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  - 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  -