Abstract
Several studies have investigated object-based capacity limitations of visual short-term memory (VSTM) (e.g. Luck & Vogel, 1997; Alvarez & Cavanagh, 2001). Recently research interest has turned from object-based processing towards the resolution of objects retained in short-term memory (e.g. Wilken & Ma, 2004). Although this research is highly relevant, there may be an inherent difference whether a stimulus can be easily classified in a discrete category, or if it belongs on a spectrum of a continuous category. Previous studies have shown that object based capacity of VSTM is not only limited by object complexity as argued by Alvarez & Cavanagh (2001), but also relates to familiarity and expertise (Sørensen & Kyllingsbæk, 2012; Dall, Watanabe, & Sørensen, 2016). Here we investigated the influence of two vectors of complexity, namely the number of features that the constitute an object versus the degree of familiarity with said object. We presented Chinese observers with a whole report design (see Sperling, 1960), consisting of four stimulus conditions. Chinese characters varied along two aspects: the word frequency and the number of strokes used in the character. Data were analysed using the Theory of Visual Attention (Bundesen, 1990) enabling us to isolate specific components of attention; VSTM capacity (K), as well as parameters like processing speed (C), and the threshold for visual perception (t0) (e.g. Ásgeirsson, Nordfang & Sørensen, 2015). The threshold of visual perception was not affected by the manipulation of stroke count, nor by character frequency. In turn we found a consistent pattern in both processing speed and capacity of VSTM revealing that observer performance was driven mainly by familiarity, and not stroke count, demonstrating that object complexity is dependent on the robustness of an observer's mental categories, rather than on the number of features in the object per se.
Meeting abstract presented at VSS 2017