  Knowledge workers such as healthcare information professionals, legal
researchers, and librarians need to create and execute search strategies that
are comprehensive, transparent, and reproducible. The traditional solution is
to use proprietary query building tools provided by literature database
vendors. In the majority of cases, these query builders are designed using a
form-based paradigm that requires the user to enter keywords and ontology terms
on a line-by-line basis and then combine them using Boolean operators. However,
recent years have witnessed significant changes in human-computer interaction
technologies and users can now engage with online information systems using a
variety of novel data visualisation techniques. In this paper, we evaluate a
new approach to query building in which users express concepts as objects on a
visual canvas and compare this with traditional form-based query building in a
lab-based user study. The results demonstrate the potential of visual
interfaces to mitigate some of the shortcomings associated with form-based
interfaces and encourage more exploratory search behaviour. They also
demonstrate the value of having a temporary 'scratch' space in query
formulation. In addition, the findings highlight an ongoing need for
transparency and reproducibility in professional search and raise further
questions around how these properties may best be supported.
