I am really interested in Bayesian analysis, but I don't get the issue of sampling intention being so important in frequentist t-tests; if you have 60 values you have 60 values surely - why does your intention matter? The computer does not know what I intended to do; or have I missed the point entirely!?
That is exactly the point -- intuitively (for natural Bayesians) the stopping and testing intentions should not matter (for some things), but for p values the stopping and testing intention is of the essence, sine qua non. In lieu of reading the BEST article, see this video, starting at 7:15 minutes:
One other quick question if I may; how does the BEST package differ from the BayesFactor package?
An appendix of the BEST article explains, but you can instead see this video, starting at 2:35 minutes:
Those video excerpts might make the most sense if you just start with the first and watch them through, all the way...