The ability to perceive three-dimensional objects is a fundamental aspect of typical human vision, yet how the visual system utilises monocular cues to create three-dimensional objects from two-dimensional retinal input remains largely unexplored. We explore this question in the context of shape from shading, referring to the perception of a three-dimensional shape due to the shading pattern of an object. Shape from shading has previously been described as a pre-attentive process that occurs in parallel across the visual field. However, recent research has challenged this notion, suggesting that shape from shading involves two distinct processes. Specifically, an early stage that is responsible for object segregation from the background, operating in a pre-attentive manner, and a later stage which utilises top-down attention to identify three-dimensional shape. To investigate this proposal, we measure event-related potentials whilst participants passively or actively view three-dimensional or two-dimensional objects. It is predicted that passively viewing three-dimensional objects will significantly affect early event-related potentials (P1/N1) compared to passively viewing a two-dimensional control stimulus. In contrast, active, rather than passive viewing of three-dimensional objects, will significantly modulate later event-related potentials (P2/N2). Moreover, the difference in event-related potentials between passive and active viewing conditions will be greater for three-dimensional than two-dimensional objects, suggesting that the modulation of event-related potentials is due in part to three-dimensional processing, and not due to attentional effects alone. This study will aid in providing insight into the underlying cognitive processes that are required to perceive three-dimensional objects.