Human working memory for shapes of radial frequency patterns

We investigated the human working memory for contour shapes. The memory items were radial frequency patterns (Wilkinson, Wilson, & Habak, 1998), which require global pooling of local contour orientation at the ‘intermediate’ levels of visual system. We used change-detection paradigm and d′ measure to determine the forgetting of a single pattern as a function of a retention interval, and the storage capacity for several simultaneously presented patterns. Results showed that the memory trace of a single shape is not so robust as the representations of simple features. Further, the working memory capacity for contour shapes was very low: just one item could be retained accurately.