This simple example illustrates perhaps the most fundamental aspect of our perceptual experience of the world around us, viz. its spatial structure and temporal coherence. We are aware of unified objects and of their layout in three-dimensional space; temporally extended events unfold in a meaningful and generally predictable fashion. Yet the ease, immediacy and apparent simplicity with which we construct an organised world of objects and events belies the complexity of the mental computations and representations that support such experience and guide our actions. This conundrum of how the unity of perceptual experience can arise from the vagaries of proximal stimulation-of how constancies of object and event structure can obtain despite the spatial and temporal flux of sensory information-has led researchers since the time of Helmholtz ( 1866/ 1962) to propose that mental representations of objects and their relations in space and time are needed to organise and to integrate changing patterns of physical stimulation. This chapter addresses the growing body of current theory and research on the nature of the mental representations that support both our conscious awareness of visual objects and events, as well as actions directed towards them. I concentrate almost exclusively on the representation of visual objects; nonetheless, extending the framework developed here for understanding object representation to the analysis of visual events is an area of current experimental and theoretical activity in my laboratory.