Abstract
Davidenko and colleagues (Davidenko, Heller, Cheong, & Smith, 2017) reported a new illusion, illusory apparent motion (IAM), in which randomly refreshing (1-3Hz) pixel arrays can elicit percepts of globally coherent motion moving in any number of directions (diagonal, rotating, etc.). In a recent study, we found that even with the many possibilities for disambiguating IAM, participants can mentally control their motion percepts (Allen, Jacobs, Panda, Carroll, Spears, Chen, & Davidenko, 2019) as has been shown in simpler ambiguous motion stimuli before (e.g., Kohler, Haddad, Singer, & Muckli, 2008). This finding led to two questions: (1) Is the ability to mentally control one’s percepts consistent across different ambiguous motion stimuli? and (2) Is it harder for participants to mentally control IAM compared to apparent motion quartets (AMQ), given that IAM affords many possible interpretations? To address these questions, the current study compared mental control of ambiguous motion across four different stimuli: IAM, AMQ, a structure-from-motion cylinder, and a rotating Necker cube. Participants first completed a baseline block where they continuously reported the direction of motion they perceived during 30-second trials of each of the four stimuli. Then, participants completed a second block where they were instructed to mentally hold a specified motion direction or change between two motion directions as quickly as possible. Results comparing average “change times” across 30 participants showed a correlation between IAM and the SFM cylinder. Average “hold times” showed correlations between IAM and AMQ, IAM and the SFM cylinder, and AMQ and the SFM cylinder. In addition, average times for IAM and AMQ were very similar across both hold and change trials. These results suggest that mental control in IAM shares common mechanisms with other ambiguous motion stimuli despite the added complexity of IAM stimuli.