Crowding of Upright Chinese Character is Stronger with Inverted than Upright Flankers: An Exception of the Similarity Rule

Upright flanking faces have stronger detrimental effects on the recognition of upright target face, than inverted flanking faces. One possible explanation for this “flanker- inversion effect” was that the more holistically processed upright flanking faces allowed for more erroneous feature integration. Alternatively, crowding was known to be stronger when target and flankers were more similar. Here we investigate flanker-inversion effect on crowding in Chinese character identification. Five normally-sighted young adults participated. Targets of size 1.2° were presented at 5° in the lower visual field. Four flankers with center-to-center distance of 1.8° were presented in the crowded condition. Three types of flankers were used, upright or inverted Chinese and upright Korean characters. The identification contrast thresholds were estimated by QUEST and crowding strength was measured through threshold elevation (TE). Crowding on upright Chinese target was significantly stronger with inverted Chinese flankers (TE = 1.59±0.32) than with upright Chinese flankers (TE = 1.47±0.29). No inversion effect was observed for inverted Chinese target. Korean flankers produced similar crowding as upright Chinese flankers. Our results go against the similarity rule that predicts upright Chinese flankers would produce stronger crowding for upright Chinese target. Holistic processing preferred for inverted Chinese characters may account for the findings.