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The main prediction was that our results should replicate the original Burkell & Pylyshyn study. For this to happen, the indices would, effectively*, have to maintain contact with the world locations of the 3 and 4 late-onset X's. This is because while the late-onset X's and the subset search items shared the same location in the world they occupied different retinal locations. Note that after the saccade (i.e., the first fixation in the search image), our experiment is like the Burkell & Pylyshyn's study in terms of type of search items and the visual angle of stimulus. We can draw the following tentative conclusions from the data so far.
If the world does change during a saccade, then what one might predict is exactly what we see: some sort of memory based task for the world locations of the 3 or 4 late-onset X's. This trans-saccadic memory representation may allow the locations of the late onset X's to be recovered after the saccade. Once recovered, the system can re-attached the indices to those locations, and only the objects at those locations are processed.
The example scanpaths in the 3 & 4 late-onset conditions show the eyes serially visiting at least some of the items in the late-onset cue locations. The eye movement pattern may reflect the spatial-temporal properties of a process of using a trans-saccadic memory of locations to re-attach visual indices. This process may be responsible for the longer response times in the 3 & 4 late-onset feature search conditions.
*There are, presumably, many ways this could be done, e.g., an extra-retinal eye position signal could be used to adjust the location of the indices with respect to new, incoming visual information after each saccade.