Effects of Decision Complexity in Goal-seeking Gridworlds: A Comparison of Instance-Based Learning and Reinforcement Learning Agents

Decisions under uncertainty are often made by weighing the expected costs and benefits of the available options. The tradeoffs of costs and benefits make some decisions easy and some difficult, particularly given uncertainty of these costs and rewards. In this research, we evaluate how a cognitive model based on Instance-Based Learning Theory (IBLT) and two well-known reinforcement learning (RL) algorithms learn to make better choices in a goal-seeking gridworld task under uncertainty and on increasing degrees of decision complexity. We also use a random agent as a base level comparison. Our results suggest that IBL and RL models are comparable in their accuracy levels on simple settings, but the RL models are more efficient than the IBL model. However, as decision complexity increases, the IBL model is not only more accurate but also more efficient than the RL models. Our results suggest that the IBL model is able to pursue highly rewarding targets even when the costs increase; while the RL models seem to get "distracted" by lower costs, reaching lower reward targets.