EXPRESS: The influence of prime-related trial-wise visibility measures on masked response priming

Masked priming paradigms have been widely used to investigate the processing of nonconscious visual stimuli. Few studies have considered that trial-by-trial assessments of prime visibility turn masked priming paradigms into dual-tasking situations. In our study, we conducted two experiments using metacontrast to investigate how different subjective and objective visibility measures influence masked response priming under single- and dual-task conditions. Both experiments revealed larger priming effects in the dual-task than in the single-task conditions, supporting the notion that the prime-related response draws attention to the prime, thereby enhancing its processing and the resulting priming effects. Experiment 1 further showed that response times were faster and priming effects larger for bimanual than for unimanual responses. Differences between subjective and objective visibility measures were observed in Experiment 1, but not confirmed in Experiment 2. Furthermore, varying the task relevance of the prime arrow's direction by employing specific instructions either highlighting arrow direction or non-directional prime features failed to produce any significant differences in priming effects. Taken together, our results show that trial-by-trial assessments of prime visibility in a metacontrast masking paradigm can enhance priming effects and suggest that the choice of visibility measure plays a minimal role, as the existence of a trial-wise visibility measures matters more than its format.