Even a single trivial binding of information is critical for fluid intelligence

General fluid intelligence—the individual ability for abstract reasoning that predicts many professional and daily-life outcomes—has been linked to the efficacy of processing relations. However, how simple relations still require fluid intelligence remains elusive. Across six studies (N = 1040) using the transitive reasoning task, the amount of information to be bound together to select the correct option was consecutively simplified, from binding four symbols into a monotonic order, to trivial finding of the exact copy of a symbol triplet that relayed no meaningful relationship. Even the simplest variants correlated with fluid intelligence almost as strongly (rs around 0.50) as the regular intelligence tests (rs around 0.60). Only when symbols were chunked into one representation was fluid intelligence no longer relevant. These results suggest that even a single trivial binding of simple information is critical to fluid intelligence. •Complexity of element bindings systematically decreased in a dedicated task.•Six studies looked for the simplest binding predicting fluid intelligence (gf).•Even trivial bindings loaded on gf almost as strongly as intelligence tests.•However, items that did not require bindings did not predict gf.•Ability to construct reliable and stable bindings seems critical to gf.