“…Finally, we also took into account the subject-related cognitive challenge, that is, the subjective reactions evoked by an artwork. Amongst various estimates of cognitive challenge studied in empirical aesthetics (Jakesch & Leder, 2009;Jakesch et al, 2013;Muth & Carbon, 2013;Muth et al, 2015), we chose to focus on perceived inconsistency, complexity, and ambiguity, as these measures allowed us to capture different aspects of cognitive challenge in contemporary art. Whereas "ambiguity" is often associated with multiple meanings and interpretations that could be attributed to the stimuli (Muth et al, 2015), "complexity" usually refers to more formal aspects, such as variety of elements and ways they are organized (Nadal, Munar, Marty, & Cela-Conde, 2010).…”