Complex sentence: He is considered to be one of the fathers of applied behavior analysis (ABA, formerly called Behavior modification) through his development of the Lovaas technique and was the first to provide evidence that the behavior of autistic children can be modified through teaching.
Split into simpler sentences: He is considered to be pioneer within applied behavior analysis (ABA) through his development of the Lovaas technique. He was the first to provide evidence that the behavior of children with autism can be modified through teaching.