| Sumario: | Most studies of visuospatial short-term memory (VSSTM) rely on simplified tasks performed on vertical screens. In this study, we examine VSSTM in a more naturalistic three-dimensional context, using goal-directed throwing toward stimuli projected on the floor. Across four experiments, participants memorized spatial locations under different demands involving serial order, item–location binding, and memory load. We developed a method to dissociate spatial localization errors from transposition errors, allowing their independent contribution to performance to be quantified. When both order and location of sequentially presented targets had to be recalled, throwing accuracy followed an inverted U-shaped serial position curve, largely driven by order-related errors. Reducing spatial uncertainty during recall selectively decreased transposition errors, revealing an interaction between spatial and sequential processes. Removing serial requirements markedly reduced spatial error and improved performance for recent items. When stimuli were presented simultaneously and memory load was varied, both spatial and transposition errors increased with load, diverging from each other from three items onward. Together, these results provide behavioral evidence for multiple, separable sources of error in VSSTM and introduce a methodological framework to decompose visuomotor performance into distinct cognitive components, consistent with probabilistic models of working memory.
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