Attentional modulation along the object-recognition pathway of the cortical visual system of primates has been shown to consist of enhanced representation of the retinal input at a specific location in space, or of objects located anywhere in the visual field which possess a critical object feature. Moreover, selective attention mechanisms allow the visual system to resolve competition among multiple objects in a crowded scene in favor of the object that is relevant for the current behavior. Finally, selective attention affects the spontaneous activity of neurons as well as their visually driven responses, and it does so not only by modulating the spiking activity of individual neurons, but also by modulating the degree of coherent firing within the critical neuronal populations. WIREs Cogni Sci 2011 2 392-407 DOI: 10.1002/wcs.117 For further resources related to this article, please visit the WIREs website.