Undergraduate Honors Theses

Date of Award

Spring 4-7-2017



First Advisor

Kaitlin Laidlaw

Second Advisor

Jody Culham


The present study investigated whether social aptitude is related to the effects of social intention on reach-to-grasp actions. Reach-to-grasp actions performed with social intentions (e.g. reaching to pick up a coffee cup to give to a friend) are characterized by different kinematic patterns than those performed with nonsocial intentions (e.g. reaching to pick up a coffee cup to move it aside). These intention-based kinematic changes are thought to serve a communicative function, allowing co-actors to better predict and respond to actions that are relevant to them. If this is true, then individuals who rate themselves as strong communicators should show better discrimination between social and nonsocial actions, whereas those who have poor communication skills should perform actions that are not as clearly differentiated based on social intentionality. In the present study, participants picked up and moved a block to the center of the table to either be collected by another person (social Give condition), or not (nonsocial Place condition). Although the required motor sequence was the same in both conditions, results indicate that actions with social (Give) intentions were associated with different kinematic patterns than actions with nonsocial (Place) intentions. Further, the degree to which certain action kinematics differed based on social intentionality was correlated with participants’ self- reported communication skills. The results are discussed in terms of how social interactions may benefit from communicating social intentionality through action. Future directions for extending beyond the conclusions of the present findings will also be discussed.