Wednesday, February 15, 2017

Damned if you do, damned if you don't

Here's a common puzzle that comes up all the time in discussions of replication in psychology. I call it the stimulus adaptation puzzle. Someone is doing an experiment with a population and they use a stimulus that they created to induce a psychological state of interest in that particular population. You would like to do a direct replication of their study, but you don't have access to that population. You have two options: 1) use the original stimulus with your population, or 2) create a new stimulus designed to induce the same psychological state in your population.

One example of this pattern comes from RPP, the study of 100 independent replications of psychology studies from 2008. Nosek and E. Gilbert blogged about one particular replication, in which the original study was run with Israelis and used as part of its cover story a description of a leave from a job, with one reason for the leave being military service. The replicators were faced with the choice of using the military service cover story in the US where their participants (UVA undergrads) mostly wouldn't have the same experience, or modifying to create a more population-suitable cover story. Their replication failed. D. Gilbert et al. then responded that the UVA modification, a leave due to a honeymoon, was probably responsible for the difference in findings. Leaving aside the other questions raised by the critique (which we responded to), let's think about the general stimulus adaptation issue.

If you use the original stimulus with a new population, it may be inappropriate or incongruous. So a failure to elicit the same effect is explicable that way. On the other hand, if you use a new stimulus, perhaps it is unmatched in some way and fails to elicit the intended state as well. In other words, in terms of cultural adaptation of stimuli for replication, you're damned if you do and damned if you don't. How do we address this issue?