As search becomes increasingly mobile, getting closer to being the majority of search visits every month, how we think about user engagement on search results needs to be updated from the old desktop paradigms of the Golden Triangle (which suggest attention sticks to the upper left and decays down and to the right).
Mobile search use cases and device features change the way users distribute their attention on a search result page. Not only does this change CTR curves for mobile, and the relative value of each position, it also changes how search engines evaluate usage metrics and satisfaction. This is compounded by the presence of Knowledge Graph (entity results, panels, and carousels) and Instant Answers (weather, scores, etc.) which may satisfy a users query without logging a click or scroll.