Impact of semantic similarity in novel associations: Direct and indirect routes to action.

Actions produced in response to familiar objects are predominantly mediated by the visual structure of objects, and less so by their semantic associations. Choosing an action in response to an object tends to be faster than choosing the object's name, leading to the suggestion that there are direct links between the visual representations of objects and their actions. The relative contribution of semantics, however, is unclear when actions are produced in response to novel objects. To investigate the role of semantics when object-action associations are novel, we had participants learn to use and name novel objects and rehearse the object, action, and name associations over one week. Each object-action pair was associated with a label that was either semantically similar or semantically distinct. We found that semantic similarity only affected action and name production when the object associations were novel, suggesting that semantic information is recruited when actions are produced in response to novel objects. We also observed that the advantage to producing an action was absent when associations were novel, suggesting that practice is necessary for these direct links to develop.