The debate between hierarchical versus sequential structure in language acquisition has recently flared up again (cf. Frank, Bod & Christiansen 2012; Pesetsky 2013). Roughly, the nativist view on language endorses that human language acquisition is guided by innate rules that operate on hierarchical structures. The empiricist view assumes that language acquisition is the product of abstractions from empirical input but leaves it as an open question whether sequential or hierarchical structure is needed. Some empirical models use sequential structure (e.g. Reali & Christiansen 2005) while other models are based on hierarchical structure (Bod 2009; Bod & Smets 2012).