Independent spatiotemporal effects of spatial attention and background clutter on human object location representations

Spatial attention helps us to efficiently localize objects in cluttered environments. However, the processing stage at which spatial attention modulates object location representations remains unclear. Here we investigated this question identifying processing stages in time and space in an EEG and fMRI experiment respectively. As both object location representations and attentional effects have been shown to depend on the background on which objects appear, we included object background as an experimental factor. During the experiments, human partic-ipants viewed images of objects appearing in different locations on blank or cluttered backgrounds while either performing a task on fixation or on the periphery to direct their covert spatial attention away or towards the objects. We used multivariate classification to assess object location information. Consistent across the EEG and fMRI experiment, we show that spatial attention modulated location representations during late processing stages ( > 150 ms, in middle and high ventral visual stream areas) independent of background condition. Our results clar-ify the processing stage at which attention modulates object location representations in the ventral visual stream and show that attentional modulation is a cognitive process separate from recurrent processes related to the processing of objects on cluttered backgrounds.

Automated summary

This study aimed to investigate the influence of spatial attention on object location representations, and identified processing stages in time and space through EEG and fMRI experiments. The results showed that spatial attention modulated location representations during late processing stages ( > 150 ms, in middle and high ventral visual stream areas) independent of background condition. This study clarified the processing stage at which attention modulates object location representations in the ventral visual stream and demonstrated that attentional modulation is a cognitive process separate from recurrent processes related to the processing of objects on cluttered backgrounds.