I don’t know about anyone else; under time pressure I personally would go about looking for ‘one wrong argument in a sea of high-quality arguments’ very differently than I would go about looking for ‘one misleading but superficially high-quality argument in a sea of high-quality arguments’ or ‘one very-high-quality argument in a sea of high-quality arguments’.
Did your description to the participants state that the arguments were high-quality?
I can look up the exact wording if it’s helpful, but I assume it’s clear from the basic setup that at least one of the arguments has to be misleading.
I don’t know about anyone else; under time pressure I personally would go about looking for ‘one wrong argument in a sea of high-quality arguments’ very differently than I would go about looking for ‘one misleading but superficially high-quality argument in a sea of high-quality arguments’ or ‘one very-high-quality argument in a sea of high-quality arguments’.