Volunteer-Based Online Studies With Older Adults and People with Disabilities.

There are few large-scale empirical studies with people with disabilities or older adults, mainly because recruiting partici­pants with specific characteristics is even harder than recruit­ing young and/or non-disabled populations. Analyzing four online experiments on LabintheWild with a total of 355,656 participants, we show that volunteer-based online experiments that provide personalized feedback attract large numbers of participants with diverse disabilities and ages and allow ro­bust studies with these populations that replicate and extend the findings of prior laboratory studies. To find out what mo­tivates people with disabilities to take part, we additionally analyzed participants' feedback and forum entries that discuss LabintheWild experiments. The results show that participants use the studies to diagnose themselves, compare their abilities to others, quantify potential impairments, self-experiment, and share their own stories -- findings that we use to inform design guidelines for online experiment platforms that adequately support and engage people with disabilities.