Callen’s artist practice seeks to serve as an embodiment of an experience in the present moment. The current moment is our only opportunity for experience, poised between memories of the past and projections of the future; his paintings are an exploration of visual representation of this specific state of mind. As he paints he deliberately intends to minimize the clutter of preconceived expectations and instead focus on the immediacy of the moment. Colours, composition, texture and movement are applied on canvas, driven by the natural and often unpredictable behaviour of the selected materials and processes as they intersect by intuitive actions during the formative moment. Acceleration, both centripetal and gravitational, is used to manipulate the paint on the canvas through the use of shaped canvases, a unique spinning machine and various pendulum devices.

Callen’s practice has expanded to include perforative and process oriented elements as well. In 2011 Callen began doing his spin and pendulum paintings live in certain settings. By engaging individuals in the process of creating and experiencing an artwork Callen seeks to inspire us to experience own present moment.