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Abstract

How does the brain discriminate between different actions? Action recognition has been an active field of research for long time, still little is known about how the representations of different actions in the brain are related to each other. We wanted to find out whether different actions were ordered according to their semantic meaning or kinematic motion by employing a novel visual action adaptation paradigm. A total of 24 participants rated four different social actions in terms of their perceived differences in either semantic meaning or kinematic motion. Then, the specific perceptual bias for each action was determined by measuring the size of the action adaptation aftereffect in each participant. Finally, the meaning and motion ratings were used to predict the measured adaptation aftereffect for each action using linear regression. Semantic meaning and the interaction of meaning and motion significantly predicted the adaptation aftereffects, but kinematic motion alone was not a significant predictor. These results imply that differences between distinct actions are rather encoded in terms of their meaning than motion in the brain. The current experimental paradigm could be a useful method for further mapping the relationship between different actions in the human brain.