Abstract
Visual working memory (VWM) has a very limited capacity. There is an ongoing debate whether this limitation depends on the number of items that can be maintained, or it is better explained by the complexity of the maintained items, such that complex items consume more capacity relative to simple items. Recent work has argued that complexity is often confounded with familiarity, and demonstrated that familiarity also affects VWM capacity allocation, regardless of their complexity, such that unfamiliar objects consume more capacity. However, these findings where specific to experts with the complex memoranda used in the experiment, and used face-like stimuli. In the current study, we further investigated the role of familiarity in determining VWM capacity allocation, by directly manipulating the level of familiarity. In two experiments, subjects performed a change detection task in which they had to maintain simple colors, familiar music instruments and unfamiliar (exotic) music instruments. The results of the first experiment confirmed the role of familiarity in VWM: familiar objects (colors and familiar instruments) led to a better performance, compared to unfamiliar instruments, although the visual complexity of both instrument-types was similar. In Experiment two, subjects were taught for 4 sessions various details about the unfamiliar instruments and performed the change detection task before and after the learning phase. Importantly, the learning phase did not include any specific VWM-related practice. Results indicated that learning about the instruments, that is the familiarisation with them, enhanced VWM performance. Based on both experiments, we concluded that familiarity with the objects have crucial role in determining visual working memory capacity limitations, over and beyond the object complexity. Additionally, the results further highlight the interactions between long-term memory and working-memory.