Experimental evidence from extraction for the D-shell analysis of clausal prolepsis

In clausal prolepsis constructions, a CP is ‘doubled’ by a pronoun in argument position (‘I love it that there are handouts’). We bring new experimental evidence to bear on long-standing questions about the structure of clausal prolepsis (Postal and Pullum 1988; Rothstein 1995). In three judgment studies, we show that clausal prolepsis constructions exhibit stronger island effects than baseline factive complements. We argue that this follows on an analysis where the proleptic pronoun and CP form an underlying DP constituent (Rosenbaum 1967; Angelopoulos 2025, among others). On this analysis, clausal prolepsis constructions are definite DP islands, which we corroborate with independent evidence from an understudied variant of clausal prolepsis in English that deploys a demonstrative (‘That sucks that there are no handouts’).