Combining psychophysical experiments and computational modelling, we were able to show that peripheral information before an eye movement and foveal information after an eye movement are combined close to the statistical optimum. This means that the visual system has access to the relative quality of peripheral and foveal information and weighs them accordingly. We found near-optimal integration performance for low-level visual features, such as orientation and color as well as for high-level visual features, such as numerosity, suggesting that integration across eye movements is a general principle in visual processing. High-level features are integrated even when low-level features are changed during the eye movement, indicating that integration occurs on an abstract representation rather than a pictorial representation. Integration performance is impaired by distracting attention and by increasing memory load, suggesting that integration across eye movements relies on limited resources of attention and memory. However, integration is not constrained to the eye movement target but can also occur flexibly at other, task-relevant locations in the visual field.
Interestingly, we observed one exception where peripheral and foveal information were not optimally weighted: under dim lighting conditions, participants trusted foveal information more than peripheral information, although foveal information was only inferred and not veridical due to the absence of rod photoreceptors in the fovea. This suggests that the visual system is overconfident for its own inferences.
With respect to the calibration of peripheral and foveal information, we found that there can be small mismatches in appearance between the periphery and the fovea. These appearance differences are taken into account in the perception across eye movements: stimulus changes during an eye movement are easier to detect if they are inconsistent with the typical appearance difference compared to if they are consistent with the typical appearance difference. This indicates that the visual system predicts the foveal appearance based on peripheral information and generates an expectation of the typically experienced difference between peripheral and foveal appearance. Furthermore, visual processing after an eye movement is strongly affected by visual stimulation before the eye movement and optimized for the uptake of new information.
