Here they are at VoxEU on how to motivate effort:
The task for the subjects is to alternately press the “a” and “b” buttons on their keyboards as quickly as possible for ten minutes. The 18 treatments attempt to motivate participant effort using i) standard incentives; ii) non-monetary psychological inducements; and iii) behavioural factors such as present-bias, reference dependence, and social preferences. Figure 1 presents, in somewhat shortened format, the phrasing of the 18 treatments and the average effort (number of button presses) per treatment.
Via the fantastic Development Impact blog.