This joint attention to objects and events fosters early language development.
( ( ( This ( joint attention ) ) ( to ( ( objects and ) events ) ) ) ( ( fosters ( early ( language development ) ) ) . ) )
(ROOT (S (NP (NP (DT This) (JJ joint) (NN attention)) (PP (TO to) (NP (NNS objects) (CC and) (NNS events)))) (VP (VBZ fosters) (NP (JJ early) (NN language) (NN development))) (. .)))
This joint attention will have the most impact on fostering language development. 
( ( This ( joint attention ) ) ( ( will ( have ( ( the ( most impact ) ) ( on ( fostering ( language development ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This) (JJ joint) (NN attention)) (VP (MD will) (VP (VB have) (NP (NP (DT the) (JJS most) (NN impact)) (PP (IN on) (S (VP (VBG fostering) (NP (NN language) (NN development)))))))) (. .)))