Please do (one of) the following:
- Run Inquisit Lab on that Mac and check what Tools -> Keyboard Scancodes... returns for the attached keyboard's ESC key.
- Run a test script with a <trial> set to accept any response and check the response column for the value returned when you press the ESC key.
(AFAIK, ESC may map to scan code 53 on Macs.)
I have specified the ESC key as the quit command for my Inquisit script (scan code 1 as indicated in the Inquisit online help). This works fine on a PC, but not on a Mac, at least when launched from Safari. Is there a different set of mappings that need to be considered?
<defaults>/ quitcommand = (1)</defaults>