Figure 1.
Illustration of articulatory coordination and sequencing.
(A) onset consonantal gestures are precisely coordinated with the vocalic gesture and overlap substantially. (B) coda consonantal gestures are selected sequentially. Arrows show movement onsets. Gestural scores aligned to movement trajectories are shown for consonantal and vocalic gestures.
Figure 2.
Coupled oscillators model of coordination for CV (/pa/), CCV (/spa/), and VC (/ap/) forms.
For each form, a coupling graph is shown with in-phase coupling (solid green lines) and anti-phase coupling (dashed red lines). Oscillator phases proceed counter-clockwise until they reach an arbitrary phase value that triggers movement initiation, i.e. activation of the corresponding gesture in a gestural score.
Figure 3.
Competitive selection model dynamics.
(A) competitive selection of three units. (B) competitive selection of four units, with movement initiation delayed relative to (A). (C) Sequencing error in which unit 3 is selected early.
Figure 4.
Schematic illustration of effects of spin-coupling and activation coupling.
Spin-coupling forces act to decrease or increase the phase difference between oscillatory systems. Activation-coupling forces act mutually to increase or decrease activation.
Figure 5.
Activation potential functions and corresponding vector fields from three stages of articulatory production: (A) prior to response intention, (B) after response intention before selection, (C) after selection.
Composite (black lines) and component functions (colored lines) are shown.
Figure 6.
Examples of activation and spin coupling graphs.
Attractive/excitatory coupling relations solid lines) and repulsive/inhibitory coupling relations (dashed lines) are shown. (A) monosyllables; (B) multisyllabic and multi-word responses.
Figure 7.
Simulations of onset/coda asymmetry and complex onsets/codas.
(A) a CVC form “pot”. (B) a CCVCC form “spots”. Top rows of panels show potential functions and phases from a sequence of five stages in the planning of the utterance. Bottom rows of panels show activation variables and gestural driving functions.
Figure 8.
Dependence of RT on the activation potential gain (cx) and initial activation (x0).
Bold line shows prepared-response RT = 180 ms, dashed lines show corresponding range of ΔRT = [150, 250] for a given value of cx.
Figure 9.
Dependence of RT on the number of words (utterance length) and the number of syllables per word (word complexity).
The magnitudes of length and complexity effects are comparable in model simulations (squares) and empirical results (circles).
Table 1.
Comparison of the standard coupled oscillators model and the activation-spin model in accounting for onset/coda asymmetries.