It is unique humanity to exhibit an aesthetic preference for displeasing artworks. Although prior works explained this with processing fluency, there is space for theoretical and methodological elaboration. Through two experiments, we aim to disentangle the distinguishable contribution of conceptual fluency in preference for artworks eliciting negative valence from the role of perceptual fluency. We manipulated conceptual fluency by semantic priming (experiment 1), and perceptual one via controlling visual contrast (experiment 2). We measured perceivers' valence, preference, and subtypes of fluency for artworks inducing various valence. With these data, the hedonic and amplifying effects of fluency in aesthetic preference were tested. Also, we recorded their eye movement during art appreciation to precisely capture their processing style varying on the level of fluency. Results of both experiments support that only conceptual fluency directly and indirectly affects art preference. It directly increased preference and attenuated inhibitory effects of negative valence on art preference. This suggests that the amplifying model for fluency does not fit the context of art appreciation. Furthermore, eye tracking analysis revealed that all groups performed automatic processing regardless of contrast level in experiment 2. However, the primed group conducted controlled processing, unlike the not-primed group in experiment 1. With the pleasure- interest model of aesthetic liking ('PIA model', Graf & Landwehr, 2015), this result emphasizes the role of conceptual fluency via semantic priming in aesthetic preference. Generally, our study purposed to refine the amplifying theory of processing fluency and the PIA model to underpin their potential in empirical aesthetics.