Poster D82, Monday, March 27, 8:00 – 10:00 am, Pacific Concourse
Multivoxel pattern analysis reveals task-general representation of decision criterion
Benjamin Turner1, Evan Layher1, Nicole Marinsek1, Puneeth Chakravarthula1, Anjali Dixit1, Amir Meghdadi1, Barry Giesbrecht1, Miguel Eckstein1, Michael Miller1; 1University of California, Santa Barbara
A common model of recognition memory holds that when humans make “old”/“new” judgments, they compare the item’s mnemonic signal against a criterion before deciding whether to endorse the item as “old.” In the fMRI literature, a standard contrast -- between studied items correctly identified as “old” versus unstudied items correctly identified as “new” -- is commonly understood to reflect mnemonic processes. However, our lab has shown that in a widespread frontoparietal network, criterion placement plays a major role (Aminoff et al., 2015). In a new study, we scanned 30 participants while they performed memory and perception tasks. Participants were induced to shift their criteria across blocks of trials with a payoff manipulation, while deciding on each trial whether the item had been studied (memory task) or contained a human (perception task). We carried out two classification analyses in each of two a priori-defined frontal and parietal ROIs. First, separately for each trial type and task, we classified items according to which criterion condition (liberal or conservative) each item appeared in. Second, separately for each trial type, we classified across tasks by training the criterion discrimination using only memory data and testing using only perception data. We highlight two results: 1) within-task classification successfully predicts a conservative or liberal trial regardless of the item type, including old or new items; and 2) surprisingly, memory data accurately predicts perception data. These results extend our previous results, suggesting that these ROIs are agnostic to the type of evidence and instead represent decision-making processes.
Topic Area: LONG-TERM MEMORY: Episodic