Effects Of Subliminal Non-midgamma Flicker On Spatial Attention

In the central field of vision,when the stimulus flash in a frequency which is larger than a certain value(such as,the change frequencies of brightness stimulation above about 50 Hz,the change frequency of color more than about 25 Hz),we can not perceive flicker,instead,we will perceive stable stimuli.Researchers called this phenomenon flicker fusion,and the frequency was called flicker-fusion frequency.Recently,more and more researches have showed that when the stimulus frequency was larger than the critical flicker frequency,we can not perceive flicker stimulus,but this "invisible" stimulus have affected cortical neuronal activities and cognitive processing.So far,studies on the relationship between flicker and attention are limited in luminance channel,but our visual systems not only process the luminance information,but also process color information.This study consist of two experiments,1)find a appropriate cue duration,which could trigger attentional selection in short cue-target onset asynchrony(CTOA)condition;2)using cue-target paradigm to help us examine the relationship between subliminal stimulation of color fusion and spatial attention.The results showed that: 1)it requires 500 ms to bulid up cueing effect;2)when the cue-target onset asynchrony was short(50 ms),subjects make a slower response to targets presented at the uncued locations than to those at cued locations,2)prolong cue-target onset asynchrony to 500 ms,the results was reversed.Current results suggested that,when the cue-target onset asynchrony is short,spatial attention will be caught by the subliminal cue,which was flickering at a non-Gamma central frequency band.And the shifting of spatial attention will be inhibited at long cue-target onset asynchrony condition.