Visual perception of mean relative phase and phase variability.

Abstract

Perception of relative phase and phase variability may play a fundamental role in interlimb coordination. This study was designed to investigate the perception of relative phase and of phase variability and the stability of perception in each case. Observers judged the relative phasing of two circles rhythmically moving on a computer display. The circles moved from side to side, simulating movement in the frontoparallel plane, or increased and decreased in size, simulating movement in depth. Under each viewing condition, participants observed the same displays but were to judge either mean relative phase or phase variability. Phase variability interfered with the mean-relative-phase judgments, in particular when the mean relative phase was 0°. Judgments of phase variability varied as a function of mean relative phase. Furthermore, the stability of the judgments followed an asymmetric inverted U-shaped relation with mean relative phase, as predicted by the Haken-Kelso-Bunz model.In the early eighties, Kugler, Turvey, and Kelso, among others, introduced the concepts of nonlinear dynamics into the study of human movement, thereby building on Bernstein's (1967) important insight that perception-action systems should be regarded as coordinative structures that are task specific and soft molded (Kelso, Holt, Rubin, & Kugler, 1981;Kugler, Kelso, & Turvey, 1980;Kugler & Turvey, 1987). Taking rhythmicity as paradigmatic of human movement, they noted that cyclical movements are sustained in spite of the universal tendency for order to diminish and cease as described by the second law of thermodynamics (cf. Yates, 1982). They suggested therefore that coordinative structures are best studied as ensembles of nonlinear coupled oscillators, exhibiting limit-cycle properties (Kugler et al., 1980;Turvey, 1990). The energy for sustaining cyclical motion was hypothesized to be regulated using information in an autonomous fashion. Indeed, cyclical limb movement has been shown to exhibit limitcycle properties, and coordinated rhythmic limb movement has been modeled successfully as a system of coupled nonlinear oscillators (e.g., see Haken, Kelso, & Bunz, 1985;Kay, Kelso, Saltzman, & Schoner, 1987;Kelso et al., 1981). As a result of these developments, dynamic systems theory has had an enormous impact on human movement science (for reviews, see Beek, Peper, & Stegeman, 1995;Haken, 1996;Kelso, 1995 We thank Betty Tuller and Claudia Carello for helpful comments on an earlier version of this article.Correspondence concerning this article should be addressed to Frank T. J. M. Zaal, who is now at the Faculty of Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081 BT Amsterdam, the Netherlands. Electronic mail may be sent to fzaal@fbw.vu.nl. Schoner, 1990;Schmidt & Turvey, 1995;Turvey, 1990). However, a brief review of this research reveals that the perceptual variables used in coordinated limb movement are not yet well understood, although the prominent role of perceptual information is widely recognized. Coordinat...

The integration of temporally shifted visual feedback in a synchronization task: The role of perceptual stability in a visuo-proprioceptive conflict situation

“…As hypothesized, the results generally confirmed the findings of previous research that clearly showed that accuracy and variability evolve monotonically between the different coordination modes (Buekers et al, 2000;Swinnen, Jardin, Meulenbroek, Dounskaia, & Hofkens-Van Den Brandt, 1997;Zaal et al, 2000). Specifically, the best synchronization performance was observed in the in-phase synchronization mode while the anti-phase mode involved significant performance loss.…”

“…These studies highlighted the role of perception in the rhythmic movement coordination since the coupling was visually mediated by the ability to detect the information used to couple and coordinate the oscillating limbs (Wilson, Collins, & Bingham, 2005a, 2005b. Moreover, the stability of the perception of two oscillating visual signals was found to vary as an asymmetric U-function of mean relative phase (i.e., dependent on the directional compatibility between the oscillating signals) (Bingham, Schmidt, & Zaal, 1999;Bingham, Zaal, Shull, & Collins, 2001;Zaal, Bingham, & Schmidt, 2000). In fact, non-0° phase relations between the two oscillating visual signal were judged to be intrinsically more variable than 0°, maximally so at 90°, with 180° phase relation judged to be intermediate between these performance extremes at 0° and ACCEPTED MANUSCRIPT Synchronization 4 90°.…”

Proprioceptive Perception of Phase Variability.

“…First, we intended to replicate the signal used in Zaal et al (2000), in which there was no Phase ϫ Phase Variability interaction. Did we actually make the manipulandum move in this fashion?…”

“…Bingham, Schmidt, and Zaal (1999) replicated these results by using oscillators driven by actual human movement. Zaal, Bingham, and Schmidt (2000) used dots oscillating in both the fronto-parallel plane and in depth, and showed that the levels of phase variability were discriminated best at 0°, then 180°, and not at all at 90°.The overall pattern of the judgments, then, is an asymmetric inverted U-shaped function, with 90°judged to be inherently noisy and 180°to be noisier than 0°, and in response to an increase in frequency 180°was judged to be increasingly noisy whereas 0°w as unaffected. This pattern mirrors three characteristic phenomena from the movement coordination literature.…”

“…Bingham, Schmidt, and Zaal (1999) replicated these results by using oscillators driven by actual human movement. Zaal, Bingham, and Schmidt (2000) used dots oscillating in both the fronto-parallel plane and in depth, and showed that the levels of phase variability were discriminated best at 0°, then 180°, and not at all at 90°.…”