Complex sentence: The Wug Test was created in by Jean Berko Gleason in 1958 as a method of determining the progression of the acquisitionof the allomorphs of the plural morpheme in English-speaking children.
Split into simpler sentences: The Wug Test was created by Jean Berko Gleason in 1958. It was designed as a way to analyze the acquistion of the plural morpheme in English-speaking children.