We're trying to create a database of users that we can contact for our future UX needs. But the pool is small and specialized (doctors). Can you offer any advice for how to encourage sign-up from a pool of people who may not be motivated by money?
Well if it is not money (which usually works), then it has to be a cause they care about or a promise to improve their user experience. I've heard many complaints from doctors and pharmacists working at hospitals having bad experiences with the software they use and the way the whole process of documenting their work flows.
In addition to that, I recommend keeping the money option offered but in different forms if cash is not working. By knowing more about users, you could find out what would work better for them ... Think about providing the money in forms like trips, subscriptions, discounts, gift cards...etc.
Just an example from personal experiences, some people would much prefer A Visa gift card than paper cash. Although the card is mainly cash in a card but it feels different...
How about offering the incentive money as a donation to a charity or cause of their choice?
Specialized professionals are the hardest to recruit since they have no time even if you offer to compensate them. Might also be a conflict of interest if they receive compensation in the case of doctors. If your user group is interested in giving feedback on the user experience but have no time for lab testing, you could offer to schedule sessions at their workplace (if possible) or remotely and after work hours.
I also find that keeping the pool engaged by keeping them updated of features/changes that were implemented as a result of their feedback and testing, really works. People like to be involved and see the results of their contributions. Too often, in UX research, we forget or don't have time to share our findings with participants.
Side note: Participants who aren't receiving compensation tend to give better feedback and are more motivated to complete tasks (or try to complete them) compared to paid participants.
... how to encourage sign-up...
- Many users (including physicians and pharmacists) would gladly participate in usability studies if it would improve the software they use, as Mo'ath notes.
You can organize testing at times and locations that are convenient to subjects, as Ling suggests. For instance, many hospitals have educational lunch seminars.
Doctors may simply not know that you are seeking participants for usability studies. How are you reaching out to them?
Consider involving residents. They haven't yet bought into any particular system, so they tend to be more interested in their future options.
Demonstrating that feedback is taken seriously by making real changes would also be helpful, as Ling notes.
You can gather data with surveys and opt-in metrics. Include sign-up for usability studies with your surveys.
... who may not be motivated by money?
I would leave money out of it. If you want to give to charity, that's fine, just keep it separate – Do not let your left hand know what your right hand is doing. Doctors can be motivated by money, just like anyone else, but there are social and legal factors that make monetary incentives problematic. Reporting requirements. Conflicts of interest. Even just providing free pens is frowned upon. It's simply easier to stay away from the controversy.
Also, as Ling states:
Participants who aren't receiving compensation tend to give better feedback and are more motivated to complete tasks (or try to complete them) compared to paid participants.