1. A method comprising: selecting at least two participants from a plurality of participants and grouping the at least two participants; presenting a first image to the at least two selected participants; receiving from each of the at least two selected participants, a content-identifying term for said first image; determining, via a computer system, if the content-identifying term received from the at least two selected participants match; and responsive to determining that the content-identifying terms match and that the matching content-identifying terms are not included in a list of forbidden terms, storing the matching content-identifying term as a label for the first image, and adding the matching content-identifying term to the list of forbidden terms.