Attention acts to suppress goal-based conflict under high competition
  It is known that when multiple stimuli are present, top-down attention selectively enhances the neural signal in the visual cortex for task-relevant stimuli, but this has been tested only under conditions of minimal competition of visual attention. Here we show during high competition, that is, two stimuli in a shared receptive field possessing opposing modulatory goals, top-down attention suppresses both task-relevant and irrelevant neural signals within 100 ms of stimuli onset. This non-selective engagement of top-down attentional resources serves to reduce the feedforward signal representing irrelevant stimuli. 
Omar Claflin
q-bio.NC