Pokémon scenes and pixelated faces fMRI control experiment.

To evaluate whether the information we observed in the OTS in experienced participants for Pokémon was selective for the learned game characters and not just any stimulus from the game, a subset of experienced participants (n = 5, 3 of whom also completed the pRF mapping detailed in the following section) was invited back to the laboratory to complete a follow-up fMRI experiment containing two categories of images. The first consisted of scene stimuli from the Pokémon game. These scenes were map-like images extracted from the game through which the player has to navigate their character, including towns, natural landscapes and indoor spaces. These scenes were free of any images of people or Pokémon. The second category of stimuli was human faces (from the main experiment) downsampled to visually resemble the 8 bit pixelated images from the Pokémon game to match for low-level visual features. This was accomplished by resizing face stimuli to 70 × 70 pixels (approximately the original pixel size of Pokémon characters) and then resizing again using bicubic sampling to their original size of 768 × 768 pixels. Images were presented in 4 s blocks at a rate of 2 Hz and were interleaved with a blank baseline condition. There were 12 blocks of each condition in a run; each run was 162 s in duration and participants completed 3 runs. Data were analysed similarly to the main category localizer. Participants were instructed to press a button when a blank image appeared within a block of images (oddball detection task).