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Stephen M. Emrich, Susanne Ferber; Increasing visual short-term memory load impairs object processing in the left visual field. Journal of Vision 2007;7(9):660. doi: 10.1167/7.9.660.
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© ARVO (1962-2015); The Authors (2016-present)
After lesions to temporo-parietal regions, patients with visuospatial neglect demonstrate a profound deficit in awareness for contents in the contralateral visual field. Likewise, individuals suffering form extinction demonstrate an impaired awareness for stimuli in one visual field under the presence of bilaterally presented stimuli. While neglect and extinction have traditionally been associated with impaired attentional processing, current models of neglect suggest that it is also associated with a profound deficit in visuo-spatial memory. Interestingly, recent experiments have demonstrated that increases in visual short-term memory (VSTM) load produce decreases in neural activity in the right temporo-parietal junction (TPJ), the same region associated with neglect. These experiments also demonstrate that this decrease may be associated with inattentional blindness. Here, we tested whether increases in VSTM load could produce deficits in awareness for objects presented on the left visual field. Under a low or high VSTM load, participants had to indicate the number and identities of objects that were briefly presented to the left and/or right visual fields during the memory delay. Results demonstrate that under the high memory-load condition individuals were equally accurate in reporting the number of objects regardless of visual field, or whether objects were presented unilaterally or bilaterally. However, accuracy in reporting the objects' identities was impaired under bilateral presentation relative to unilateral conditions. Interestingly, we also demonstrate that this impairment in object processing was significantly worse in the left visual field compared to the right under high memory load. The results demonstrate that high VSTM load can produce an extinction-like deficit for the recognition of objects in the left visual field.
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