Appendix 2—figure 9. The 50 hardest images from Appendix 2—figure 7 where difficulty decreases left-to-right, top-to-bottom.

Images chosen for the main experiment as ‘texture-like’ are circled in red. Images from the MIT 1003 dataset (Judd et al., 2009, https://people.csail.mit.edu/tjudd/WherePeopleLook/index.html) and reproduced under a CC-BY license (https://creativecommons.org/licenses/by/3.0/).