Definitions for Learning Conditions

Adoptees Learning a New Language child L2 learner whose L1 exposure was abruptly stopped as a result of adoption to a different country
Attrition (partial) loss of previously fluent language, effect of L2 on L1
Autism autism spectrum disorders, Aspergers syndrome
Brain Injury focal brain injury, hemispherectory
Cochlear Implant individuals with a cochlear implant
Deaf / Hard of Hearing individuals with a significant hearing loss
Downs Syndrome Downs syndrome
Dyslexia dyslexia
Fragile X Fragile X
General Language Delay general language delay (not included in other more specific categories)
Heritage Language Learner L1 ability of native speaker of minority language who is learning a majority language at school (e.g. ability in Mexican Spanish of child living in the USA and learning English at school), effect of majority L2 on maintenance of minority L1
Majority Language Learner L2 learning of majority language, primarily through school exposure, by native speaker of minority L1 (e.g. English language learner in USA whose home language is Mexican Spanish, Dutch learner in Netherlands whose home language is Turkish)
No Human Subjects no human subjects – theoretical model
Preterm Children children born significantly preterm
Simultaneous Bilingualism / Trilingualism simultaneous bilingualism or trilingualism (learning two or three languages from before age 3)
Specific Language Impairment specific language impairment
Typical First Language Development first language development in a typical manner
Typical Adult Second Language Development adult second language acquisition (learning one language after another is established, whatever the endstate proficiency)
Typical Child Second Language Development child second language acquisition (learning one language after another is established, whatever the endstate proficiency)
Visual Impairment visual impairment
Williams Syndrome Williams syndrome