Nonword repetition in children and adults: effects on movement coordination

Hearing and repeating novel phonetic sequences, or novel nonwords, is a task that taps many levels of processing, including auditory decoding, phonological processing, working memory, speech motor planning and execution. Investigations of nonword repetition abilities have been framed within models of psycholinguistic processing, while the motor aspects, which also are critical for task performance, have been largely ignored. We focused our investigation on both the behavioral and speech motor performance characteristics of this task as performed in a learning paradigm by 9‐ and 10‐year‐old children and young adults. Behavioral (percent correct productions) and kinematic (movement duration, lip aperture variability – an index of the consistency of inter‐articulator coordination on repeated trials) measures were obtained in order to investigate the short‐term (Day 1, first five vs. next five trials) and longer‐term (Day 1 vs. Day 2, first five vs. next five trials) changes associated with practice within and between sessions. Overall, as expected, young adults showed higher levels of behavioral accuracy and greater levels of coordinative consistency than the children. Both groups, however, showed a learning effect, such that in general, later Day 1 trials and Day 2 trials were shorter in duration and more consistent in coordination patterns than Day 1 early trials. Phonemic complexity of the nonwords had a profound effect on both the behavioral and speech motor aspects of performance. The children showed marked learning effects on all nonwords that they could produce accurately, while adults’ performance improved only when challenged by the more complex nonword stimuli in the set. The findings point to a critical role for speech motor processes within models of nonword repetition and suggest that young adults, similar to children, show short‐ and longer‐term improvements in coordinative consistency with repeated production of complex nonwords. There is also a clear developmental change in nonword production performance, such that less complex novel sequences elicit changes in speech motor performance in children, but not in adults.     

Dewey and Rawls on Education

In this paper I compare the roles that the explicit and implicit educational theories of John Dewey and John Rawls play in their political works to show that Rawls’s approach is skeletal and inappropriate for defenders of democracy. I also uphold Dewey’s belief that education is valuable in itself, not only derivatively, contra Rawls. Next, I address worries for any educational theory concerning problems of distributive justice. Finally, I defend Dewey’s commitment to democracy as a consequence of the demands of productive public inquiry and education.

Efficiently checking propositional refutations in HOL theorem provers

This paper describes the integration of zChaff and MiniSat, currently two leading SAT solvers, with Higher Order Logic (HOL) theorem provers. Both SAT solvers generate resolution-style proofs for (instances of) propositional tautologies. These proofs are verified by the theorem provers. The presented approach significantly improves the provers' performance on propositional problems, and exhibits counterexamples for unprovable conjectures. It is also shown that LCF-style theorem provers can serve as viable proof checkers even for large SAT problems. An efficient representation of the propositional problem in the theorem prover turns out to be crucial; several possible solutions are discussed.     

Detection and recognition of auditory patterns

The detection/recognition theorem (Starr, Metz, Lusted, & Goodenough, 1975) provides a signal detection theory prediction of an observer's ability to identify one of a set of possible signals on the basis of the observer's ability to detect whether any signal is presented. The present findings show that the theorem can be applied to complex auditory stimuli in a fashion that is not merely a trivial extension of the results obtained with simple auditory stimuli.