I'm not aware of any formal studies, if you mean that. The easy example I usually use is asking you, as a human, to fold a paper into 10 equal pieces without any tools to assist you in measurement; then try folding into 16 equal pieces. This demonstrates that even though you have (presumably) grown up with decimal, you can still work better with tonal in practice. If you don't want to waste 2 papers, http://www.intuitor.com/hex/switch.html has a Java applet demonstrating the same in software (but for hexadecimal, which shares this same benefit as tonal).