Does prior knowledge increase or decrease perceived visual complexity of texture images?

Previous research has shown that the perceived visual complexity of an image is correlated with understandability of the image. It was considered that prior knowledge of the contents of an image makes images easier to understand, and thus reduces perceived visual complexity. In the present study, we examined the effect of prior knowledge on perceived visual complexity of texture images. We designed an experiment in which participants observed and rated four texture images with different levels of complexity and understandability; one group of participants received prior knowledge in the form of verbal cues about the names of the target stimuli while the other group did not receive any information regarding image content. We found that the effect of prior knowledge on visual complexity perception varied for the different images. For an image with low initial complexity, if cued information about the image is three-dimensional or dynamic, prior knowledge does not decrease but instead increases the perceived visual complexity. Moreover, cues that increase perceived visual complexity can be verbal rather than visual cues.