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Study

Using the Aesop’s Fable paradigm to investigate causal understanding of water displacement by New Caledonian crows

Jelbert, Sarah A.; Taylor, Alex H.; Cheke, Lucy G.; Clayton, Nicola S.; Gray, Russell D.

PLoS ONE, 2014

Peer-reviewedcontrolled laboratory experimentcaptive

What they did

Crows were given a floating reward in a water tube and objects to drop in, across tasks varying whether objects sank or floated, were solid or hollow, and whether the tube contained water or sand — including a condition with two tubes connected out of sight beneath the table.

Studied in
Corvus moneduloides
Sample size
6 wild-caught crows across six water-displacement tasks

What they found

Crows chose sinking over floating objects, solid over hollow, and water over sand. They failed the task requiring them to understand that two visibly separate tubes were connected underneath.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

The crows show a good grasp of the causal properties they can see, and no grasp of a hidden causal connection.

How NatureHQ reads it

The failure is the valuable result and the reason this study is here. A record that only reports successes produces the impression of a bird that understands physics; the pattern is much more specific than that, and much more informative. Visible causes yes, unobservable mechanism no — which is roughly where a five-to-seven-year-old human child also sits on this task.

Limitations

  • Six birds, some tested on several tasks in sequence with possible carry-over.
  • Object preferences could partly reflect handling properties rather than predicted effects.
  • Comparisons with child performance come from different laboratories and procedures.

The experiment, explained

  • Six water-displacement tasks, and the one the crows failed

    New Caledonian crows drop stones into water to raise a floating reward. Do they understand why it works?

What this study is used for on NatureHQ

One study can inform several subjects. Here is everywhere this one is cited.

Finding the paper

Published by: Public Library of SciencePublished in a PLOS journal under CC BY 4.0.

doi.org/10.1371/journal.pone.0092895

This reference was resolved automatically against Crossref on 2026-08-11.

NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-08-09.