TRoPICALS: A Computational Embodied Neuroscience Model of Experiments on Compatibility Effects.

Recent evidence shows that perceiving objects automatically activates the representation of their affordances. For example, the experiments on compatibility effects show that the reaction time needed to categorise an object by producing a certain hand grip is faster if the requested response is compatible with the affordance elicited by the size of the object (e.g., a small or a large grip). The article presents a neural-network architecture that provides a general framework to account for this kind of effects. The model was designed with a methodological approach that aims to provide increasingly general accounts of brain and behaviour (the approach uses four sources of constraints: neuroscientific data, behavioural data, functioning within embodied systems, and reproduction of learning processes). The model is based on four principles of brain organisation that underlie most compatibility effects. First, visual perception and action are organised in the brain along a dorsal neural pathway, which encodes affordances, and a ventral pathway, which encodes goals. Second, the prefrontal cortex within the ventral pathway gives a top-down bias to action selection by integrating information on stimuli, context, and goals. Third, reaction times depend on dynamic neural competitions for action selection, which integrate bottom-up and top-down sources of information. The congruence/incongruence between the information related to affordances and current goals explains the different reaction times found in the experiments. Fourth, because words referring to objects trigger "internal simulations" of their referents, they can cause compatibility effects similarly to objects. We validated the model by reproducing and explaining three types of compatibility effects and showed its heuristic power by producing two testable predictions. We also assessed the explicative power of the model on the basis of a critical comparison with related models and showed how it could be extended to account for other compatibility effects by relying on the aforementioned four principles.