English: In her dissertation and subsequent journal publication, w:Jean Berko Gleason developed the wug test to demonstrate how children learn English w:morphology.

The papers were published in the US in 1958, and a facsimile of the Word article provided by its publisher does not show a copyright notice suggesting the image is in the public domain for failure to comply with copyright requirements. Even if a copyright notice were visible, searching Stanford's copyright renewal database shows that the work was never renewed and is thus in the public domain.

Other investigations into the copyright status have come to the same conclusion. Dr. Gretchen McCulloch and the team at Lingthusiasm hired a lawyer to investigate the copyright status of this image. They requested documents demonstrating copyright from Gleason in April 2020 and none were provided. On the advice of their lawyer, they maintain that no copyright was ever issued and were it issued, it was not renewed.