( ( ( EXPERIMENT 3 ) ( ( One factor ) ( which ( ( had not ) ( ( been systematically ) ( ( controlled up ) ( to ( this point ) ) ) ) ) ) ) ) ( ( was ( ( the behavior ) ( of ( ( the ( other birds ) ) ( in ( the ( animal room ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (QP (CD EXPERIMENT) (CD 3)) (NP (CD One) (NN factor)) (SBAR (WHNP (WDT which)) (S (VP (VBD had) (RB not) (VP (VBN been) (ADVP (RB systematically)) (VP (VBN controlled) (PRT (RP up)) (PP (TO to) (NP (DT this) (NN point))))))))) (VP (VBD was) (NP (NP (DT the) (NN behavior)) (PP (IN of) (NP (NP (DT the) (JJ other) (NNS birds)) (PP (IN in) (NP (DT the) (NN animal) (NN room))))))) (. .)))
EXPERIMENT 3 One factor which had not been systematically controlled up to this point was the behavior of the other birds in the animal room.
(ROOT (S (NP (NNP Animal) (NNS behaviors)) (VP (VBP are) (VP (VBN controlled) (PP (IN by) (NP (NP (DT both) (NNS genes) (CC and) (NNS experiences)) (PP (IN in) (NP (DT a) (VBN given) (NN envionment))))))) (. .)))