Conducting online visual psychophysics experiments: A replication assessment of two face processing studies

In vision sciences, researchers rigorously control the testing environment and the physical properties of stimuli, making it challenging to conduct visual perception experiments online. However, online research offers key advantages, including access to larger and more diverse participant samples, helping to address the problem of underpowered studies and to enhance the generalizability of results. In face recognition research, increasing diversity is essential, especially considering evidence that cultural and geographical factors influence basic visual face processing. The present study tested a new online platform, Pack & Go from VPixx Technologies, that supports experiments written in MATLAB and Python. Two face recognition experiments based on a data-driven psychophysical method involving real-time stimulus manipulation and relying on functions from the Psychtoolbox were tested. In Experiment 1, the visual information used for face recognition was compared across four conditions that gradually reduced experimental control over the testing environment and stimulus properties. In Experiment 2, the association between face recognition abilities and information utilization was measured online and compared to lab-based results. In both experiments, results obtained in the lab and online were highly similar, demonstrating the potential of online research for vision science.