At the end of the second year, children begin to label their own and others' internal states with words, such as  want,   happy,   mad,   think,  and  pretend. 
( ( At ( ( the end ) ( of ( the ( second year ) ) ) ) ) ( , ( children ( ( begin ( to ( ( ( ( ( ( ( label ( ( ( their own ) and ) ( ( others ' ) ( internal states ) ) ) ) ( with ( ( ( ( words , ) ( such ( as want ) ) ) , ) ( happy ( , mad ) ) ) ) ) , ) think ) , ) and ) pretend ) ) ) . ) ) ) )
(ROOT (S (PP (IN At) (NP (NP (DT the) (NN end)) (PP (IN of) (NP (DT the) (JJ second) (NN year))))) (, ,) (NP (NNS children)) (VP (VBP begin) (S (VP (TO to) (VP (VP (VB label) (NP (NP (PRP$ their) (JJ own)) (CC and) (NP (NP (NNS others) (POS ')) (JJ internal) (NNS states))) (PP (IN with) (NP (NP (NP (NNS words)) (, ,) (PP (JJ such) (IN as) (NP (VP (VB want)))) (, ,)) (ADJP (JJ happy) (, ,) (JJ mad))))) (, ,) (VP (VB think)) (, ,) (CC and) (VP (VB pretend)))))) (. .)))
Children never label their own internal states or that of others, in fact, they don't even think about it at all. 
( ( Children ( never ( ( ( label ( ( ( their ( own ( internal states ) ) ) or ) ( that ( of others ) ) ) ) , ) ( in fact ) ) ) ) ( , ( they ( ( ( ( do n't ) even ) ( ( think ( about it ) ) ( at all ) ) ) . ) ) ) )
(ROOT (S (S (NP (NNP Children)) (ADVP (RB never)) (VP (VBP label) (NP (NP (PRP$ their) (JJ own) (JJ internal) (NNS states)) (CC or) (NP (NP (DT that)) (PP (IN of) (NP (NNS others))))) (, ,) (PP (IN in) (NP (NN fact))))) (, ,) (NP (PRP they)) (VP (VBP do) (RB n't) (ADVP (RB even)) (VP (VB think) (PP (IN about) (NP (PRP it))) (ADVP (IN at) (DT all)))) (. .)))