Abstract
Previous studies reported original art paintings were preferable than hue-rotated pseudo art paintings (Kondo et al., 2017) and subjective preference for them tended to be correlated with their naturalness (Taniyama et al., VSS2018). Correspondingly, event-related potentials (ERPs) study showed that P3 amplitude during an oddball task reflects the naturalness of the stimuli (Minami et al., 2009). Here, we aim to investigate the naturalness of the original and pseudo paintings by focusing on the asymmetry of P3 amplitude during an oddball task. Stimuli were selected from “Abstract” and “Flower” categories in WikiArt. They were selected under two conditions: 0–180 deg and 90–270 deg pairs with two target-standard roles (standard-target and target-standard). ERPs were concurrently recorded while an oddball task was conducted with ratio of standard:target = 4:1. On each trial, participants were asked to count the number of the target stimuli in order to focus on the context (silent-counting oddball task). Behavioral results showed that the accuracy of the silent-counting oddball task in the 0–180 pair was higher than the 90–270 pair. This result implies that difference in naturalness between the stimuli pairs was more evident in the 0–180 pair. In parallel with this, P3 amplitude of the target stimuli with 180 deg was larger than those with 0 deg (P3 asymmetry for the 0–180 pair), while no amplitude difference was found for the 90–270 pair. P3 asymmetry is known to reflect unnaturalness and unfamiliarity of visual stimuli, hence this finding supports previous behavioral results (Minami et al., 2009; Taniyama et al., VSS2018). Furthermore, this physiological method using P3 asymmetry elicited by switching the target in an oddball task might be able to estimate the difference of naturalness between two paintings, which is closely related to subjective preference.