Speech sounds that contain multiple phonetic cues are often difficult for foreign-language learners, especially if certain cues are weighted differently in the foreign and native languages. Greek adult and child speakers of English were studied to determine the effect of native language on second-language (L2) cue weighting and, in particular, to explore whether perceptual training could help to improve accuracy in phoneme identification and discrimination. Two forms of stimuli were used: natural (unedited) stimuli and "modified" vowel duration stimuli which were edited to ensure that duration could not be used as a cue in the tasks. Results show the Greek speakers performed poorly when they were unable to use the duration cue as compared with the native English speakers. After high-variability training, performance was improved for both Greek adult (20-30 years) and child (7-8 years) groups. However, the degree of improvement was most pronounced for children. This suggests enhanced plasticity for spoken language in this developmental stage. These data have impact on informing the strategies used for teaching spoken language in English as additional language (EAL) populations in different age groups. (Contains 14 figures.)