Task set has been shown to determine some important cognitive operations like conscious perception [Rafal, R. D., Ward, R., & Danziger, S. (2006). Selection for action and selection for awareness: Evidence from hemispatial neglect. Brain Research, 1080(1), 2-8], and the exogenous orienting of spatial attention [Folk, C. L., Remington, R. W., & Johnston, J. C. (1992). Involuntary covert orienting is contingent on attentional control settings. Journal of Experimental Psychology: Human Perception and Performance, 18(4), 1030-1044; Lupiáñez, J., Ruz, M., Funes, M. J., & Milliken, B. (2007). The manifestation of attentional capture: Facilitation or IOR depending on task demands. Psychological Research, 71(1), 77-91]. In the present study we investigate whether endogenous attention would also be task-dependent. We use an illusion of movement, the illusory line motion [Hikosaka, O., Miyauchi, S., & Shimojo, S. (1993). Focal visual attention produces illusory temporal order and motion sensation. Vision Research, 33(9), 1219-1240] to explore this question. Our results revealed that endogenously attending to detect the appearance of a target produce different consequences in modulating the illusion of movement than endogenously attending to discriminate one of its features. We suggest that endogenous attention is implemented differently depending on the task at hand, producing different effects on perceptual integration.