What is the most effective second language vocabulary learning method?

Research suggested retention rate of an item increased when one was trained byretrieving the item. The present study will empirically investigate whether the benefit apply in learning second-language vocabulary. In this study, we asked native-Chinese speaker to study 48 English Chinese word pairs with 4 different training methods (productive vs. receptive vs. productive + picture, restudy). Their knowledge was assessed in two days using productive or receptive final test. Result indicated retention rate is higher using retrieval compared to restudy. Additionally, we found training in one-direction (e.g. productively) lead to substantial knowledge in the opposite-direction (e.g. taking a receptive posttest) except taking a productive posttest with receptive training. Our result also suggested that adding pictorial stimuli to productive training may be better than productive training alone. Theoretical and practical implication were discussed.