Author's response to reviews Title: Television viewing in Thai infants and toddlers: impacts to language development and parental perceptions Authors:

In the final sentence of the conclusion, the word “however” is not necessary. In the revised manuscript, we have removed the word “however” from the final sentence of the conclusion, as suggested by the reviewer. Introduction, page 4: “younger than 2 years should avoid from electronic screens” cut the word from. And in the same paragraph, “the viewing time should not excess” replace excess with exceed. The sentence “younger than 2 years should avoid from electronic screens” on page 4 has been cut and the word “excess” was replaced by “exceed”. This is highlighted for the benefit of the reviewer. Page 4 According to the American Academy of Paediatrics (AAP), electronic screens viewing time should not exceed 2 hours per day [7]. Introduction, page 5, top. Rather than list TV shows that enhance development, can the authors describe them, noting important characteristics? The above comment from the reviewer is very useful. We have addressed important characteristics of the programmes in the revised manuscript and have been highlighted on page 5. Page 5 Some children’s television programmes, where onscreen characters speak directly to the child, actively participate, label objects, contain vocabulary words and their definitions, and provide the child to respond, such as Dora the Explorer, Blue’s Clues, Dragon Tales, Arthur and Clifford, may enhance children’s language development. On the other hand, some programmes that have loose narrative structure and poor language models such as Sesame Street and Teletubbies were associated with reduced vocabulary in the children [14]. Methods, page 7, Assessment of language development. It would be interesting to know how the authors modified the CLAMS, if it can be stated briefly. A sentence describing that “delayed development” was defined, as opposed to documented, when the child failed all items at the 21 month level, because such results mean that the child is functioning at less than 87.5% age expectations. We thank the reviewer for the comments above. We have stated how we modified the CLAMS on page 7 in the revised manuscript. Also, we have changed the sentence regarding the definition of “delayed development” on page 7, as suggested by the reviewer. Page 7 Assessment of delayed language development was carried out by using standardized instrument, modified Clinical Linguistic Auditory Milestone Scale (CLAMS) [16]. The CLAMS was modified to fit Thai cultures and was translated from English into Thai. All pictures in modified CLAMS depicted the same items as the original CLAMS, except the picture of a dog. The dog picture was administered to children in all regions of the country except in the south, where dog is not a common pet. Therefore, a goat, which is usually seen in most families, was selected to substitute the dog picture. All administrators using the modified CLAMS received training by the developmental and behavioural paediatrician and were supervised during its administration. “Delayed language development” was documented when the child failed all items at the 21 months of age which meant the child was functioning at less than 87.5% age expectations. Results: The statement, “Findings from the study have confirmed the association between early television viewing and time spent on television viewing when the children were 2 years old” requires justification. The correlations should be presented. The sentence “Findings from the study have confirmed the association between early television viewing (i.e. at 6 months old) and time spent on television viewing when the children were 2 year old” (page 8) has been removed from the revised manuscript. Discussion: I would suggest that the paragraph that was added to page 10 be considered a limitation and moved back to just before the conclusion. The paragraph stated that “In this study, modified CLAMS was used to identify children with delayed language development. Different cultures may also limit the use of original CLAMS in identifying children with delayed language development. We have also concerned that administering only the items at 21 months of age may affect a number of children with delayed language development reported in this study.” was moved back to before the conclusion on page 13 in the revised manuscript, as suggested by the reviewer.