This MIT, Stanford, New York Univ, Princeton, study shows that while people expected AI to save time on simple tasks, but it mostly saved effort instead.

Across 1,237 people, participants predicted that AI help would cut about 69 seconds from task time.

In the real task group, AI help did not meaningfully reduce total completion time overall.

The gap came from a speedup illusion, where people judged their own solo time fairly well but badly underestimated AI-assisted time.

AI did help on some harder tasks, such as longer summarizing or editing, but it did not help much on easy tasks.

The important twist is that AI made tasks feel easier, even when it did not make them faster.

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To note, the biggest limitation is that this study used short, simple tasks that could be finished in under 5 minutes, so it does not test long report reading, synthesis, cross-checking, and analysis work where AI can compress hours into minutes.

It also used crowdworkers doing one-off tasks in a controlled setting, so it misses expert users with strong prompting habits, personal context, repeated workflows, and clear business goals, where gains can be much larger.

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– arxiv. org/abs/2605.23177

Title: "Cognitive offloading and the speedup illusion in human-AI interaction"