( ( Problem gamblers ) ( ( ( change ( negative feedback ) ) ( into ( ( a sort ) ( of ( positive feedback ) ) ) ) ) . ) )
(ROOT (S (NP (NNP Problem) (NNS gamblers)) (VP (VBP change) (NP (JJ negative) (NN feedback)) (PP (IN into) (NP (NP (DT a) (NN sort)) (PP (IN of) (NP (JJ positive) (NN feedback)))))) (. .)))
Problem gamblers change negative feedback into a sort of positive feedback.
(ROOT (S (NP (JJ Positive) (NN feedback)) (VP (VP (VBZ intensifies) (NP (NP (DT a) (NN change)) (PP (IN in) (NP (NP (DT the) (NN body) (POS 's)) (JJ physiological) (NN condition))))) (CONJP (RB rather) (IN than)) (VP (VBG reversing) (NP (PRP it)))) (. .)))