When participants take part in online research they get repeatedly exposed to research materials. This can lead to the problem of 'nonnaïveté', which has been identified as one key challenge for experimental online research. Chandler et al. (2015) have found that nonnaïveté can reduce effect sizes and undermine statistical power.
Starting today, you can filter Prolific participants based on the number of studies they have previously completed. You can now recruit people that have done, say, less than 10 studies before. Of course, you can specify any number of previous studies you like.
If you're looking for experienced rather than naïve participants, then you can also set the minimum number of studies a participant has to have completed – no problem!
This new prescreening criterion is called "Number of previous submissions" and you can find it, as usual, in the prescreening tab (step 3) in your dashboard:
This is our first step in addressing the problem of nonnaïveté. Our new feature cannot guarantee that participants are 100% naïve because they might still be exposed to certain methods or measures elsewhere (e.g., in their universities, on other platforms). In the long run, we'll need to work out how to deal with nonnaïveté more generally, not just within Prolific. If you have any ideas or suggestions to this end, comment below or shoot us an email: firstname.lastname@example.org!