  For all the poverty of the stimulus argument shows, the constraints  in question might indeed be language-specific and innate, but with  contents quite different from those proposed in current theories of  UG. Or, the constraints might be innate, but not language-specific.  For instance, as Tomasello 2003 argues, children's early linguistic  theorizing appears to be constrained by their inborn abilities to  share attention with others and to discern others' communicative  intentions. On his view, a child's early linguistic hypotheses are  based on the assumption that the person talking to him is attempting  to convey information about the thing(s) that they are both currently attending to. (Another example of an innate but non-language specific constraint on language learning derives from the structure of the  mammalian auditory system; ‘categorical perception,’ and  is relation to the acquisition of phonological knowledge is discussed below, §3.3.4.). Another alternative is that the constraints  might be learned, that is, derived from past experiences. An example  again comes from Tomasello (2003). He argues that  entrenchment, or the frequency with which a linguistic  element has been used with a certain communicative function, is an  important constraint on the development of children's later syntactic knowledge. For instance, it has been shown experimentally that the  more often a child hears an element used for a particular  communicative purpose, the less likely she is to extend that element  to new contexts. (See Tomasello 2003:179).