Dr. Laura Ann Petitto recently learned that her research discovery on the existence of manual babbling in deaf babies exposed to signed languages was named one of the top 20 studies since 1960 in the history of Child Development. The top 20 studies resulted from a survey conducted by Dr. Wallace Dixon that was published in The Society for Research in Child Development  newsletter in 2014. See Page 8:

http://www.srcd.org/sites/default/files/documents/57-1.pdf

The highlighted study, placed at number 7 (out of 20), is as follows: Petitto, L. A. & Marentette, P. (1991). Babbling in the manual mode: Evidence for the ontogeny of language. Science, 251, 1483-1496. View Document