Mixing Habits and Planning for Multi-Step Target Reaching Using Arbitrated Predictive Actor-Critic
Farzaneh S. Fard, Thomas P. Trappenberg · 2018
Internal models are important when agents make decisions based on predictions of future states and their utilities. However, using internal models for planning can be time consuming. Therefore, it can be useful to use a habitual system for repetitive tasks that can be executed faster and with reduced algorithmic resources. Current evidence suggests that the brain uses both control systems, planning and habitual systems for behavioural control, which then requires an arbitration between these two systems. In our previous work [1], we proposed an Arbitrated Predictive Actor-Critic (APAC), which is a neural architecture demonstrating cooperative mechanisms of planning and habitual control systems for one step mapping. The present study tests the ability of such a model to control a simulated two-joints robotic arm during multiple reaching tasks with movement limitations that require multiple steps to solve the task. Our results show that APAC can learn the multi-step learning under various conditions. Interestingly, the APAC tends to shift from planning to habits by taking actions predicted by a habitual controller over the training time.