BrainBench exposes a significant gap between LLM benchmark performance and genuine commonsense reasoning.
arXiv · March 17, 2026 · 2603.14761
The Takeaway
This benchmark demonstrates that frontier models like GPT-4o fail simple logic puzzles that humans solve instantly, revealing a reliance on surface heuristics. It provides a critical diagnostic for researchers aiming to move beyond stochastic reasoning toward robust common sense.
From the abstract
Large language models (LLMs) achieve impressive scores on standard benchmarks yet routinely fail questions that any human would answer correctly in seconds. We introduce BrainBench, a benchmark of 100 brainteaser questions spanning 20 carefully designed categories, each targeting a specific commonsense reasoning failure mode in LLMs. Categories range from implicit physical constraints ("Should I walk or drive my rental car to the return lot?") to semantic scope tricks and default assumption hija