Many studies of unconscious processing measure priming effects. Such experiments test whether a prime stimulus can exert an effect on speeded responses to a subsequently presented target stimulus even when participants are unaware of the prime. In some studies, participants are required to report their awareness of the prime in each trial - a dual-task design. Other studies conduct such visibility tests in separate experiments, so that the priming effect is measured via a single task. Both these approaches have pros and cons; however, it remains unclear to what extent they can affect the process of interest. Can the choice of experimental design and its parameters interfere with the priming effect? This could have implications for interpreting such effects, including in previous literature.

 

In the current study, Wendt and Hesselmann (2024) will investigate the effects of using a dual-task design in a masked priming paradigm, focusing on subjective visibility judgments. Based on power analysis, the study will test 34 participants performing both single-task and several dual-task conditions to measure reaction times and priming effects. Priming is tested via a speeded forced-choice identification of a target. The key manipulation is the non-speeded visibility rating of the prime using a Perceptual Awareness Scale, either with a graded (complex) rating or a dichotomous response. Moreover, participants will either provide their awareness judgement via a keyboard or vocally. Finally, participants will also complete a control condition to test prime visibility by testing the objective identification of the prime. These conditions will be presented in separate blocks, with the order randomised across participants. The authors hypothesise that using a dual-task slows down response times and boosts priming effects. However, they further posit that keyboard responses and graded visibility ratings, respectively, in the dual task reduce priming effects (but also slow response times) compared to vocal responses and dichotomous visibility judgements. In addition to the preregistered hypotheses, the study will also collect EEG data to explore the neural underpinnings of these processes.

 

The Stage 1 manuscript went through three rounds of review by the recommender and five expert reviewers. While the recommender would have preferred to see targeted, directional hypotheses explicitly specified in the design instead of non-directional main effects/interactions, he nevertheless considers this experimental design ready for commencing data collection, and therefore granted in-principle acceptance.

 

 
Level of bias control achieved: Level 6. No part of the data or evidence that will be used to answer the research question yet exists and no part will be generated until after IPA.
 
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Wendt, C. & Hesselmann, G. (2024). Probing the dual-task structure of a metacontrast-masked priming paradigm with subjective visibility judgments. In principle acceptance of Version 4 by Peer Community in Registered Reports. https://osf.io/ds2w5