Modelling the distraction task using the LBA and neural covariates
Our ability to focus on a task whilst remaining sensitive to unexpected changes in the environment is vital to goal-directed behaviour. The distraction task has been widely used in cognitive neurosciences, especially in people with schizophrenia, to study performance impairments when the environment changes. In the distraction paradigm, participants perform an active task requiring simple responses while task-irrelevant changes occur occasionally. In the current study, the distraction paradigm featured a simple auditory tone duration judgment task with occasional (irrelevant) changes in the tone frequency. In the original study (Schroger & Wolff, 1998) these ‘deviant’ trials were associated with a distraction effect (slower and more error-prone responding). Simultaneous EEG recording of event-related responses to the sequence of tones has linked the distraction effect to key response components known as the mismatch-negativity (MMN) occurring ~150ms after the deviance onset and the subsequent P300 peaking around 250-350ms. In the present study, we compared several evidence accumulation models of behavioural response times in the distraction paradigm. These linear ballistic accumulator (LBA) models could vary across threshold and drift rates for a variety of conditional combinations. Following this we incorporated EEG recordings to inform the drift rate parameter in a directed joint model approach. As expected, the free model provided the best descriptive adequacy of the data, however, the directed model did capture variance in the data. This is promising as the directed model allows EEG measurements to inform the model by linking latent variables to observable phenomenon.