The touch of a harpsichord is very different from a piano - first there is a little resistance as the slip of quill pushes up the string, then suddenly *ping* it gives way. All but the most heavily voiced instruments will have a light touch and take less effort to produce fast runs and trills than a piano demands, but they sound muddy very quickly unless played with well-defined articulation. Because there is practically no dynamic range, the way you bring across the idea of loud or soft is through the articulation - and where it matters almost more how you depress keys on the piano to get expressiveness, on the harpsichord the more important thing is how you lift off again. Your adjudicator would indeed have been giving you a compliment on some well-executed staccato, I think

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I have heard many pianists try to play harpsichords and not manage to get that one right: I also know several keyboard players, including my husband and YAP, who can play either equally well. I think it needs sensitivity to do it, and a brute-force pianist is less likely to manage to transfer their skills to a harpsichord, but I'd have thought that if anything, trying out the plucked keyboard instruments would give pianists some idea of how they might tackle earlier music and bring out more of what it contains - and to answer the question, no, I can't see how it could possibly affect piano technique in a negative way.