I am so long away from that I hesitate to say anything! Back in the sixties Bill Gibson, Robt Howren, and I (at Wendel Johnson Speech & Hearing) tried to devise a sorting program looking for syntax indicative of the language acquisition period - in children. We examined a large amount of text taken from recordings of children etc. We had a number of people looking over our shoulders as we tried to develop this 'algorithm' - people in linguistics, neurology, education, ed-psych measurement etc. My wife was doing her student teaching at the Area Development Center in Davenport, Ia at the time so I went went with her and began recording the speech patterns of handicapped children. I was interested in comparing that population with samples from 'normal' non-institutionalized children. The fit was good. I decided to compare that data with a large sample of data from Downes clients, ages 2-25, and was surprised by the results. Our program suggested that the Downes clients were engaging in 'acquisition like' speech patterns skewed to ages 18-25! I consulted with the director of the center and she smiled and said: 'yes. its a syndrome we've seen for years...it usually stops by age 25'. A colleague Bob Wachal noted that he thought he had seen similar linguistic 'experimentation' in patients trying to recover from brain injuries... obviously there must be a neurological basis for anything like this regardless of the age and condition of people entering such a phase ? The whole thing became an interesting academic exercise. Bill Gibson and I were using PL1 ... about 1968. Work of this kind has advanced light years beyond where we were in those early years using PL1 ... I think Bob Wachal went further with his work on Aphasia. Its a neurological issue of importance for anyone who has a brain injury affecting language skills ...