## Overview

*i*Map4 is an open source Matlab toolbox for the statistical fixation mapping of eye movement data, implementing a user-friendly interface that provides straightforward, easy to interpret statistical graphical outputs. *i*Map4 matches the standards of the robust statistical analysis implemented in neuroimaging techniques (M/EEG, fMRI). *i*Map4 applies univariate, pixel-wise Linear Mixed Models (LMM) on the smoothed fixation maps with each subject as one of the random effects, which offers the flexibility to code for multiple between- and within- subject comparisons. Users can perform all possible linear contrasts for the fixed effects (main effects, interactions, etc.). Importantly, it implements non-parametric statistics based on resampling. We developed a novel spatial cluster test based on bootstrapping to assess the statistical significance of the linear contrasts. We hope that *i*Map4 could provide an easy access to the routine use of robust data-driven analyses in spatial fixation mappings.

The methodological details of the spatial mapping using Linear Mixed Models and the resampling algorithm, as well as the validation of statistics implemented in *i*Map4 are provided in a peer reviewed paper (currently under review). For a general thoughtful introduction to mixed models, users of the toolbox should refer to Raudenbush & Bryk (2002), McCulloch, Searle & Neuhaus (2011), and Christensen (2011). We recommend *i*Map4 users also read Baayen, Davidson & Bates (2008) and Bolker et al., (2009) for some examples on how to perform and report mixed model analysis.