Linguistics seeks to understand and explain the real world phenomenon of human language. It does so by making observations and formulating hypotheses about linguistic processes. It is the empirical test of such hypotheses that we refer to as experimental linguistics. If linguistics is to be regarded as an empirical science, its theories of human language must be subject to empirical verification. Such theory-testing requires the accumulation of reliable, researcher-independent language facts. The goal of Experimental Linguistics is to further the simultaneous progress of data accumulation and theory verification. We stress the simultaneity because of the problems inherent in the independent pursuit of either. Linguistic theories are of limited interest for explaining human language if they cannot be subjected to empirical verification. On the other hand, although linguistic data may be of intrinsic interest, their chief value to the discipline is as evidence for theories.