Two images are presented. The participant decides if they represent the exact same phenomenon, quantity, feature or object. When math symbols are presented the participant decides if the operations are the same ( e.g. A + B, and B + A, same or not same).
We work with the presentation of two, and only two, images side-by-side, not three or more images or objects? Why not use the flashcard approach of presenting only one problem with the expectation of the participant providing an “Answer?”