The critical period is important in learning language by a human baby. It is during this period that the language acquisition device (LAD) is active for language learning. It is assumed that beyond this period, the LAD is inactive and therefore, one cannot acquire language.
The only case that comes to mind was this one girl who was abused by her family by neglecting her and never speaking to her. When it was found out, she was already past the critical period. While the girl could learn words, she would never remember them. However, in Sign Language there was more improvement in grammar for her than with verbal language. Maybe reading up on her case may be a good start?
Following up on Alron Kevin Agapito Arzaga's comment, the case study can be found here: https://www.jstor.org/stable/412222?seq=1
I think it's hard to know whether her language skills were lacking due to not learning a language before a "critical period" or parental abuse or a disability. I think that the last explanation (mental disability) is pretty compelling. But it is hard to know for sure.
This is an interesting question which brings to mind the following publication: Oliver Sachs (1989) Seeing Voices. The text includes a detailed discussion on language development and sign.
- Badges
- Science topic
- Similar topics
- Psychology
- Mental Processes
- Learning