Visual Working Memory for sizes and orientations

Visual working memory (VWM) has become a widely discussed topic with research focusing on its capacity and units of information. Two theories have been proposed. The discretecapacity model suggests that VWM can hold a fixed number of items (~ 4) which can be manipulated and stored, regardless of the features included in the items. Contrarily, the limited-resource model supposes that VWM capacity is determined by a certain amount of resources which can be allocated flexibly to stimuli or specific features of stimuli. Past research examined mostly the representations of colors in VWM. Instead, this study focuses on rarely investigated features, namely the size and the orientation of stimuli. A delayedestimation task was employed in which participants were asked to remember the sizes and orientations of red squares. To gain a greater understanding of VWM, recall precision was examined in relation to attentional instructions, number of stimuli, and the type of feature tobe-memorized. Furthermore, an individualized stimuli set was created for each participant, to account for perceptual differences. The results show that VWM performance is influenced by the number of stimuli, as well as the attentional instructions. Additionally, recall precision was higher for sizes than for orientations, and there was an interaction effect between number of stimuli and type of feature. These findings support the limited-resource theory and the notion of multiple resource pools for different types of features. Moreover, the results suggest that VWM is interrelated with attentional process which seem to determine the allocation of resources to specific stimuli.