@misc{RolfsEngbertKliegl2005, author = {Rolfs, Martin and Engbert, Ralf and Kliegl, Reinhold}, title = {Crossmodal coupling of oculomotor controland spatial attention in vision and audition}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56804}, year = {2005}, abstract = {Fixational eye movements occur involuntarily during visual fixation of stationary scenes. The fastest components of these miniature eye movements are microsaccades, which can be observed about once per second. Recent studies demonstrated that microsaccades are linked to covert shifts of visual attention [e.g., Engbert \& Kliegl (2003), Vision Res 43:1035-1045]. Here,we generalized this finding in two ways. First, we used peripheral cues, rather than the centrally presented cues of earlier studies. Second, we spatially cued attention in vision and audition to visual and auditory targets. An analysis of microsaccade responses revealed an equivalent impact of visual and auditory cues on microsaccade-rate signature (i.e., an initial inhibition followed by an overshoot and a final return to the pre-cue baseline rate). With visual cues or visual targets,microsaccades were briefly aligned with cue direction and then opposite to cue direction during the overshoot epoch, probably as a result of an inhibition of an automatic saccade to the peripheral cue. With left auditory cues and auditory targets microsaccades oriented in cue direction. Thus, microsaccades can be used to study crossmodal integration of sensory information and to map the time course of saccade preparation during covert shifts of visual and auditory attention.}, language = {en} } @misc{KlieglEngbert2007, author = {Kliegl, Reinhold and Engbert, Ralf}, title = {Conference Abstracts: 14th European Conference on Eye Movements ECEM2007}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-56799}, year = {2007}, language = {de} } @unpublished{GuastiEngbertKrampeetal.2000, author = {Guasti, Giovanna and Engbert, Ralf and Krampe, Ralf T. and Kurths, J{\"u}rgen}, title = {Phase transitions, complexity, and stationarity in the production of polyrhythms}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14933}, year = {2000}, abstract = {Contents: 1 Introduction 2 Experiment 3 Data 4 Symbolic dynamics 4.1 Symbolic dynamics as a tool for data analysis 4.2 2-symbols coding 4.3 3-symbols coding 5 Measures of complexity 5.1 Word statistics 5.2 Shannon entropy 6 Testing for stationarity 6.1 Stationarity 6.2 Time series of cycle durations 6.3 Chi-square test 7 Control parameters in the production of rhythms 8 Analysis of relative phases 9 Discussion 10 Outlook}, language = {en} } @unpublished{EngbertScheffczykKrampeetal.1997, author = {Engbert, Ralf and Scheffczyk, Christian and Krampe, Ralf-Thomas and Rosenblum, Mikhael and Kurths, J{\"u}rgen and Kliegl, Reinhold}, title = {Tempo-induced transitions in polyrhythmic hand movements}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14380}, year = {1997}, abstract = {We investigate the cognitive control in polyrhythmic hand movements as a model paradigm for bimanual coordination. Using a symbolic coding of the recorded time series, we demonstrate the existence of qualitative transitions induced by experimental manipulation of the tempo. A nonlinear model with delayed feedback control is proposed, which accounts for these dynamical transitions in terms of bifurcations resulting from variation of the external control parameter. Furthermore, it is shown that transitions can also be observed due to fluctuations in the timing control level. We conclude that the complexity of coordinated bimanual movements results from interactions between nonlinear control mechanisms with delayed feedback and stochastic timing components.}, language = {en} } @phdthesis{Engbert1997, author = {Engbert, Ralf}, title = {Nichtlineare Dynamik kognitiv-motorischer Prozesse}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0000157}, school = {Universit{\"a}t Potsdam}, year = {1997}, abstract = {Die Produktion von Polyrhythmen ist ein wichtiger experimenteller Zugang f{\"u}r die Untersuchung der menschlichen Motorik. Durch Variation des Tempos (externer Kontrollparameter) bei rhythmischen Bewegungsabl{\"a}ufen k{\"o}nnen qualitative {\"U}berg{\"a}nge in der Koordinationsdynamik induziert werden. Diese {\"U}berg{\"a}nge lassen sich mit der Methode der symbolischen Dynamik in experimentellen Zeitreihen nachweisen und sind ein wichtiger Hinweis darauf, dass die untersuchten Bewegungsabl{\"a}ufe nichtlinearen Kontrollprozessen unterliegen. Die theoretische Beschreibung bimanueller Rhythmusproduktion mit gekoppelten Differenzengleichungen f{\"u}hrt auf ein Modell mit nichtlinearer Fehlerkontrolle. Es ist eine wichtige Eigenschaft der Kontrollprozesse, dass sie mit zeitverz{\"o}gerter R{\"u}ckkopplung arbeiten. Neben deterministischen Steuerungsmechanismen ist die Motorik des Menschen ausserdem von Fluktuationen auf zwei Ebenen gekennzeichnet, der kognitiven Kontrollebene und der Ebene der motorischen Systeme. Daher ist die Koordination von Bewegungen das Ergebnis von Wechselwirkungen zwischen nichtlinearen, zeitverz{\"o}gerten Kontrollprozessen und stochastischen Fluktuationen.}, language = {de} }