## 2 Materials and Methods
### Analysis
#### 2.5.1 Main Analyses
Similar to the case of Q1 through Q4, a 99.0% CI that did not include zero would indicate that participants perceived the two trials significantly different (\(p<0.01\)). Furthermore, the average (i.e., mean[(count(two trials perceived differently)-count(two trials perceived the same)]) \(>0.0\) at 99.0% CI would indicate that a significantly (i.e., \(p<0.01\)) larger proportion of participants did not perceive the two trials were carried out using the same underlying robot-arm motion control. Additionally, we considered the ratio of each individual's preference between (sham) human- versus robot-controlled trials. For this purpose, we first computed each individual's (sham) human-controlled and robot-controlled ratios as \(\frac{number\ of\ times\ (sham)human-controlled\ selected}{total\ number\ of\ responses}\) and \(\frac{number\ of\ times\ robot-controlled\ selected}{total\ number\ of\ responses}\), respectively. For each of these ratios (i.e., separately), we then calculated its bootstrapped (10,000 simulation runs) average response at 99.0% CI (i.e., random sampling with replacement). We considered the following null hypothesis. **Hypothesis 5 (H5). **: _Participants' preference for (sham) human-/robot-controlled trial was at chance level._  
We tested Hypothesis 5 against the following alternative hypothesis. **Hypothesis 6 (H6). **: _Participants' preference for (sham) human-/robot-controlled trial significantly differed from chance level._  
In the case of these tests, the 99.0% CI that did not include 0.5 would indicate a significant difference from chance at \(p<0.01\). Furthermore, participants' preference would be significantly above chance if the average preference associated with 99.0% CI \(>0.5\). Last, we examined the effect of (sham) human- and robot-controlled trials on participants' physiological responses by analyzing the change in the cortisol level in their saliva samples. For this purpose, we first subtracted the participants' cortisol levels that were sampled prior to their trials (one per robot- and (sham) human-controlled trials) from their cortisol levels that were sampled immediately after their trials were finished. We then performed Lilliefors test with Monte Carlo approximation (95.0% CI or equivalently \(p<0.05\) significant level) to determine whether participants' cortisol data followed a normal distribution. This test did not reject the hypothesis that the change in participants' cortisol levels was normally distributed (\(p=0.2837\), kstats = 0.09, critical value = 0.11). Therefore, we applied a parametric three-factor (participants' gender \(\times\) (sham) operator's gender \(\times\) trials' order) ANOVA. This test indicated non-significant effects of participants' gender, operator's gender, and their interactions (with one another as well as with respect to trail's order). Given these observations, we discarded the participants' gender and formed two sets of change in cortisol level: one that comprised all participants' robot-controlled trial and the other that corresponded to their (sham) human-controlled trial. We then performed a two-sample t-test on these two sets.