If enabled on your system, you may be asked to take an online prescreen before you use the system. Depending on how the prescreen is configured, you may have the option to opt out of the entire prescreen and/or individual questions. You should realize that declining to participate in the prescreen or certain questions may affect your eligibility for some studies, so participation is encouraged.

In some cases, you may earn credit for participating in the prescreen, and you may even earn credit if you decline to participate in the prescreen. If either case holds true, the system will inform you of this before you commence the prescreen.

The prescreen may consist of multiple sections. All questions are either multiple-choice or fill-in (free-entry) answer. At the end of the prescreen, you may have a chance to review and change any of your responses. After you save all of your responses, you may not participate in the prescreen again (unless the administrator has allowed this or deleted your existing responses), so answer all questions carefully.