Psychophysical Research On The Mechanism Of Visual Spatial Attention And Feature Attention Based On Pre-cueing Paradigm

To efficiently use its limited processing capacity,our brain selectively processes the behavior relevant visual signals with priority,while other informations are ignored.The mechanism of this selective attention is always an essential research topic in cognitive neuroscience.Even though it has been extensively investigatgesd by numerious researches,many key scientific problems still remain.We did psychophysical research to investigate some problems about the mechanism of selective attention on the basis of pre-cueing paradigm.This thesis is consisted of the following parts.Attentional field size is an important characteristic of spatial attention,which can influence perception and related behavior.Determining factors that impact attention field size and finding effective methods to manipulate the spatial extent of attention focus in practical experiment are necessary.We innovately combined two methods that were previously used to adjust attention field size within one protocal: varying the uncertainty about the target location and adjusting the size of the cue orienting the attention focus.And we systematically assessed and directly compared the effectiveness of these methods.Our results indicate that adjusting spatial uncertainty is more effective than varying cue size when manipulating attention field size.When it comes to modulation which is relevevant to attention,the temporal dynamics of this modulation is nonnegligible.To futher investigate the mechanism of spatial uncertainty modulation,we explored the time couse of this modulation in detail.Different numbers of central cues or peripheral cues indicating the potential locations of the target were used to indicate discrepant levels of spatial uncertainty.The stimulus onset asynchrony between the cue and the target was also systematically varied to assess the changes of the modulation over time.We found that under central cueing,the effect of spatial uncertainty modulation took 200 ms to establish after the presence of the cue.But under peripheral cueing,the effect of spatial uncertainty modulation was observed 50 ms after cueing.Our results provide a new empirical evidence for the idea that discrepant processing procedures are involved under different cueing conditions.We also found that once the modulation effect was established,it could last until the completion of the task.Except for spatial attention,feature-based attention(FBA)is also a very important type of attention.However,we know little about the underlying mechanism of FBA.Previous studies have indicated that FBA effects can be explained only by passive priming due to the preceding processing of that feature.However,it's controversial about whether FBA can occur purely on the basis of top-down attentional set.In this study,we used an orientation discrimination task with pre-cueing of the target orientation.And we eliminated the influence of priming and visuospatial attention through careful design.We found whether cue validity influenced discrimination speed was determined by whether the feature cue was informative regarding the target orientation.Our findings suggest that FBA effects can occur purely based on top-down attentional processing.Our findings provide new insights in the mechanism of FBA.Our study does not only deepen and extend the understandings on the mechanism of selective attention,but also builds theoretical and empirical foundation for future study in relevant fields.