Infant sensitivity to distributional information can affect phonetic discrimination.

For nearly two decades it has been known that infants' perception of speech sounds is affected by native language input during the first year of life. However, definitive evidence of a mechanism to explain these developmental changes in speech perception has remained elusive. The present study provides the first evidence for such a mechanism, showing that the statistical distribution of phonetic variation in the speech signal influences whether 6- and 8-month-old infants discriminate a pair of speech sounds. We familiarized infants with speech sounds from a phonetic continuum, exhibiting either a bimodal or unimodal frequency distribution. During the test phase, only infants in the bimodal condition discriminated tokens from the endpoints of the continuum. These results demonstrate that infants are sensitive to the statistical distribution of speech sounds in the input language, and that this sensitivity influences speech perception.     

Is Internalism About Knowledge Consistent with Content Externalism?

There is widespread suspicion that there is a principled conflict between epistemic internalism and content externalism (or anti-individualism). Despite the prominence of this suspicion, it has rarely been substantiated by explicit arguments. However, Duncan Pritchard and Jesper Kallestrup have recently provided a prima facie argument concluding that internalism about knowledge and externalism about content are incompatible. I criticize the incompatibilist argument and conclude that the purported incompatibility is, at best, prima facie. This is, in part, because several steps in the argument are faulty and, in part, because there are promising responses available to the compatibilists.

The role of prior experience in language acquisition

Learners exposed to an artificial language recognize its abstract structural regularities when instantiated in a novel vocabulary (e.g., Gómez, Gerken, & Schvaneveldt, 2000; Tunney & Altmann, 2001). We asked whether such sensitivity accelerates subsequent learning, and enables acquisition of more complex structure. In Experiment 1, pre-exposure to a category-induction language of the form aX bY sped subsequent learning when the language is instantiated in a different vocabulary. In Experiment 2, while naíve learners did not acquire an acX bcY language, in which aX and bY co-occurrence regularities were separated by a c-element, prior experience with an aX bY language provided some benefit. In Experiment 3 we replicated this finding with a 24-hour delay between learning phases, and controlled for prior experience with the aX bY language's prosodic and phonological characteristics. These findings suggest that learners, and the structure they can acquire, change as a function of experience.     

Discursive justification and skepticism

In this paper, I consider how a general epistemic norm of action that I have proposed in earlier work should be specified in order to govern certain types of acts: assertive speech acts. More specifically, I argue that the epistemic norm of assertion is structurally similar to the epistemic norm of action. First, I argue that the notion of warrant operative in the epistemic norm of a central type of assertion is an internalist one that I call ??discursive justification.?? This type of warrant is internalist insofar as it requires that the agent is capable of articulating reasons for her belief. The idea, roughly, is that when one asserts that p, one is supposed to be in a position to give reasons for believing that p. Bonjour??s reliable clairvoyant Norman, for example, is not in an epistemic position to make assertions regarding the president??s whereabouts??even if Norman knows the president??s whereabouts. In conclusion, I briefly consider whether a type of skeptical argument??often labeled Agrippa??s Trilemma??is motivated, at least in part, by the fact that responses to it violate the relevant epistemic norm of assertion.