I am not entirely sure that I understand your numbers. We had 12 donors in the old age group and 16 in the young and middle age, respectively. Each of these donated two pads. These pads where subsequently cut into 4 pieces, each. That renders a total of 128 individual pieces for each age group but the old that had 96. To prevent influence of any one individual, we created so-called "super-donor stimuli" that consisted of four pieces from four separate individuals (from the same age group). Care was taken to avoid repeatedly including the same individuals within the same stimulus. Moreover, in all analyses, any variance that could be explained by the rated intensity was removed (covariates). One could argue that we had a sampling error where a few individuals still managed to influence the outcome. However, if you take a look at the Supplementary Figure 1, you can see the actual ratings of all stimuli. If sampling luck would be a valid concern, clear sporadic “bumps” would be evident. As can be seen in this figure, one such “bump” exists. However, post-hoc tests for statistical outliers did not classify these stimuli (or any other) as statistical outliers. Taken together, I agree that sampling error is, and should always be, a great concern in any study. Nevertheless, we went to a great length to reduce this risk and our post-hoc statistical analyses suggest that our measures were successful in eliminating this risk.