TY - JOUR A1 - Rabe, Maximilian Michael A1 - Chandra, Johan A1 - Krügel, André A1 - Seelig, Stefan A. A1 - Vasishth, Shravan A1 - Engbert, Ralf T1 - A bayesian approach to dynamical modeling of eye-movement control in reading of normal, mirrored, and scrambled texts JF - Psychological Review N2 - In eye-movement control during reading, advanced process-oriented models have been developed to reproduce behavioral data. So far, model complexity and large numbers of model parameters prevented rigorous statistical inference and modeling of interindividual differences. Here we propose a Bayesian approach to both problems for one representative computational model of sentence reading (SWIFT; Engbert et al., Psychological Review, 112, 2005, pp. 777-813). We used experimental data from 36 subjects who read the text in a normal and one of four manipulated text layouts (e.g., mirrored and scrambled letters). The SWIFT model was fitted to subjects and experimental conditions individually to investigate between- subject variability. Based on posterior distributions of model parameters, fixation probabilities and durations are reliably recovered from simulated data and reproduced for withheld empirical data, at both the experimental condition and subject levels. A subsequent statistical analysis of model parameters across reading conditions generates model-driven explanations for observable effects between conditions. KW - reading eye movements KW - dynamical models KW - Bayesian inference KW - oculomotor KW - control KW - individual differences Y1 - 2021 U6 - https://doi.org/10.1037/rev0000268 SN - 0033-295X SN - 1939-1471 VL - 128 IS - 5 SP - 803 EP - 823 PB - American Psychological Association CY - Washington ER - TY - JOUR A1 - Chandra, Johan A1 - Krügel, André A1 - Engbert, Ralf T1 - Modulation of oculomotor control during reading of mirrored and inverted texts JF - Scientific Reports N2 - The interplay between cognitive and oculomotor processes during reading can be explored when the spatial layout of text deviates from the typical display. In this study, we investigate various eye-movement measures during reading of text with experimentally manipulated layout (word-wise and letter-wise mirrored-reversed text as well as inverted and scrambled text). While typical findings (e.g., longer mean fixation times, shorter mean saccades lengths) in reading manipulated texts compared to normal texts were reported in earlier work, little is known about changes of oculomotor targeting observed in within-word landing positions under the above text layouts. Here we carry out precise analyses of landing positions and find substantial changes in the so-called launch-site effect in addition to the expected overall slow-down of reading performance. Specifically, during reading of our manipulated text conditions with reversed letter order (against overall reading direction), we find a reduced launch-site effect, while in all other manipulated text conditions, we observe an increased launch-site effect. Our results clearly indicate that the oculomotor system is highly adaptive when confronted with unusual reading conditions. KW - human behaviour KW - psychology KW - eye-movement control KW - e-z reader KW - ideal-observer model KW - fixation locations KW - landing positions KW - saccade generation KW - cognitive-control KW - dynamical model KW - decision-theory KW - attention Y1 - 2019 U6 - https://doi.org/10.1038/s41598-020-60833-6 SN - 2045-2322 VL - 10 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - GEN A1 - Chandra, Johan A1 - Krügel, André A1 - Engbert, Ralf T1 - Modulation of oculomotor control during reading of mirrored and inverted texts T2 - Postprints der Universität Potsdam : Humanwissenschaftliche Reihe N2 - The interplay between cognitive and oculomotor processes during reading can be explored when the spatial layout of text deviates from the typical display. In this study, we investigate various eye-movement measures during reading of text with experimentally manipulated layout (word-wise and letter-wise mirrored-reversed text as well as inverted and scrambled text). While typical findings (e.g., longer mean fixation times, shorter mean saccades lengths) in reading manipulated texts compared to normal texts were reported in earlier work, little is known about changes of oculomotor targeting observed in within-word landing positions under the above text layouts. Here we carry out precise analyses of landing positions and find substantial changes in the so-called launch-site effect in addition to the expected overall slow-down of reading performance. Specifically, during reading of our manipulated text conditions with reversed letter order (against overall reading direction), we find a reduced launch-site effect, while in all other manipulated text conditions, we observe an increased launch-site effect. Our results clearly indicate that the oculomotor system is highly adaptive when confronted with unusual reading conditions. T3 - Zweitveröffentlichungen der Universität Potsdam : Humanwissenschaftliche Reihe - 659 KW - human behaviour KW - psychology KW - eye-movement control KW - e-z reader KW - ideal-observer model KW - fixation locations KW - landing positions KW - saccade generation KW - cognitive-control KW - dynamical model KW - decision-theory KW - attention Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-494879 SN - 1866-8364 IS - 659 ER - TY - JOUR A1 - Chandra, Johan A1 - Krügel, André A1 - Engbert, Ralf T1 - Experimental test of Bayesian saccade targeting under reversed reading direction JF - Attention, Perception, & Psychophysics N2 - During reading, rapid eye movements (saccades) shift the reader's line of sight from one word to another for high-acuity visual information processing. While experimental data and theoretical models show that readers aim at word centers, the eye-movement (oculomotor) accuracy is low compared to other tasks. As a consequence, distributions of saccadic landing positions indicate large (i) random errors and (ii) systematic over- and undershoot of word centers, which additionally depend on saccade lengths (McConkie et al.Visual Research, 28(10), 1107-1118,1988). Here we show that both error components can be simultaneously reduced by reading texts from right to left in German language (N= 32). We used our experimental data to test a Bayesian model of saccade planning. First, experimental data are consistent with the model. Second, the model makes specific predictions of the effects of the precision of prior and (sensory) likelihood. Our results suggest that it is a more precise sensory likelihood that can explain the reduction of both random and systematic error components. KW - eye movements and reading KW - Bayesian modeling KW - eye-movement control KW - model KW - fixation KW - attention KW - words KW - swift Y1 - 2019 U6 - https://doi.org/10.3758/s13414-019-01814-4 SN - 1943-393X SN - 1943-3921 VL - 82 SP - 1230 EP - 1240 PB - Springer CY - New York, NY ER - TY - THES A1 - Chandra, Johan T1 - The role of the oculomotor control in eye movements during reading N2 - Most reading theories assume that readers aim at word centers for optimal information processing. During reading, saccade targeting turns out to be imprecise: Saccades’ initial landing positions often miss the word centers and have high variance, with an additional systematic error that is modulated by the distance from the launch site to the center of the target word. The performance of the oculomotor system, as reflected in the statistics of within-word landing positions, turns out to be very robust and mostly affected by the spatial information during reading. Hence, it is assumed that the saccade generation is highly automated. The main goal of this thesis is to explore the performance of the oculomotor system under various reading conditions where orthographic information and the reading direction were manipulated. Additionally, the challenges in understanding the eye movement data to represent the oculomotor process during reading are addressed. Two experimental studies and one simulation study were conducted for this thesis, which resulted in the following main findings: (i) Reading texts with orthographic manipulations leads to specific changes in the eye movement patterns, both in temporal and spatial measures. The findings indicate that the oculomotor control of eye movements during reading is dependent on reading conditions (Chapter 2 & 3). (ii) Saccades’ accuracy and precision can be simultaneously modulated under reversed reading condition, supporting the assumption that the random and systematic oculomotor errors are not independent. By assuming that readers increase the precision of sensory observation while maintaining the learned prior knowledge when reading direction was reversed, a process-oriented Bayesian model for saccade targeting can account for the simultaneous reduction of oculomotor errors (Chapter 2). (iii) Plausible parameter values serving as proxies for the intended within-word landing positions can be estimated by using the maximum a posteriori estimator from Bayesian inference. Using the mean value of all observations as proxies is insufficient for studies focusing on the launch-site effect because the method exhibits the strongest bias when estimating the size of the effect. Mislocated fixations remain a challenge for the currently known estimation methods, especially when the systematic oculomotor error is large (Chapter 4). The results reported in this thesis highlight the role of the oculomotor system, together with underlying cognitive processes, in eye movements during reading. The modulation of oculomotor control can be captured through a precise analysis of landing positions. N2 - Zahlreiche Theorien des Lesens gehen davon aus, dass Sakkaden beim Lesen auf die Wortmitte abzielen, um eine optimale Informationsverarbeitung zu erreichen. Die Lan- depositionen von Sakkaden verfehlen oft die Wortmitte und weisen eine hohe Varianz auf, mit einem zusätzlichen systematischen Fehler, der durch die Entfernung zwischen der Sakkadensstartposition und der Position der Wortmitte moduliert wird. Das Verhalten der Okulomotorik, wie es sich in der Statistik der Sakkadenlandepositionen widerspiegelt, erweist sich als sehr robust und wird hauptsächlich von räumlichen Informationen beeinflusst. Daher wird angenommen, dass der Sakkadengenerierungprozess automatisiert ist. Das Hauptziel dieser Dissertation ist es, das Verhalten des okulomotorischen Systems unter verschiedenen Lesebedingungen zu untersuchen. Hierzu wurden orthographische Informationen und die Leserichtung manipuliert. Blickbewegungsdaten repräsentieren den okulomotorischen Prozess beim Lesen. Die Herausforderungen beim Verständnis dieser Daten wurden thematisiert. Insgesamt wurden zwei experimentelle Studien und eine Simulationsstudie durchgeführt, die zu folgenden Hauptergebnissen führen: (i) Die Blickbewegungsmuster beim Lesen von Texten mit manipulierter Orthographie veränderten sich spezifisch zur jeweiligen Bedingung, sowohl in zeitlichen als auch räumlichen Kennwerten der Blickbewegungsdaten. Dies legt nahe, dass die okulomotorische Kontrolle beim Lesen an die Manipulation anpasst (Kapitel 2 & 3). (ii) Sowohl Genauigkeit, als auch Präzision von Sakkaden lassen sich durch die veränderte Leserichtung verbessern. Das Ergebnis zeigt, dass systematische und zufällige Fehler des okulomotorischen Systems nicht unabhängig sind. Das Bayes’sche Model zur Sakkadenplanung kann die empirischen Ergebnisse approximieren und zeitgleich die verbesserte Sakkadenausrichtung erklären. In der Rechts-nach-Links Lesebedingung verbessert sich die Präzision von sensorischen Informationen, während das a priori erlernte Vorwissen unverändert bleibt (Kapitel 2). (iii) Plausible Parameterwerte, die als Annäherung für intendierte Landepositionen dienen, können durch Verwendung des maximalen a posteriori Schätzers aus der Bayes’schen Inferenz geschätzt werden. Die einfache Mittelwertsmethode weist die stärksten Verzerrung bei der Schätzung der Effektstärke des Launch-Site-Effekts auf. Daher ist sie nicht ausreichend um den Effekt zu beschreiben. Falsch verorterte Fixationen bleiben eine Herausforderung für die derzeit bekannten Schätzmethoden, insbesondere wenn der systematische okulomotorische Fehler groß ist (Kapitel 4). Die in dieser Arbeit berichteten Ergebnisse unterstreichen die Rolle des okulomotorischen Systems, zusammen mit den zugrundeliegenden kognitiven Prozessen, bei der Blicksteuerung beim Lesen. Die Modulation der okulomotorischen Steuerung kann durch die genauen Analysen der Sakkadenlandepositionen erfasst werden. T2 - Die Rolle der Okulomotorik in Blickbewegungen beim Lesen KW - Oculomotor control KW - Eye movements KW - Reading KW - Blickbewegungen KW - Okulomotorik KW - Lesen Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-475930 ER -