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 - JOUR A1 - Krügel, André A1 - Rothkegel, Lars A1 - Engbert, Ralf T1 - No exception from Bayes’ rule BT - the presence and absence of the range effect for saccades explained JF - Journal of vision N2 - In an influential theoretical model, human sensorimotor control is achieved by a Bayesian decision process, which combines noisy sensory information and learned prior knowledge. A ubiquitous signature of prior knowledge and Bayesian integration in human perception and motor behavior is the frequently observed bias toward an average stimulus magnitude (i.e., a central-tendency bias, range effect, regression-to-the-mean effect). However, in the domain of eye movements, there is a recent controversy about the fundamental existence of a range effect in the saccadic system. Here we argue that the problem of the existence of a range effect is linked to the availability of prior knowledge for saccade control. We present results from two prosaccade experiments that both employ an informative prior structure (i.e., a nonuniform Gaussian distribution of saccade target distances). Our results demonstrate the validity of Bayesian integration in saccade control, which generates a range effect in saccades. According to Bayesian integration principles, the saccadic range effect depends on the availability of prior knowledge and varies in size as a function of the reliability of the prior and the sensory likelihood. KW - saccades KW - saccadic accuracy KW - range effect KW - Bayesian sensorimotor KW - integration KW - central-tendency bias Y1 - 2020 U6 - https://doi.org/10.1167/jov.20.7.15 SN - 1534-7362 VL - 20 IS - 7 PB - ARVO CY - Rockville 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 - JOUR A1 - Krügel, André A1 - Engbert, Ralf T1 - On the launch-site effect for skipped words during reading N2 - The launch-site effect, a systematic variation of within-word landing position as a function of launch-site distance, is among the most important oculomotor phenomena in reading. Here we show that the launch-site effect is strongly modulated in word skipping, a finding which is inconsistent with the view that the launch-site effect is caused by a saccadic-range error. We observe that distributions of landing positions in skipping saccades show an increased leftward shift compared to non-skipping saccades at equal launch-site distances. Using an improved algorithm for the estimation of mislocated fixations, we demonstrate the reliability of our results. Y1 - 2010 UR - http://www.sciencedirect.com/science/journal/00426989 U6 - https://doi.org/10.1016/j.visres.2010.05.009 SN - 0042-6989 ER -