Second Language Acquisition and Second ... - Stephen Krashen

second language acquisition in adult and one which could imply lowered
expectancies on the part of both teachers and students.
Since 1967, however, there have been some encouraging research reports. While
there seems to be no question that puberty is an important turning point in language
acquisition (see, for example, Seliger, Krashen, and Ladefoged, 1975), it is not at all
clear that the development of cerebral dominance is directly related. Second,
alternative explanations are available to explain child-adult differences,
explanations that are far more encouraging than the biological one. We will first
briefly review the "state of research" over the last decade on the question of the
development of cerebral dominance, and then review one of these alternative
explanations.
Simply, it is no longer clear that the development of cerebral dominance is complete
at puberty. There are now arguments supporting the position that lateralization is
"firmly established" much earlier, at least by age 5, and that the preconditions for
lateralization may be present even at birth. Below, we briefly summarize the
experimental and clinical literature that has appeared on this topic in the last few
years. As we shall see, most of the reports support "early" lateralization. There are,
however, some apparent inconsistencies that we discuss below.
1. Dichotic listening. Witelson (1977) has reviewed all known studies using dichotic
listening with children and concludes that "... of 36 experiments, 30, or about 83 per
cent, reported right-ear superiority for their youngest subgroups, and all found rightear
superiority in at least older subgroups" (p. 230) (where "younger" indicates from
about age 3 to about 7). Studies evaluating developmental trends usually report no
increase in degree of lateralization over time (age), supporting the hypothesis that
language lateralization is firmly established far earlier than puberty, A few studies,
however, do in fact report an increasing right-ear advantage up to about puberty,
consistent with Lenneberg's position. What is interesting about these studies (e.g.
Satz, Bakker, Teunissen, Goebel, and Van der Vlugt, 1975) is that the stimuli used
for dichotic presentation were slightly different from the stimuli used in studies that
report no change in degree of lateralization with increasing age. In the "puberty"
studies, the children were presented with two or three sets of digits at one time
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