Introducing the kollaR package: a user friendly open access solution for eye tracking analysis and visualization

Eye tracking has become an increasingly important tool in cognitive and developmental research, providing insights into processes that are difficult to measure otherwise. The majority of eye tracking studies depend on accurate identification of fixations and saccades in the recorded raw data through fixation filters. Subsequently, it is common to analyze whether fixations or saccades fall into specific areas of interest (AOI). The choice of algorithms can significantly influence study outcomes, especially in populations with noisy data such as young children or individuals with neurodevelopmental conditions. It is therefore crucial to compare and validate potential fixation filter algorithms as part of the eye tracking analysis. Here, we introduce the kollaR package, an open-source R library for performing the main steps of an eye tracking analysis from event detection, to AOI based analyses and visualizations of individual or group-level data for publications. The kollaR package was specifically designed to facilitate selection and validation of fixation filter algorithms through visualizations. In a validation analysis, we show that results from fixation filtering in kollaR is consistent with the output from Tobii Pro Lab, a commercially available software. Through the use of real data from typically developed controls and participants with Fragile X syndrome and intellectual disability, we demonstrate the use of kollaR to evaluate fixation filters and identify potential threats to data validity.