As IRBs review participant incentives for studies, they assess whether the incentives are coercive or exploitive. New research provides a snapshot of the diversity of these incentive offerings, revealing monetary payments for biomedical studies tend to be 10 times higher than payments for sociobehavioral studies.

Investigators performed a retrospective review of IRB-approved studies, including 100 sociobehavioral studies and 32 biomedical protocols. They found 74% of the biomedical studies offered payment, compared to 55% of sociobehavioral studies. Biomedical study payments ranged from zero to $2,880, with an average of $136. Sociobehavioral studies ranged from was zero to $225, with an average of $15.90. (More information is available at:

“We had a relationship with the IRB locally, where they allowed me to review all their confidential materials [and removed identifiers],” says Brandon Brown, PhD, MPH, associate professor of medicine with the Center for Healthy Communities, at the University of California, Riverside School of Medicine. “At my university, I sit on the IRB, and sometimes questions on payments come up in studies. Every IRB is different, but one reason we did the study is there is not a lot of information on payments in research.”

What Is Considered Coercive?

Payments to participants should not be so high that they are considered coercive. But no one knows how to identify what type of pressure is too much. “The goal was to find out more about how we can make payment decisions,” Brown says.

Factors typically related to participant payments include the number of study visits required, if any, and how much time is required. The level of risk also matters.

“Is it low risk or high risk, and what is the research method — quantitative, or something mostly qualitative?” Brown asks. “All of these factors make a difference in determining which payment amounts are provided in research.”

Investigators explored how decisions on participant payments compared with study risk. For instance, most biomedical studies would be considered higher risk than most sociobehavioral studies. “We looked at biomedical studies that should be higher risk, and we found payment for biomedical studies was significantly higher on average, and also in general,” Brown says.

Studies may use different sorts of incentives, but the study compared only cash payments.

IRBs may ask researchers questions about participant payments that appear to be expensive, but a bigger issue involves exploitation. “If you have a well-functioning IRB, people are less worried about coercion than exploitation of participants,” he says. “Are they doing a study and not being properly compensated for their time?”

Be Aware of Potential Exploitation

Exploitation is an issue when researchers ask people to spend time on a study that provides no personal benefit, and the participants are not compensated for their time. For example, researchers studying social determinants of health might want to connect with people with lower incomes and limited access to healthcare. These potential participants might work full-time jobs that leave them little leisure time. If researchers ask participants to take time out of their lives to answer survey questions or to sit in a focus group, they should be compensated for that time, Brown says.

“If we just want to ask them questions that take an hour of their time, it’s important for us, as researchers, to keep in mind that everyone’s time is valuable and important,” he says. “We should make sure they don’t lose out financially by participating in our study.”

Biomedical clinical trials also could be exploitive. “People may have to drive somewhere and take time off from work,” Brown says. “We need to be aware of how we are exploiting people in research, especially in how we do this in clinical trials, including some that are abroad.”

People in foreign nations who are participating in a clinical trial of a pharmaceutical developed by a U.S. company might not receive benefits of the research until many years later. “We reap the benefits here in the United States before others do, so exploitation is on top of the minds of ethicists in some research,” he says.

From the IRB’s perspective, payments to participants cannot be considered as a benefit in the study’s risk-benefit calculation. “But, surely, for participants themselves, payment is a benefit of participating in research,” Brown says. “This is why we have incentives; otherwise, we would not get as many people participating in research if we didn’t offer something. This is why we can have exploitation.”

Brown and co-investigators plan to study incentive payments in research, including comparing the perceptions of payment among different groups. “We can imagine participants might view payment differently than researchers, and they may think about payment differently than IRB members,” Brown says. “But the real questions we have are how does payment impact participation in research, and how do we determine appropriate amount of payment in research?”

No one knows how people determine a particular payment amount for a study. “What we’re going to do is talk to these different groups and establish a paradigm for all future clinical research and try to come up with a consensus on what should be considered in choosing payment amounts,” he explains. “Finally, at the end of the study, we’ll create some hypothetical study scenarios and ask the groups to tell us what they think about whether a payment amount is appropriate and what would be proposed as a payment for that study and why. We can’t justify what payment is too high or too low without having data.”