1Department
of Psychology,National
Taiwan University<pmho@ms28.hinet.net>
2
Department of Psychology, National Taiwan University
3Graduate
Institute of Linguistics, National Taiwan University
Auditory
perception of English minimal pairs was tested, with or without noise background.
Each subject was interviewed after the test to collect information regarding
their early experience on learning English as a foreign language. Results
showed that age effect was salient only under noise background situation.
Without the interference of noise, most subjects performed well enough
to obliterate any potential differences.
INTRODUCTION
One of the most controversial issues in second language acquisition theories concerns the critical period hypothesis. In the acquisition of first language, lots of evidence lends support to the critical period concept, but the relevance of this hypothesis to second language acquisition seems inconclusive (Harley et al. 1997). Empirical studies concerning this hypothesis differ in their focuses. A recent meta-study by Marinova-Todd, Marshall and Snow (2000) pointed out misconceptions about age effects in second language acquisition. However, in a very recent empirical study (DeKeyser 2000), the robustness of age effects in second language acquisition was again found. By testing how adult learners¡¦ grammatical abilities correlated with their problem-solving capabilities, instead of their starting age of second language learning, this study replicated the findings of Johnson and Newport (1989).
Studies of infant speech perception, however, have revealed that the ability to discriminate non-native phonemic contrasts decreases at around the end of their first half-year of life (Werker et al., 1984). In addition, most adults were found to experience difficulties when differentiating non-native phonetic contrasts. The developmental change of speech perception is thus an aspect that requires more intensive investigation in order to account for facts such as better initial gain for older second/foreign language learners, which seems to contradict results from infant studies.
This exploratory study was conducted with two purposes; first, at the theoretical level, it was designed to weigh the differential effects of learning English at three age starting points and two learning durations; secondly, at the educational/practical level, the study was designed to examine how childhood learning experience of English has affected Taiwanese university students¡¦ auditory competence in distinguishing English minimal pairs.
EXPERIMENT 1
METHOD
RESULTS
Auditory test scores (i.e. correct identifications) of the 66 subjects range from 199 to 238 (out of 240), with an average at 221.50 and a standard deviation at 9.40. Correlation analysis results show that subjects¡¦ age is highly correlated with EXPOSURE (r=0.33, N=66, p<0.01), indicating not only the increasing rate of learning English as a foreign language but at a younger age in Taiwan. Auditory test scores are highly correlated with STRTFRML (r=-0.32, N=66; p<0.01) and fairly correlated with EXPOSURE (0.01<p<0.05), IMMYR, INVSI and NS. IMMYR is barely correlated with test scores (r=0.22, N=66; p=0.08). Reaction time (RT) and correct answered reaction time (CRRT) were not correlated with scores
The results also show that the correlations among all the predictors involving early English learning experiences are highly correlated among themselves. Therefore, a force entry regression entering the predictors by block was conducted.The whole model is not statistically significant (F(9,56)=1.57, p=0.15); only around 20% of the variance can be accounted for by the nine variables altogether. And the R square change values indicate only 7% of the variances uniquely contributed by the three starting points combined. This seemly lower correlation might have been caused by the narrowly distributed scores, which were also skewed to the left. Therefore in experiments 2, a noise background was superimposed to increase the overall difficulties of the task.
Force entry regression results converge with the partial correlation findings. We entered the variables in 5 blocks. Two regression sets were performed separately, with the first three blocks (containing Native Language, Sex, Age, NS, IMMYR, INVIS) entered in the same order, and the last two blocks¡¦ order switched (containing (1) STRTFRML and EXPOSURE and (2) FORMAL). Although the overall F is not quite significant, probably due to small sample size in relation to the number of predictors and of levels of some of the predictors (F(9,56)=1.549, p=0.139), this force entry regression analysis can still provide us with very important information. Results show that the first three blocks altogether contributed only 3% of the response variation, and FORMAL alone contributed 1% of the variation if entered last. In addition, EXPOSURE and STRTFRML as a block, if entered last, can independently contributed above 10% of the variation. Both correlation and force entry regression analyses results reveal that immersion experiences (including both duration and starting point information) are no longer statistically valid predictors under noisy testing condition.
As infants become older and gain more experience of their ambient languages, their tendency to react to non-phonemic contrasts declines (Wode, 1994). Theoretically, the reorganization of their phonological system can be either in an all-or-none, or in a gradient fashion. What we have found in this study is that speech perception may not be an all-or-none ability. Under noisy testing condition, the earlier people are exposed to English or learn English in formal settings, the more likely they can perform relative better then late starters. That is, early starters¡¦ ability to access their non-native speech perception system are better than late starters¡¦, but this pure effect of age cannot be measured with some tasks, for example, our no-noise testing condition. Under noise condition, acoustic information was not as salient as it was without the noise. Without the noise, subjects might be able to use all kinds of acoustic information provided by the speech input, even if they do not have any immersion experiences or are late starters. At practical level, performance of NTU students on our task reflects age effect, especially under noise condition. However, starting early does not guarantee better ultimate gain individually.
Our findings suggest further research is needed in the following directions: (1) examining the relationship among our perceptual testing scores and other English language tasks such as Johnson and Newport’s (1989) syntactic test; (2) designing tailored interviews according to our current data to precisely collect early English learning experience that might cause performance differences on the task; (3) examining relationship between different instruction methods and correspondent learning pattern.
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