pinning down the concept of "interface" in bilingualism

since a finer differ- entiation among different types of interface are necessary. Are there structures that involve only putations? The testability of the hypothesis depends on demonstrating that such structures are immune from optionality effects and on the definition of ‘narrow syntax’. Recall that the IH was proposed for the highest possible level of ultimate at- tainment in L2. At first sight, the ‘interface vs narrow syntax’ distinction seems to capture some characteristics of L2 ultimate attainment in near-native speakers that had been reported in previous research. Coppieters’s (1987) seminal study of near-nativeness, for example, described larger native/near-native differences with respect to structures that involved semantic interpretation, but less noticeable