Dynamics of phonological cognition

A fundamental problem in spoken language is the duality between the continuous aspects of phonetic performance and the discrete aspects of phonological competence. We study 2 instances of this problem from the phenomenon of voicing neutralization and vowel harmony. In each case, we present a model where the experimentally observed continuous distinctions are linked to the discreteness of phonological form using the mathematics of nonlinear dynamics.     

Evidence of proactive forefoot control during landings on inclined surfaces

The notion of proactive control of landings is generally accepted, and some underlying mechanisms have already been described. Only little is known on adjustments at the foot level, however. The authors therefore investigated the foot and ankle behavior of 24 participants as they landed on differently inclined surfaces. A 4-segment model of the foot and ankle provided 3-dimensional kinematics. They also analyzed activation patterns from several muscles and the ground reaction force. Participants anticipated the different surfaces, as shown by the forefoot kinematics and the activation patterns before touch down. Anticipation of the surface inclination led to adjustments in forefoot orientation and probably also in joint stiffness. The authors suggest that those adjustments tend to enhance the self-stabilizing potential of the mechanical system. The enhancement of that potential would ease the subsequent stabilization, reducing the demands on the neural system.     

The scope of linguistic generalizations: evidence from Hebrew word formation

Does the productive use of language stem from the manipulation of mental variables (e.g. "noun", "any consonant")? If linguistic constraints appeal to variables, rather than instances (e.g. "dog", "m"), then they should generalize to any representable novel instance, including instances that fall beyond the phonological space of a language. We test this prediction by investigating a constraint on the structure of Hebrew roots. Hebrew frequently exhibits geminates (e.g. ss) in its roots, but it strictly constraints their location: geminates are frequent at the end of the root (e.g. mss), but rare at its beginning (e.g. ssm). Symbolic accounts capture the ban on root-initial geminates as *XXY, where X and Y are variables that stand for any two distinct consonants. If the constraint on root structure appeals to the identity of abstract variables, then speakers should be able to extend it to root geminates with foreign phonemes, including phonemes with foreign feature values. We present findings from three experiments supporting this prediction. These results suggest that a complete account of linguistic processing must incorporate mechanisms for generalization outside the representational space of trained items. Mentally-represented variables would allow speakers to make such generalizations.     

Only the right noise? Effects of phonetic and visual input variability on 14‐month‐olds' minimal pair word learning

Seminal work by Werker and colleagues (Stager & Werker [1997] Nature, 388, 381–382) has found that 14‐month‐old infants do not show evidence for learning minimal pairs in the habituation‐switch paradigm. However, when multiple speakers produce the minimal pair in acoustically variable ways, infants' performance improves in comparison to a single speaker condition (Rost & McMurray [2009] Developmental Science, 12, 339–349). The current study further extends these results and assesses how different kinds of input variability affect 14‐month‐olds' minimal pair learning in the habituation‐switch paradigm testing German learning infants. The first two experiments investigated word learning when the labels were spoken by a single speaker versus when the labels were spoken by multiple speakers. In the third experiment we studied whether non‐acoustic variability, implemented by visual variability of the objects presented together with the labels, would also affect minimal pair learning. We found enhanced learning in the multiple speakers compared to the single speaker condition, confirming previous findings with English‐learning infants. In contrast, visual variability of the presented objects did not support learning. These findings both confirm and better delimit the beneficial role of speech‐specific variability in minimal pair learning. Finally, we review different proposals on the mechanisms via which variability confers benefits to learning and outline what may be likely principles that underlie this benefit. We highlight among these the multiplicity of acoustic cues signalling phonemic contrasts and the presence of relations among these cues. It is in these relations where we trace part of the source for the apparent paradoxical benefit of variability in learning.