Are we becoming glued to our phones through clever, addictive designs? Technology critics and industry defectors argue that smartphones are compelling more and more of our attention, drawing us away from meaningful relationships and focusing us on unhealthy thoughts and behaviors. Yet researchers continue to find that smartphones, videogames, and social media are beneficial or harmless on average.

How do we make sense of these conflicting claims? How can we discover the impacts in our own lives, whatever might be true on average? And how might those discoveries contribute back to science and policy?

when researchers study average treatment effects with between-subjects tests, their findings often exclude consideration of minority and marginalized groups

In 2018, CAT Lab organized the Gray Phone Challenge, a pilot community/citizen science endeavor to find out if turning mobile phones grayscale had any impact at all on people’s screen time. Using our software platform Conjecture, people could sign up at any time and be guided through the process of conducing their own experiment about phone addiction.

Conjecture is software that supports n-of-one trials, experiments that people conduct in their own lives. Unlike between-subjects studies (like clinical trials) that provide an average effect across a group of people, Conjecture generates personalized knowledge about the impact of technology in the lives of each person involved.

N-of-one trials enable community scientists to test concerns in their own lives with the full rigor of experiments.

N-of-one trials, otherwise known as single-case experiments, were formalized by statistician Lancelot Hogben as a counterpoint to what he called a “tyranny of averages” introduced by the eugenicist RA Fisher. Hogben observed that when researchers study average treatment effects in between-subjects experiments, their findings can exclude consideration of individuals or minority groups. Research on the social and behavioral impacts of technologies face the same problem; technologies that are benign or even beneficial on average can still cause considerable harm at the margins. That’s where N-of-one trials might help, since they enable community scientists to test concerns in their own lives with the full rigor of experiments.

What did our participant-investigators find? You can read the results of the pilot study in the pre-print below. Having successfully completed this initial study, we’re actively looking for high-value questions that matter in people’s lives for future investigation. So please contact us with your ideas!

Steps in the Gray Phone Challenge: 1: take survey, 2: install moment app, 3: one week all color, 4: email us weekly data, 5: four-week challenge, 6: receive results.


  • In April 2022, our academic paper about Conjecture was accepted for publication by the ACM Conference on Fairness, Accountability, and Transparency, the leading peer-reviewed venue for this kind of research in computer science.


Study Materials