[a-priori]

Dr. Marilyn Daniels at Penn State University has found that hearing students in pre-kindergarten classes who receive instruction in both English and ASL score significantly higher on the Peabody Picture Vocabulary Test than hearing students in classes with no sign instruction.

Thanks for providing these articles. I don't doubt that children can learn to sign before they can learn to speak (not a big leap considering that babies can understand language before they can move their vocal muscles well enough to produce it), or that they'd be happier being able to communicate earlier.

What I do doubt is that this has any long-term effects on their development, above and beyond the effect of learning more than one language. In any of the longitudinal studies, do they control by having a second group of infants learn two spoken languages?

[3pt14159]

Anecdotal, I know, but the smartest guy I know (13 courses one semester at Waterloo, qualified to major in CS, actuary science, accountancy, pure math with minors in psychology and business. Currently working on his law degree, actuary tests, and CFA (certified financial advisor) while working full time as a chartered accountant) was taught baby sign as an infant. His younger brother was not. His younger brother is so much more creative and broad thinking whereas the eldest is a Spock like linear thinker. Trade offs.