“…It has long been observed that nested sentence structures like (1) are very dif cult to understand (Bever, 1970;Cowper, 1976;Gibson, 1991Gibson, , 1998Kimball, 1973;Lewis, 1993Lewis, , 1996Miller & Isard, 1964;Stabler, 1994 A syntactic category, A, is said to be nested (or centre-embedded) within another category B if B contains A, a constituent to the left of A, and a constituent to the right of A. In (1), the relative clause (RC) ''who the nurse .…”