Modern linguistics research has two problems: 1) intuitional judgements are not always clear and do not always match the subtle predictions made by theory, and 2) the distinction between semantics and syntax becomes increasingly obscure. Acquisition data has traditionally been seen as undermined by "performance" factors, but the results of twenty years of research has revealed that acquisition data can be as subtle as intuitional data. Now the question arises: can acquisition data offer unique insights into linguistic ability. Two factors suggest that this is possible: 1) the time course of acquisition can reveal which factors belong together, and 2) the large amount of data, drawn from responses to contextually natural stories allows us to see effects that may be beyond any kind of sharp intuition. In this paper, we reveal some acquisition data on the effect of negative islands on long distance WH movements. The experiment we developed was set to examine the theory of barriers on WH movement. In particular, the revised version of barriers as it is described in Relativized Minimality (Rizzi, 1990).