Abstract
Much of what we know about visual working memory has been uncovered using simple stimuli such as colored squares, but recent studies have suggested that alternative conclusions can be drawn using different stimuli, such as real world objects. For instance, visual working memory capacity has been estimated to be higher for images of real-world objects than for colored squares (Brady et al, 2016; Asp et al, pp2019; but see Quirk & Vogel, VSS 2017). A possible explanation as to why these differences exist is because objects are redundantly coded broadly across several brain regions, where simple stimuli like colored squares are encoded in a more limited set of regions. Because of this redundant coding, it could be that incidental features of complex objects, like their spatial position, are represented with greater precision, since multiple spatial representations across brain regions may average out (Foster et al. 2017). We tested this possibility with a delayed spatial recall task in which participants remembered arrays of either real world objects or colored squares. Participants (N=11) maintained the precise spatial position of 1, 2, or 6 visual stimuli over a brief 1.5s delay period. Stimuli were either images of categorically-distinct real-world objects (courtesy of Brady et al. 2008), or easily-discriminable colored squares. Contrary to our predictions, participants recalled spatial positions with equivalent precision in the two stimulus conditions. Moreover, in separate trials where participants discriminated which of two stimuli appeared at a probed location, performance was again identical between stimulus conditions. Altogether, these results do not support the notion that incidental features of real-world objects, such as their spatial position, can be remembered with greater precision than those for simplistic stimuli typically used in laboratory tests.