For detecting spammers and bots, we advise you use Captcha (we use reCAPTCHA) in your screeners. To do this, select "Captcha" from the "Add element" button.

This will add the question to the screener, and present the participant with a Captcha confirmation during the screener process. If the participant fails the Captcha, they will be disqualified from the remainder of the screener. Additionally, you can add a prompt to the Captcha.