In their study, Neuman and Koskinen (1992) investigated whether comprehensible
input, delivered by captioned television programmes, affected the acquisition of
vocabulary and of conceptual knowledge. The participants were children in immersion
programmes, and the video material was of science lessons. They picked out 90 of the
most difficult words from these video lessons as target words, 10 for each week. Participants were assigned to one of four treatment groups: captioned TV, TV without
captions, reading along and listening to the soundtrack, and reading only. Results for
the vocabulary acquisition strand of their study, which used word recognition tests and
tests of the words in context sentences, showed that the captioned TV group performed
consistently better (see Danan, 1992).