27.06.2017 12:03

Heiko Schütt will give a talk at ECEM in Wuppertal which takes place from 20.-24.08.2017

Title: "Likelihood-based Parameter Estimation and Comparison of Dynamical Eye" by Heiko H. Schütt, Lars O. M. Rothkegel, Hans A. Trukenbrod, Sebastian Reich, Felix A. Wichmann & Ralf Engbert

Heiko Schütt


Recently, eye movement models aim to predict full scanpaths instead of fixation densities only. Therefore, parameter estimation, model analysis and comparison of such models are now of essential importance. We propose a likelihood based approach for model analysis in a fully dynamical framework that includes time-ordered experimental data and illustrate its use for the recent SceneWalk model. First we show that we can directly compute a likelihood for any model, which predicts a distribution for the next fixation given the previous ones. Computing a likelihood makes the full range of mathematical statistics available for such models. Namely we can perform Frequentist and Bayesian parameter estimation, which additionally provides credible intervals informing us how well which parameters are constrained by the data. Using hierarchical models inference is even possible for individual observers, which allows us to fit individual differences in saccade lengths with the model. Furthermore, our likelihood approach can be used to compare different models. In our example, the dynamical framework is shown to outperform non-dynamical models. Additionally, the likelihood based evaluation differentiates model variants, which produced indistinguishable predictions on hitherto used statistics. Our results indicate that the likelihood approach is a promising framework for models of full scanpaths.

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