@article{RisseHohensteinKliegletal.2014,
  author    = {Risse, Sarah and Hohenstein, Sven and Kliegl, Reinhold and Engbert, Ralf},
  title     = {A theoretical analysis of the perceptual span based on SWIFT simulations of the n+2 boundary paradigm},
  series = {Visual cognition},
  volume    = {22},
  journal   = {Visual cognition},
  number    = {3-4},
  publisher = {Routledge, Taylor \& Francis Group},
  address   = {Abingdon},
  issn      = {1350-6285},
  doi       = {10.1080/13506285.2014.881444},
  pages     = {283 -- 308},
  year      = {2014},
  abstract  = {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.},
  language  = {en}
}
@article{MeybergSinnEngbertetal.2017,
  author    = {Meyberg, Susann and Sinn, Petra and Engbert, Ralf and Sommer, Werner},
  title     = {Revising the link between microsaccades and the spatial cueing of voluntary attention},
  series = {Vision research : an international journal for functional aspects of vision.},
  volume    = {133},
  journal   = {Vision research : an international journal for functional aspects of vision.},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0042-6989},
  doi       = {10.1016/j.visres.2017.01.001},
  pages     = {47 -- 60},
  year      = {2017},
  abstract  = {Microsaccades - i.e., small fixational saccades generated in the superior colliculus (SC) - have been linked to spatial attention. While maintaining fixation, voluntary shifts of covert attention toward peripheral targets result in a sequence of attention-aligned and attention-opposing microsaccades. In most previous studies the direction of the voluntary shift is signaled by a spatial cue (e.g., a leftwards pointing arrow) that presents the most informative part of the cue (e.g., the arrowhead) in the to-be attended visual field. Here we directly investigated the influence of cue position and tested the hypothesis that microsaccades align with cue position rather than with the attention shift. In a spatial cueing task, we presented the task-relevant part of a symmetric cue either in the to-be attended visual field or in the opposite field. As a result, microsaccades were still weakly related to the covert attention shift; however, they were strongly related to the position of the cue even if that required a movement opposite to the cued attention shift. Moreover, if microsaccades aligned with cue position, we observed stronger cueing effects on manual response times. Our interpretation of the data is supported by numerical simulations of a computational model of microsaccade generation that is based on SC properties, where we explain our findings by separate attentional mechanisms for cue localization and the cued attention shift. We conclude that during cueing of voluntary attention, microsaccades are related to both - the overt attentional selection of the task-relevant part of the cue stimulus and the subsequent covert attention shift.(C) 2017 Elsevier Ltd. All rights reserved.},
  language  = {en}
}
@article{SchadEngbert2012,
  author    = {Schad, Daniel and Engbert, Ralf},
  title     = {The zoom lens of attention simulating shuffled versus normal text reading using the SWIFT model},
  series = {Visual cognition},
  volume    = {20},
  journal   = {Visual cognition},
  number    = {4-5},
  publisher = {Wiley},
  address   = {Hove},
  issn      = {1350-6285},
  doi       = {10.1080/13506285.2012.670143},
  pages     = {391 -- 421},
  year      = {2012},
  abstract  = {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.},
  language  = {en}
}