TY  - JOUR
A1  - Risse, Sarah
A1  - Hohenstein, Sven
A1  - Kliegl, Reinhold
A1  - Engbert, Ralf
T1  - A theoretical analysis of the perceptual span based on SWIFT simulations of the n+2 boundary paradigm
JF  - Visual cognition
N2  - Eye-movement experiments suggest that the perceptual span during reading is larger than the fixated word, asymmetric around the fixation position, and shrinks in size contingent on the foveal processing load. We used the SWIFT model of eye-movement control during reading to test these hypotheses and their implications under the assumption of graded parallel processing of all words inside the perceptual span. Specifically, we simulated reading in the boundary paradigm and analysed the effects of denying the model to have valid preview of a parafoveal word n + 2 two words to the right of fixation. Optimizing the model parameters for the valid preview condition only, we obtained span parameters with remarkably realistic estimates conforming to the empirical findings on the size of the perceptual span. More importantly, the SWIFT model generated parafoveal processing up to word n + 2 without fitting the model to such preview effects. Our results suggest that asymmetry and dynamic modulation are plausible properties of the perceptual span in a parallel word-processing model such as SWIFT. Moreover, they seem to guide the flexible distribution of processing resources during reading between foveal and parafoveal words.
KW  - Eye movements
KW  - Reading
KW  - Computational modelling
KW  - Perceptual span
KW  - Preview
Y1  - 2014
U6  - https://doi.org/10.1080/13506285.2014.881444
SN  - 1350-6285
SN  - 1464-0716
VL  - 22
IS  - 3-4
SP  - 283
EP  - 308
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Schad, Daniel
A1  - Engbert, Ralf
T1  - The zoom lens of attention simulating shuffled versus normal text reading using the SWIFT model
JF  - Visual cognition
N2  - Assumptions on the allocation of attention during reading are crucial for theoretical models of eye guidance. The zoom lens model of attention postulates that attentional deployment can vary from a sharp focus to a broad window. The model is closely related to the foveal load hypothesis, i.e., the assumption that the perceptual span is modulated by the difficulty of the fixated word. However, these important theoretical concepts for cognitive research have not been tested quantitatively in eye movement models. Here we show that the zoom lens model, implemented in the SWIFT model of saccade generation, captures many important patterns of eye movements. We compared the model's performance to experimental data from normal and shuffled text reading. Our results demonstrate that the zoom lens of attention might be an important concept for eye movement control in reading.
KW  - Computational modelling
KW  - Eye movements
KW  - Foveal load hypothesis
KW  - Perceptual span
KW  - Reading
KW  - Zoom lens model of attention
Y1  - 2012
U6  - https://doi.org/10.1080/13506285.2012.670143
SN  - 1350-6285
SN  - 1464-0716
VL  - 20
IS  - 4-5
SP  - 391
EP  - 421
PB  - Wiley
CY  - Hove
ER  -