Lakhasly

AND EXPLICIT KNOWLEDGE As we have seen, there is broad consensus that the acquisition of an L2 entails the development of implicit knowledge+ However, there is no consensus on how this is achieved; nor is there consensus on the role played by explicit knowledge+ The UG position, as articulated by Gregg ~1989!, is that acquisi- tion has nothing whatsoever to do with explicit knowledge+ Cognitive accounts of L2 acquisition, however, are much more mixed+ Traditionally, the relation- Downloaded from https://www.cambridge.org/core.https://doi.org/10.1017/S0272263105050096

144 Rod Ellis ship between the two types of knowledge has been discussed in terms of the interface between them, as shown in the following discussion of three dis- tinct cognitive perspectives+ According to the noninterface position, implicit and explicit L2 knowledge involve different acquisitional mechanisms ~Hulstijn, 2002; Krashen, 1981!, are stored in different parts of the brain ~Paradis, 1994!, and are accessed for performance by different processes, either automatic or controlled ~R+ Ellis, 1993!+ In its pure form, this position rejects both the possibility of explicit knowledge transforming directly into implicit knowledge and the possibility of implicit knowledge becoming explicit+ However, in a weaker form of the noninterface position, the possibility of implicit knowledge transforming into explicit is recognized through the process of conscious reflection on and analysis of output generated by means of implicit knowledge ~Bialystok, 1994!+ In contrast, the strong interface position claims that not only can explicit knowledge be derived from implicit knowledge but also that explicit knowl- edge can be converted into implicit knowledge through practice; that is, learn- ers can first learn a rule as a declarative fact and then, by dint of practice, can convert it into an implicit representation, although this need not entail the loss of the original explicit representation+ The interface position was first formally advanced by Sharwood Smith ~1981!IP address: 182.209.114.22, on 10 Sep 2018 at 01:31:01, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms.

AND EXPLICIT KNOWLEDGE
As we have seen, there is broad consensus that the acquisition of an L2 entails the development of implicit knowledge+ However, there is no consensus on how this is achieved; nor is there consensus on the role played by explicit knowledge+ The UG position, as articulated by Gregg ~1989!, is that acquisi- tion has nothing whatsoever to do with explicit knowledge+ Cognitive accounts of L2 acquisition, however, are much more mixed+ Traditionally, the relation-
Downloaded from https://www.cambridge.org/core. IP address: 182.209.114.22, on 10 Sep 2018 at 01:31:01, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0272263105050096

144 Rod Ellis
ship between the two types of knowledge has been discussed in terms of the interface between them, as shown in the following discussion of three dis- tinct cognitive perspectives+
According to the noninterface position, implicit and explicit L2 knowledge involve different acquisitional mechanisms ~Hulstijn, 2002; Krashen, 1981!, are stored in different parts of the brain ~Paradis, 1994!, and are accessed for performance by different processes, either automatic or controlled ~R+ Ellis, 1993!+ In its pure form, this position rejects both the possibility of explicit knowledge transforming directly into implicit knowledge and the possibility of implicit knowledge becoming explicit+ However, in a weaker form of the noninterface position, the possibility of implicit knowledge transforming into explicit is recognized through the process of conscious reflection on and analysis of output generated by means of implicit knowledge ~Bialystok, 1994!+
In contrast, the strong interface position claims that not only can explicit knowledge be derived from implicit knowledge but also that explicit knowl- edge can be converted into implicit knowledge through practice; that is, learn- ers can first learn a rule as a declarative fact and then, by dint of practice, can convert it into an implicit representation, although this need not entail the loss of the original explicit representation+ The interface position was first formally advanced by Sharwood Smith ~1981! and has subsequently been promoted by DeKeyser ~1998!+ Differences exist, however, regarding the nature of the practice that is required to effect the transformation from explicit to implicit knowledge; in particular, researchers disagree on whether this prac- tice can be mechanical or needs to be communicative in nature+
The weak interface position exists in three versions, all of which acknowl- edge the possibility of explicit knowledge becoming implicit but posit some limitation on when or how this can take place+ The first version posits that explicit knowledge can convert into implicit knowledge through practice only if the learner is developmentally ready to acquire the linguistic form ~R+ Ellis, 1993!+ This version draws on notions of learnability in accordance with attested developmental sequences in L2 acquisition ~e+g+, Pienemann, 1989!+ The sec- ond version holds that explicit knowledge contributes indirectly to the acqui- sition of implicit knowledge by promoting some of the processes believed to be responsible+ N+ Ellis ~1994!, for example, suggested that “declarative rules can have ‘top-down’ influences on perception” ~p+ 16!, in particular by making relevant features salient and thus enabling learners to notice them and to notice the gap between the input and their existing linguistic competence+ Finally, according to the third version, learners can use their explicit knowledge to produce output that then serves as auto-input to their implicit learning mech- anisms ~Schmidt & Frota, 1986; Sharwood Smith, 1981!+
Irrespective of the role played by explicit knowledge in the acquisition of implicit knowledge, there is wide acceptance that explicit knowledge can con- tribute to performance+ Krashen ~1977! argued that explicit knowledge is avail- able to the monitor, the production mechanism that enables learners to edit
Downloaded from https://www.cambridge.org/core. IP address: 182.209.114.22, on 10 Sep 2018 at 01:31:01, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1017/S0272263105050096

Measuring Implicit and Explicit Knowledge 145
their own performance by drawing on what they consciously know to be cor- rect+ Bialystok ~1982! showed that different performance tasks are likely to induce L2 learners to draw differentially on their implicit and explicit knowl- edge+ Fairly obviously, for example, she found that formal writing tasks are likely to induce learners to draw more extensively on their analyzed knowl- edge of an L2 than tasks calling for unplanned, oral communication+
These positions all have their adherents and have been the topic of much argument in the SLA literature+ However, they have not been subjected to empirical inquiry+ One reason for this is the lack of agreed instruments designed to ascertain the nature of knowledge acquired by learners: implicit, explicit, or some amalgam of the two+ To illustrate this problem, I will consider a num- ber of representative studies that have attempted to examine the relationship between learners’ implicit and explicit knowledge+