Predictive Impact of Contextual Objects during Action Observation: Evidence from Functional Magnetic Resonance Imaging

The processing of congruent stimuli, such as an object or action in its typical location, is usually associated with reduced neural activity, probably due to facilitated recognition. However, in some situations, congruency increases neural activity-for example, when objects next to observed actions are likely versus unlikely to be involved in forthcoming action steps. Here, we investigated using fMRI whether the processing of contextual cues during action perception is driven by their (in)congruency and, thus, informative value to make sense of an observed scene. Specifically, we tested whether both highly congruent contextual objects (COs), which strongly indicate a future action step, and highly incongruent COs, which require updating predictions about possible forthcoming action steps, provide more anticipatory information about the action course than moderately congruent COs. In line with our hypothesis that especially the inferior frontal gyrus (IFG) subserves the integration of the additional information into the predictive model of the action, we found highly congruent and incongruent COs to increase bilateral activity in action observation nodes, that is, the IFG, the occipitotemporal cortex, and the intraparietal sulcus. Intriguingly, BA 47 was significantly stronger engaged for incongruent COs reflecting the updating of prediction in response to conflicting information. Our findings imply that the IFG reflects the informative impact of COs on observed actions by using contextual information to supply and update the currently operating predictive model. In the case of an incongruent CO, this model has to be reconsidered and extended toward a new overarching action goal.