Experimental task
The participants completed two sessions of the word association
learning task described in the general methods, using an MRIcompatible
button box to make their responses on each trial. Both sessions
were completed inside the MRI scanner.Motivational manipulation
While inside the scanner, the participants used a button box to rate
their task motivation on a sliding scale from 0 to 10. Next, the experimenter
prompted the participants verbally to state at least two reasons
why they gave the rating they did, rather than a lower number. The results
of experiment 1 suggested that a manipulation like this one increased
motivation and task performance for some participants, and
further indicated that individual differences in the extent of the elicited
motivation changes were correlated with changes in task performance.
Focusing on individual differences in the effects of the motivational
interviewing manipulation allowed us to explore the relationship between
changing motivation, feedback processing, and task performance
in a sample that included participants whose motivation increased as
well as those whose motivation remained stable or decreased over time.