Analysing reaction time distributions can provide insights into decision-making processes in the brain. The Linear Approach to Threshold with Ergodic Rate (LATER) model is arguably the simplest model for predicting reaction time distributions and can summarise distributions with as few as two free parameters. However, the coordinates for visualising and fitting distributions using LATER ("reciprobit" space) are irregular, making the application of this simple model inaccessible to those without a programming background. Here we describe an open-source R package - LATERmodel - that allows for easy visualisation of reaction time distributions, along with fitting of these using the LATER model. Using canonical data from the literature, we show our tool replicates key features from previous LATER analysis tools, whilst also providing more robust fitting procedures and a more flexible method for fitting sub-populations of very rapid, early responses. Whilst all features of LATERmodel can be used directly in the statistical programming language R, key features are also available through a RShiny graphical user interface to allow researchers without programming background to apply the LATER model to their reaction time data.
Keywords: decision making; latency; modelling; reaction time; saccade.