In all experiments, there can never be a fixed answer to music. Much work on aesthetics is of a highly subjective nature, and it is quite common for scientists and psychologists alike to confuse empirical fact with pure opinion. Sometimes, criticisms tend to be emotional and opinionated rather than scientific, especially if the scientist himself has his own prejudices about what music is. Data and graphs may be slightly modified to suit their opinions. There will always be exceptions to the rule.
All experiments have their own shortcomings.
Technical errors may occur. The understudy could be lying or has his own prejudices, is influenced by the environment and times that he is living in, or many other exceptions and reasons that might influence the outcome of the experiment. Test materials used in experiments can sometimes be an issue of conflict. It should be apparent that the use of musical materials in tests which are not simply measures of attainment presents certain problems. Once the decision to use musical material has been made, it is difficult not to be biased in favour of music of a particular type.