Dr. Patti Adank (University College London)
The role of motor cortex in speech perception
Thursday, 31. May 2018, 16:15 to 18:00
Human motor circuits are active during speech perception. However, the precise conditions under which the motor system is active during speech perception are not clear. Two current accounts make distinct predictions for how listening to speech engages speech motor representations. The first account suggests that the motor system is most strongly activated when observing familiar actions while a second account asserts that motor excitability is greatest when observing less familiar, ambiguous actions. I will first discuss how we investigated these predictions using transcranial magnetic stimulation (TMS) by measuring Motor Evoked Potentials (MEPs) in lip and hand motor cortex. Second, I will discuss an experiment in which we aimed to further clarify the precise nature of activation of articulatory motor representations during speech perception. Firstly, it is unknown whether speech motor activity is preferentially engaged when perceiving forms of motor-based signal distortion (form dependent), or if motor activity is facilitated whenever perception is challenged, irrespective of the source of the difficulty (form independent). Third, it is unknown whether and how speech motor facilitation during speech perception is moderated by hearing ability, despite hearing sensitivity being paramount to understanding speech in challenging conditions. We investigated these questions in a final MEP experiment including younger and older listeners.
Prof. Dr. Geert Brône (KU Leuven)
Die Koordination von Blickverhalten in der Interaktion. Eine Eye-Tracking-Studie zu Feedback und Feedbackelizitierung in triadischen Gesprächen
Thursday, 12. April 2018, 16:15 to 18:00
Prof. Dr. Gerhard Jäger (Universität Tübingen)
Typologies in equilibrium
Thursday, 15. March 2018, 16:15 to 18:00
In a landmark paper, Maslova (2000) argued that the synchronous frequencies of a typological variable do not reveal distributional universals. As there is no guarantee that the underlying dynamic process has reached equilibrium, observed frequencies may
reflect properties of ancestor languages rather than functional tendencies. As a remedy, Maslova proposes to estimate the transition rates between types from diachronic data and to compute the equilibrium distribution analytically instead.
Probably due to the sparsity of diachronic typological evidence, this program has not been realized so far. Techniques from the *phylogenetic comparative method* (cf. Nunn, 2011) in computational biology, however, paired with the newly available electronic typological data sources, afford an alternative way to realized Maslova's goal.
Once a typological variable and a collection of languages has been fixed, the workflow is as follows:
1. Infer a (distribution of) phylogeny(ies) from lexical data.
2. Estimate the transition matrix between the values of the variable.
3. Calculate the equilibrium distribution of this Markov process.
I conducted two case studies: (A) The major word order types, using WALS, and (B) case marking alignment patterns, using the data from Bickel et al., 2014. In both studies, I used the ASJP database (Wichmann et al., 2016) for the first step.
In (B), we found substantial differences between equilibrium and observed values. The corresponding results for (A), however, suggest that equilibrium has been reached.