The present study shows that an abrupt onset cue that is not consciously perceived can cause attentional facilitation followed by inhibition at the cued location. The observation of this classic biphasic effect of facilitation followed by inhibition of return (IOR) suggests that the subliminal cue captured attention in a purely exogenous way. Since IOR is not observed following endogenous shifts of spatial attention, but is observed following exogenous, stimulus-driven shifts of spatial attention, it is unlikely that top-down control settings or other non-attentional effects played a role. The current findings are interpreted in terms of a neurobiological model of visual awareness.
Mulckhuyse, M., Talsma, D., & Theeuwes, J. (2007). Grabbing attention without knowing: Automatic capture of attention by subliminal spatial cues. Visual cognition, 15(7), 779-788. https://doi.org/10.1080/13506280701307001