TY - JOUR A1 - Meyberg, Susann A1 - Sinn, Petra A1 - Engbert, Ralf A1 - Sommer, Werner T1 - Revising the link between microsaccades and the spatial cueing of voluntary attention JF - Vision research : an international journal for functional aspects of vision. N2 - 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. KW - Endogenous attention KW - Visual search KW - Fixational eye movements KW - Posner cueing KW - Superior colliculus KW - Computational modelling Y1 - 2017 U6 - https://doi.org/10.1016/j.visres.2017.01.001 SN - 0042-6989 SN - 1878-5646 VL - 133 SP - 47 EP - 60 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Grimm, Volker A1 - Berger, Uta T1 - Robustness analysis: Deconstructing computational models for ecological theory and applications JF - Ecological modelling : international journal on ecological modelling and engineering and systems ecolog N2 - The design of computational models is path-dependent: the choices made in each step during model development constrain the choices that are available in the subsequent steps. The actual path of model development can be extremely different, even for the same system, because the path depends on the question addressed, the availability of data, and the consideration of specific expert knowledge, in addition to the experience, background, and modelling preferences of the modellers. Thus, insights from different models are practically impossible to integrate, which hinders the development of general theory. We therefore suggest augmenting the current culture of communicating models as working just fine with a culture of presenting analyses in which we try to break models, i.e., model mechanisms explaining certain observations break down. We refer to the systematic attempts to break a model as “robustness analysis” (RA). RA is the systematic deconstruction of a model by forcefully changing the model's parameters, structure, and representation of processes. We discuss the nature and elements of RA and provide brief examples. RA cannot be completely formalized into specific techniques and instead corresponds to detective work that is driven by general questions and specific hypotheses, with strong attention focused on unusual behaviours. Both individual modellers and ecological modelling in general will benefit from RA because RA helps with understanding models and identifying “robust theories”, which are general principles that are independent of the idiosyncrasies of specific models. Integrating the results of RAs from different models to address certain systems or questions will then provide a comprehensive overview of when certain mechanisms control system behaviour and when and why this control ceases. This approach can provide insights into the mechanisms that lead to regime shifts in actual ecological systems. KW - Sensitivity analysis KW - Ecological theory KW - Computational modelling KW - Robustness KW - Model analysis KW - Understanding Y1 - 2016 U6 - https://doi.org/10.1016/j.ecolmodel.2015.07.018 SN - 0304-3800 SN - 1872-7026 VL - 326 SP - 162 EP - 167 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Logacev, Pavel A1 - Vasishth, Shravan T1 - Understanding underspecification: A comparison of two computational implementations JF - The quarterly journal of experimental psychology N2 - Swets et al. (2008. Underspecification of syntactic ambiguities: Evidence from self-paced reading. Memory and Cognition, 36(1), 201–216) presented evidence that the so-called ambiguity advantage [Traxler et al. (1998 Traxler, M. J., Pickering, M. J., & Clifton, C. (1998). Adjunct attachment is not a form of lexical ambiguity resolution. Journal of Memory and Language, 39(4), 558–592. doi: 10.1006/jmla.1998.2600[CrossRef], [Web of Science ®], [Google Scholar]). Adjunct attachment is not a form of lexical ambiguity resolution. Journal of Memory and Language, 39(4), 558–592], which has been explained in terms of the Unrestricted Race Model, can equally well be explained by assuming underspecification in ambiguous conditions driven by task-demands. Specifically, if comprehension questions require that ambiguities be resolved, the parser tends to make an attachment: when questions are about superficial aspects of the target sentence, readers tend to pursue an underspecification strategy. It is reasonable to assume that individual differences in strategy will play a significant role in the application of such strategies, so that studying average behaviour may not be informative. In order to study the predictions of the good-enough processing theory, we implemented two versions of underspecification: the partial specification model (PSM), which is an implementation of the Swets et al. proposal, and a more parsimonious version, the non-specification model (NSM). We evaluate the relative fit of these two kinds of underspecification to Swets et al.’s data; as a baseline, we also fitted three models that assume no underspecification. We find that a model without underspecification provides a somewhat better fit than both underspecification models, while the NSM model provides a better fit than the PSM. We interpret the results as lack of unambiguous evidence in favour of underspecification; however, given that there is considerable existing evidence for good-enough processing in the literature, it is reasonable to assume that some underspecification might occur. Under this assumption, the results can be interpreted as tentative evidence for NSM over PSM. More generally, our work provides a method for choosing between models of real-time processes in sentence comprehension that make qualitative predictions about the relationship between several dependent variables. We believe that sentence processing research will greatly benefit from a wider use of such methods. KW - Computational modelling KW - Underspecification KW - Shallow processing Y1 - 2016 U6 - https://doi.org/10.1080/17470218.2015.1134602 SN - 1747-0218 SN - 1747-0226 VL - 69 SP - 996 EP - 1012 PB - BioMed Central CY - Abingdon ER - 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 -