Attention modulates the binding of information across the 2-D visual array

We examined the modulating role that attention exerts on the integration of information in space and time to produce the common perceptual experience of a line and a square. The design comprised a 2-D search space, made of four distinct spatial locations (one per element of a line in experiment 1 or per corner of a square in experiment 2) by eight temporal lags (linear incre- ments of 26.6 ms with an eighth lag of 400 ms). In each trial (lasting 667 ms), a fixation cross appeared first for 1 s followed by a line constructed from three synchronous and one asynchro- nous element whose position and temporal asynchrony were randomly sampled from the 2-D space. We manipulated attention with a non-predictive cue, presented for 67 ms above one element position (the left and right elements of the line in experiment 1; one of the four corners in experiment 2), but only 150 ms prior to asynchrony onset, to rule out eye movements. In a 2AFC task, observers responded whether the stimulus was continous or discontinuous. We found that the perceptions of the continuous line and square were warped in space^time around the foci of attention.