Seriously participated? Including catch trials does not in itself improve the assessment of explicit sense of agency in online experiments

Abstract

The explicit sense of agency (SoA) is usually assessed using rating tasks. However, it is challenging to minimize non-serious participants. To address this, we investigated whether including catch trials could itself influence the effect of action–outcome delays on explicit SoA in an online experiment. Participants were randomly assigned to no-catch, catch with alert, or catch without alert groups. They rated SoA by a circle appearing after the fixation disappeared following a 200–1,000 ms delay following a keypress. Without the fixation (i.e., the catch trials), the circle suddenly appeared without a keypress in the catch with alert and catch without alert groups. The participants were either informed in advance or not about the catch trials. A reliable action–outcome delay effect was observed in all groups, and found to be the least in the catch without alert group. These results suggest explicit SoA could be measured accurately in online experiments without catch trials, whose inclusion did not improve SoA measurement. We concluded that catch trials in online experiments should be combined with information.