The purpose of this study is to develop and test the utility of a smartphone program, mPhenomic, that facilitates peer recruitment via SMS text messages and assess how different behavioral incentives affect this system. Outcomes are measured by the number of referrals that participants, called seeds, make to people, named leads, in their social networks. The key eligibility criteria are recent participation in a research study that is also actively recruiting and the ownership of an Android or Apple smartphone/tablet that has access to the internet and SMS text function. Subjects will be randomized to receive one of four types of behavioral incentives (control, social good, micropayment compensation, lump sum compensation). Arm 1 will have no behavioral incentives and will serve as the control arm. Arm 2, the social good arm, will receive personalized verbal and visual encouragement by research staff. Arm 3 will receive $10 per referral for up to 5 referrals paid in micropayments. Arm 4 will receive $10 per referral for up to 5 referrals paid in a lump sum at the completion of the two-week intervention phase. We aim to include 25 subjects in each arm, with participants who make 5 or more referrals having the option to repeat the referral process up to two more times. Prior to making any referrals, surveys will be administered to the seeds to assess their social networks and level of engagement with and/or acceptance of mobile device technology in their everyday lives. After each referral is made, seeds and their referred leads will be asked to answer a few questions about the referral interaction. The study will take a minimum of two weeks or a maximum of six weeks (for qualifying seeds).

You may be eligible for this study if you meet the following criteria:

• Conditions: behavioral
• Age: 99 years or below
• Gender: All