The item-specific proportion congruency effect transfers to non-category members based on broad visual similarity

The item-specific proportion congruency (ISPC) effect-that Stroop effects are reduced for items that are more likely to be incongruent than congruent-indicates that humans have the remarkable capacity to resolve conflict when it is associated with statistical regularities in the environment. It has been demonstrated that an ISPC signal induced by mostly congruent and mostly incongruent inducer items transfers to a set of distinct but visually similar transfer items that are equally likely to be congruent and incongruent; however, it is unclear what the ISPC signal is associated with to allow its transfer. To investigate this issue, an animal Stroop task was used to evaluate whether the ISPC signal would transfer to animal pictures that were different but visually similar same-category members (e.g., retrievers to retrievers, Experiment 1), visually dissimilar same-category members with broadly similar features (e.g., retrievers to bulldogs, Experiment 2), and visually dissimilar different-category members with broadly similar features (e.g., retrievers to house cats, Experiment 3). It was revealed that an ISPC effect was observed for the transfer items of each experiment, suggesting that these conflict signals can be linked based on broad feature similarity.