Koko itself has not undergone formal research evaluation, however, it is based on a web-based platform, Panoply, which was evaluated in a general population. Initial evaluations of Panoply found benefits in reductions of depressive symptoms as well reductions in perseverative thinking and increases in cognitive appraisal which were the intended targets for the cognitive restructuring activities underlying Panoply (Morris, Schueller, & Picard, 2015).
Morris, R. R., Schueller, S. M., & Picard, R. W. (2015). Efficacy of a web-based, peer-to-peer cognitive reappraisal platform: A randomized controlled trial. Journal of Medical Internet Research, 17, e72.
“The Panoply platform produced significant improvements from pre to post for depression (P=.001), reappraisal (P<.001), and perseverative thinking (P<.001). The expressive writing platform yielded significant pre to post improvements for depression (P=.02) and perseverative thinking (P<.001), but not reappraisal (P=.45).”