The goal of this work is to measure the degree to which communication through gestures in virtual environments helps or hinders collaborative work on spatial tasks. People often gesture when they talk to each other about spatial concepts; in response to this behavior, many virtual collaboration tools have been created over the years to augment distance collaborations with gestures (see “Related Work”). However, relatively little work has been done do assess whether the addition of gestures actually improves collaboration, and in if so how does it help them? This work begins the exploration of these questions so as to better inform the design of future virtual collaboration tools. We explored these questions by performing controlled laboratory experiments. To do so, we developed an experimental test bed, Collabora-table, in which we could control the communication modes available to pairs of participants while they interacted in a 2D virtual space to complete shared tasks. Participants were asked to use three different interfaces, face-to-face, virtual sketching, and virtual sketching with hand images. The latter was found to reduce workload to levels indistinguishable from face-to-face interactions for conceptual product design tasks. However the effect appears to be sensitive to the task, and the implementation of the interfaces. Gestures may be an important communication channel to support in future tools to support virtual product design.Copyright © 2013 by ASME