TY  - JOUR
A1  - Engbert, Ralf
A1  - Krampe, Ralf-Thomas
A1  - Kliegl, Reinhold
T1  - Synchronizing movements with the metronome : nonlinear error corrections and unstable periodic orbits
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Engbert, Ralf
A1  - Scheffczyk, Christian
A1  - Krampe, Ralf-Thomas
A1  - Kurths, Jürgen
A1  - Kliegl, Reinhold
T1  - Symbolic dynamics of bimanual production of polyrhythms
N2  - We analyse time series from a study on bimanual rhythmic movements in which the speed of performance (the external control parameter) was experimentally manipulated. Using symbolic transformations as a visualization technique we observe qualitative changes in the dynamics of the timing patterns. Such phase transitions are quantitatively described by measures of complexity. Using these results we develop an advanced symbolic coding which enables us to detect important dynamical structures. Furthermore, our analysis raises new questions concerning the modelling of the underlying human cognitive-motor system.
Y1  - 2002
SN  - 3-540- 63481-9
ER  - 
TY  - INPR
A1  - Engbert, Ralf
A1  - Scheffczyk, Christian
A1  - Krampe, Ralf-Thomas
A1  - Rosenblum, Mikhael
A1  - Kurths, Jürgen
A1  - Kliegl, Reinhold
T1  - Tempo-induced transitions in polyrhythmic hand movements
N2  - 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.
T3  - NLD Preprints - 41 
Y1  - 1997
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14380
ER  - 
TY  - INPR
A1  - Guasti, Giovanna
A1  - Engbert, Ralf
A1  - Krampe, Ralf T.
A1  - Kurths, Jürgen
T1  - Phase transitions, complexity, and stationarity in the production of polyrhythms
N2  - 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
T3  - NLD Preprints - 57 
Y1  - 2000
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-14933
ER  - 
TY  - JOUR
A1  - Kliegl, Reinhold
A1  - Krampe, Ralf-Thomas
A1  - Mayr, Ulrich
T1  - Formal models of age differences in task complexity effects
Y1  - 2003
ER  - 
TY  - GEN
A1  - Kliegl, Reinhold
A1  - Mayr, Ulrich
A1  - Krampe, Ralf
T1  - Time-accuracy functions for determining process and person differences : an application to cognitive aging
N2  - A paradigm for the determination of time-accuracy functions (TAFs) for individual participants is introduced for two pairs of tasks differing in cognitive complexity, that is, word scanning vs cued recognition and figural scanning vs figural reasoning. TAFs can be used to test dissociations of cognitive processes beyond scale-related ambiguities of ordinal interactions. The approach is applied to examine the cognitive-aging hypothesis that a single slowing factor can account for interactions between adult age and cognitive task complexity. Twenty young and 20 old adults participated in 17 sessions. Presentation times required for 75, 87.5, and 100% accuracies were determined for each task with a variant of the psychophysical method of limits. Accuracy was fit by negatively accelerated functions of presentation time. State-trace analyses showed that different slowing factors are required for high- and low-complexity tasks. Relations to speed-accuracy and performance-resource functions are discussed.
T3  - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - paper 166 
Y1  - 1994
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-17101
ER  - 
TY  - JOUR
A1  - Kliegl, Reinhold
A1  - Mayr, Ulrich
A1  - Krampe, Ralf T.
T1  - Psychophysikalische Bestimmung von kognitiven Darbietungenszeit-Leistungs-Funktionen
Y1  - 1993
ER  - 
TY  - JOUR
A1  - Kliegl, Reinhold
A1  - Mayr, Ulrich
A1  - Krampe, Ralf-Thomas
T1  - Process dissociations in cognitive aging
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Kliegl, Reinhold
A1  - Mayr, Ulrich
A1  - Krampe, Ralf-Thomas
T1  - Time-accuracy functions for the determination of person and process differences : an application to cognitive aging
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Kliegl, Reinhold
A1  - Mayr, Ulrich
A1  - Krampe, Ralf-Thomas
T1  - Prozessdissoziationen in der kognitiven Altersforschung
Y1  - 1998
SN  - 3-8017-0761-X
ER  -