@article{SorensenGafos2016, author = {Sorensen, Tanner and Gafos, Adamantios I.}, title = {The Gesture as an Autonomous Nonlinear Dynamical System}, series = {Ecological psychology : a publication of the International Society for Ecological Psychology}, volume = {28}, journal = {Ecological psychology : a publication of the International Society for Ecological Psychology}, publisher = {Elsevier}, address = {Abingdon}, issn = {1040-7413}, doi = {10.1080/10407413.2016.1230368}, pages = {188 -- 215}, year = {2016}, abstract = {We propose a theory of how the speech gesture determines change in a functionally relevant variable of vocal tract state (e.g., constriction degree). A core postulate of the theory is that the gesture determines how the variable evolves in time independent of any executive timekeeper. That is, the theory involves intrinsic timing of speech gestures. We compare the theory against others in which an executive timekeeper determines change in vocal tract state. Theories that employ an executive timekeeper have been proposed to correct for disparities between theoretically predicted and experimentally observed velocity profiles. Such theories of extrinsic timing make the gesture a nonautonomous dynamical system. For a nonautonomous dynamical system, the change in state depends not just on the state but also on time. We show that this nonautonomous extension makes surprisingly weak kinematic predictions both qualitatively and quantitatively. We propose instead that the gesture is a theoretically simpler nonlinear autonomous dynamical system. For the proposed nonlinear autonomous dynamical system, the change in state depends nonlinearly on the state and does not depend on time. This new theory provides formal expression to the notion of intrinsic timing. Furthermore, it predicts experimentally observed relations among kinematic variables.}, language = {en} } @article{GibsonSotiropoulouTobinetal.2019, author = {Gibson, Mark and Sotiropoulou, Stavroula and Tobin, Stephen and Gafos, Adamantios I.}, title = {Temporal Aspects of Word Initial Single Consonants and Consonants in Clusters in Spanish}, series = {Phonetic}, volume = {76}, journal = {Phonetic}, number = {6}, publisher = {Karger}, address = {Basel}, issn = {0031-8388}, doi = {10.1159/000501508}, pages = {448 -- 478}, year = {2019}, abstract = {We examined gestural coordination in C1C2 (C1 stop, C2 lateral or tap) word initial clusters using articulatory (electromagnetic articulometry) and acoustic data from six speakers of Standard Peninsular Spanish. We report on patterns of voice onset time (VOT), gestural plateau duration of C1, C2, and their overlap. For VOT, as expected, place of articulation is a major factor, with velars exhibiting longer VOTs than labials. Regarding C1 plateau duration, voice and place effects were found such that voiced consonants are significantly shorter than voiceless consonants, and velars show longer duration than labials. For C2 plateau duration, lateral duration was found to vary as a function of onset complexity (C vs. CC). As for overlap, unlike in French, where articulatory data for clusters have also been examined, clusters where both C1 and C2 are voiced show more overlap than where voicing differs. Further, overlap was affected by the C2 such that clusters where C2 is a tap show less overlap than clusters where C2 is a lateral. We discuss these results in the context of work aiming to uncover phonetic (e.g., articulatory or perceptual) and phonological forces (e.g., syllabic organization) on timing.}, language = {en} } @article{TobinHullebusGafos2018, author = {Tobin, Stephen and Hullebus, Marc Antony and Gafos, Adamantios I.}, title = {Immediate phonetic convergence in a cue-distractor paradigm}, series = {The journal of the Acoustical Society of America}, volume = {144}, journal = {The journal of the Acoustical Society of America}, number = {6}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0001-4966}, doi = {10.1121/1.5082984}, pages = {EL528 -- EL534}, year = {2018}, abstract = {During a cue-distractor task, participants repeatedly produce syllables prompted by visual cues. Distractor syllables are presented to participants via headphones 150 ms after the visual cue (before any response). The task has been used to demonstrate perceptuomotor integration effects (perception effects on production): response times (RTs) speed up as the distractor shares more phonetic properties with the response. Here it is demonstrated that perceptuomotor integration is not limited to RTs. Voice Onset Times (VOTs) of the distractor syllables were systematically varied and their impact on responses was measured. Results demonstrate trial-specific convergence of response syllables to VOT values of distractor syllables.}, language = {en} } @article{TamasiMckeanGafosetal.2018, author = {Tamasi, Katalin and Mckean, Cristina and Gafos, Adamantios I. and H{\"o}hle, Barbara}, title = {Children's gradient sensitivity to phonological mismatch}, series = {Journal of child language}, volume = {46}, journal = {Journal of child language}, number = {1}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {0305-0009}, doi = {10.1017/S0305000918000259}, pages = {1 -- 23}, year = {2018}, abstract = {In a preferential looking paradigm, we studied how children's looking behavior and pupillary response were modulated by the degree of phonological mismatch between the correct label of a target referent and its manipulated form. We manipulated degree of mismatch by introducing one or more featural changes to the target label. Both looking behavior and pupillary response were sensitive to degree of mismatch, corroborating previous studies that found differential responses in one or the other measure. Using time-course analyses, we present for the first time results demonstrating full separability among conditions (detecting difference not only between one vs. more, but also between two and three featural changes). Furthermore, the correct labels and small featural changes were associated with stable target preference, while large featural changes were associated with oscillating looking behavior, suggesting significant shifts in looking preference over time. These findings further support and extend the notion that early words are represented in great detail, containing subphonemic information.}, language = {en} } @article{WilliamsEscuderoGafos2018, author = {Williams, Daniel Philip and Escudero, Paola and Gafos, Adamantios I.}, title = {Spectral change and duration as cues in Australian English listeners' front vowel categorization}, series = {The journal of the Acoustical Society of America}, volume = {144}, journal = {The journal of the Acoustical Society of America}, number = {3}, publisher = {American Institute of Physics}, address = {Melville}, issn = {0001-4966}, doi = {10.1121/1.5055019}, pages = {EL215 -- EL221}, year = {2018}, abstract = {Australian English /iː/, /ɪ/, and /ɪə/ exhibit almost identical average first (F1) and second (F2) formant frequencies and differ in duration and vowel inherent spectral change (VISC). The cues of duration, F1 × F2 trajectory direction (TD) and trajectory length (TL) were assessed in listeners' categorization of /iː/ and /ɪə/ compared to /ɪ/. Duration was important for distinguishing both /iː/ and /ɪə/ from /ɪ/. TD and TL were important for categorizing /iː/ versus /ɪ/, whereas only TL was important for /ɪə/ versus /ɪ/. Finally, listeners' use of duration and VISC was not mutually affected for either vowel compared to /ɪ/.}, language = {en} } @article{Gafos2019, author = {Gafos, Adamantios I.}, title = {Multistability in speech and other activities}, series = {Of trees and birds. A Festschrift for Gisbert Fanselow}, journal = {Of trees and birds. A Festschrift for Gisbert Fanselow}, publisher = {Universit{\"a}tsverlag Potsdam}, address = {Potsdam}, isbn = {978-3-86956-457-9}, doi = {10.25932/publishup-43258}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-432580}, pages = {343 -- 360}, year = {2019}, language = {en} } @article{ShawGafos2015, author = {Shaw, Jason A. and Gafos, Adamantios I.}, title = {Stochastic Time Models of Syllable Structure}, series = {PLoS one}, volume = {10}, journal = {PLoS one}, number = {5}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0124714}, pages = {36}, year = {2015}, abstract = {Drawing on phonology research within the generative linguistics tradition, stochastic methods, and notions from complex systems, we develop a modelling paradigm linking phonological structure, expressed in terms of syllables, to speech movement data acquired with 3D electromagnetic articulography and X-ray microbeam methods. The essential variable in the models is syllable structure. When mapped to discrete coordination topologies, syllabic organization imposes systematic patterns of variability on the temporal dynamics of speech articulation. We simulated these dynamics under different syllabic parses and evaluated simulations against experimental data from Arabic and English, two languages claimed to parse similar strings of segments into different syllabic structures. Model simulations replicated several key experimental results, including the fallibility of past phonetic heuristics for syllable structure, and exposed the range of conditions under which such heuristics remain valid. More importantly, the modelling approach consistently diagnosed syllable structure proving resilient to multiple sources of variability in experimental data including measurement variability, speaker variability, and contextual variability. Prospects for extensions of our modelling paradigm to acoustic data are also discussed.}, language = {en} } @article{GafosCharlowShawetal.2014, author = {Gafos, Adamantios I. and Charlow, Simon and Shaw, Jason A. and Hoole, Philip}, title = {Stochastic time analysis of syllable-referential intervals and simplex onsets}, series = {Journal of phonetics}, volume = {44}, journal = {Journal of phonetics}, publisher = {Elsevier}, address = {London}, issn = {0095-4470}, doi = {10.1016/j.wocn.2013.11.007}, pages = {152 -- 166}, year = {2014}, abstract = {We pursue an analysis of the relation between qualitative syllable parses and their quantitative phonetic consequences. To do this, we express the statistics of a symbolic organization corresponding to a syllable parse in terms of continuous phonetic parameters which quantify the timing of the consonants and vowels that make up syllables: consonantal plateau durations, vowel durations, and their variances. These parameters can be estimated from continuous phonetic data. This enables analysis of the link between symbolic phonological form and the continuous phonetics in which this form is manifest. Pursuing such an analysis, we illustrate the predictions of the syllabic organization corresponding to simplex onsets and derive a number of previously experimentally observed and simulation results. Specifically, we derive not only the canonical phonetic manifestations of simplex onsets but also the result that, under certain conditions we make precise, the phonetic indices of the simplex onset organization change to a range of values characteristic of the complex onset organization. Finally, we explore the behavior of phonetic indices for syllabic organization over progressively increasing,sizes of lexical samples, thereby concomitantly diversifying the phonetic context over which these indices are taken.}, language = {en} } @article{RoonGafos2015, author = {Roon, Kevin D. and Gafos, Adamantios I.}, title = {Perceptuo-motor effects of response-distractor compatibility in speech: beyond phonemic identity}, series = {Psychonomic bulletin \& review : a journal of the Psychonomic Society}, volume = {22}, journal = {Psychonomic bulletin \& review : a journal of the Psychonomic Society}, number = {1}, publisher = {Springer}, address = {New York}, issn = {1069-9384}, doi = {10.3758/s13423-014-0666-6}, pages = {242 -- 250}, year = {2015}, abstract = {Previous studies have found faster response times in a production task when a speaker perceives a distractor syllable that is identical to the syllable they are required to produce. No study has found such effects when a response and a distractor are not identical but share parameters below the level of the phoneme. Results from Experiment 1 show some evidence of a response-time effect of response-distractor voicing congruency. Experiment 2 showed a robust effect of articulator congruency: perceiving a distractor that has the same articulatory organ as that implicated in the planned motor response speeds up response times. These results necessitate a more direct and specific formulation of the perception-production link than warranted by previous experimental evidence. Implications for theories of speech production are also discussed.}, language = {en} } @article{HoehleFritzscheBollAvetisyanetal.2021, author = {H{\"o}hle, Barbara and Fritzsche, Tom and Boll-Avetisyan, Natalie and Hullebus, Marc and Gafos, Adamantios I.}, title = {Respect the surroundings}, series = {JASA Express Letters}, volume = {1}, journal = {JASA Express Letters}, number = {2}, publisher = {AIP Publ.}, address = {Melville}, issn = {2691-1191}, doi = {10.1121/10.0003574}, pages = {7}, year = {2021}, abstract = {Fourteen-month-olds' ability to distinguish a just learned word, /bu?k/, from its minimally different word, /du?k/, was assessed under two pre-exposure conditions: one where /b, d/-initial forms occurred in a varying vowel context and another where the vowel was fixed but the final consonant varied. Infants in the experiments benefited from the variable vowel but not from the variable final consonant context, suggesting that vowel variability but not all kinds of variability are beneficial. These results are discussed in the context of time-honored observations on the vowel-dependent nature of place of articulation cues for consonants.}, language = {en} }