I am analysing the outcomes of a pilot project involving people' reaction (reaches and engagements) to posts related to plastic pollution. To enhance engagement we proposed "challenges" i.e. contributions in terms of pictures, ideas exchange, etc., with awards, related to our specific posts.

Apparently we caught a group of serial participants to giveaways, who usually enroll in all kinds of social media activities which can bring them an award.

I am not specialist of the topic, but I wonder if there is a) a definition or keywords for the phenomenon and b) literature in this respect, so to be able to describe the phenomenon and the eventual bias in our data.

Thank you for your help