No direction specific costs in trans-saccadic memory

Working memory in action: Transsaccadic working memory deficits in the left visual field and after transcallosal remapping

Every waking second, we make three saccadic eye movements that move our retinal images. Thus, to attain a coherent image of the world we need to remember visuo-spatial information across saccades. But transsaccadic working memory (tWM) remains poorly understood. Crucially, there has been a debate whether there are any differences in tWM for the left vs. right visual field and depending on saccade direction. However, previous studies have probed tWM with minimal loads whereas spatial differences might arise with higher loads. Here we employed a task that probed higher memory load for spatial information in the left and right visual field and with horizontal as well as vertical saccades. We captured several measures of precision and accuracy of performance that, when submitted to principal component analysis, produced two components. Component 1, mainly associated with precision, yielded greater error for the left than the right visual field. Component 2 was associated with performance accuracy and unexpectedly produced a disadvantage after rightward saccades. Both components showed that performance was worse when rightward or leftward saccades afforded a shift of memory representations between visual fields compared to remapping within the same field. Our study offers several novel findings. It is the first to show that tWM involves at least two components likely reflecting working memory capacity and strategic aspects of working memory, respectively. Reduced capacity for the left, rather than the right visual field is consistent with how the left and right visual fields are known to be represented in the two hemispheres. Remapping difficulties between visual fields is consistent with the limited information transfer across the corpus callosum. Finally, the impact of rightward saccades on working memory might be due to greater interference of the accompanying shifts of attention. Our results highlight the dynamic nature of transsaccadic working memory.

Working memory in action: inspecting the systematic and unsystematic errors of spatial memory across saccades

Our ability to interact with the world depends on memory buffers that flexibly store and process information for short periods of time. Current working memory research, however, mainly uses tasks that avoid eye movements, whereas in daily life we need to remember information across saccades. Because saccades disrupt perception and attention, the brain might use special transsaccadic memory systems. Therefore, to compare working memory systems between and across saccades, the current study devised transsaccadic memory tasks that evaluated the influence of memory load on several kinds of systematic and unsystematic spatial errors, and tested whether these measures predicted performance in more established working memory paradigms. Experiment 1 used a line intersection task that had people integrate lines shown before and after saccades, and it administered a 2-back task. Experiments 2 and 3 asked people to point at one of several locations within a memory array flashed before an eye movement, and we tested change detection and 2-back performance. We found that unsystematic transsaccadic errors increased with memory load and were correlated with 2-back performance. Systematic errors produced similar results, although effects varied as a function of the geometric layout of the memory arrays. Surprisingly, transsaccadic errors did not predict change detection performance despite the latter being a widely accepted measure of working memory capacity. Our results suggest that working memory systems between and across saccades share, in part, similar neural resources. Nevertheless, our data highlight the importance of investigating working memory across saccades.