and gender does not really matter if we look only at the individual skills of the users. What really matters is that users feel comfortable with the given rhythm speed, considering that the optimal speed may vary considerably from individual to individual.