Even short-term studies found the younger, the better.
Tahta, wood and Loewenthal(1981a) found learners’ pronunciation aspect of language declined with increasing age.
In long-term studies, those comparing achievement after several years of foreign language study and or residence in the SL environment, younger starters consistently outperform older ones, only quite younger children seem to be capable of native-like attainment. Start after 6, there will be accent.(P157)
6.2.1 studies of age and SLA
As noted by Krashen, Long and Scarcella(1979),some fairly clear patterns emerge. The conclusion is that older is faster, but younger is better. As revealed by long-term studies, yonger is better in ultimate attainment. Quite young starters achieve accent-free, native like performance.
Oyama(1978)found strong negative effect for subjects’ AOA in the USA and their ability to comprehend masked speech. Children arriving before 11 performed similarly to NS controls, with later arrival showing decline with age.
Short-term studies speak only to differential rate of acquisition, not to absolute abilities. They favor older learners because of their “teach and test”, greater cognitive development and test-wiseness.
6.2 Age
Some claim that SLA is the same process and just as successful whether learners begin as a child or adult or/that adults learn faster. Others think adults are at a disadvantage only in a few areas, esp. phonology. Younger learners are at an advantage in ultimate levels of attainment, such as accent-free SL performance.
Scovel(1981) provide evidence of the age-related evolution of accent recognition in native speakers and of a sensitive period for accent recognition in non-native.
As revealed by short-term studies, adults faster than children. The rate advantage is limited in several ways, in early morphology and syntax, it is temporary. Younger adults outperform older adults even in short-term studies.
2. older children acquire faster than younger children. Ekstrand(1976) older children performed better than younger children . Fathman found older do better in syntax and morphology, younger do better on pronunciation.
Importance of this issue
Theoretically, whether L1 acquisition and L2 acquisition are the same, whether they use the same mechanism. Practically, people in teaching programmes want to know the optimal timing for language programmes. Whether there is a critical period for each domain of language?
Findings of these studies
SL phonological attainment is strongly conditioned by learner age, specifically that attainment is inversely related with AOA and a native like accent is impossible unless first exposure is quite early probably around 6.
Lstudies
1. the subjects are elite few, the finding is not generalizable. 2. the speech sample is limited. 3. wording of instruction to the rater influence their judgment. The findings do not constitute counter-evidence to the idea that there is a sensitive period for SL phonology.
In addition to age, language aptitude, social-psychological factors, personality, cognitive style etc also explain the differential success among learners. Factors presented in this chapter are not the only variables that influence SLA, other variables like input, instruction, L1 influence also have impact.
Chapter 6:Explanations for differential success among second language learners

6.1 Introduction 6.2 age 6.3 aptitude 6.4 social-psychological factor 6.5 personality 6.6 cognitive style 6.7 hemisphere specialization 6.8 learning strategies 6.9 other factors 6.10 conclusion
Oyama(1976) pronunciation ability with different age of arrival(AOA) found effect of AOA not LOR. Asher and Garcia(1969) the younger the better. Major(1987) support the critical period hypothesis for accent.
6.1 Introduction
Language mastery is not often the outcome of SLA. There is a much broader range of language proficiency achieved among second language learners than first. One of the most obvious potential explanations for comparative lack of success of second language learners is that SL learners begin acquiring the language at a later age than do first language learners.
Generalization by Krashen (1979)
1. Adults proceed through early stages o syntactic and morphological development faster than children( where time and exposure are held constant). Age-related constraints begin to set in as early as 6 for phonology. The existence of critical period (Lennenberg 1967)after which complete master is impossible or sensitive period during which language acquisition is most efficient.