Working memory resources are shared across sensory modalities

Abstract A common assumption in the working memory liter-ature is that the visual and auditory modalities have separate and independent memory stores. Recent evidence on visual working memory has suggested that resources are shared between repre-sentations, and that the precision of representations sets the limit for memory performance. We tested whether memory resources are also shared across sensory modalities. Memory precision for two visual (spatial frequency and orientation) and two auditory (pitch and tone duration) features was measured separately for each feature and for all possible feature combinations. Thus, only the memory load was varied, from one to four features, while keeping the stimuli similar. In Experiment 1, two gratings and two tones—both containing two varying features—were present-ed simultaneously. In Experiment 2, two gratings and two tones—each containing only one varying feature—were present-ed sequentially. The memory precision (delayed discrimination threshold) for a single feature was close to the perceptual thresh-old. However, as the number of features to be remembered was increased, the discrimination thresholds increased more than twofold. Importantly, the decrease in memory precision did not depend on the modality of the other feature(s), or on whether the features were in the same or in separate objects. Hence, simulta-neously storing one visual and one auditory feature had an effect on memory precision equal to those of simultaneously storing two visual or two auditory features. The results show that work-ing memory is limited by the precision of the stored representa-tions, and that working memory can be described as a resource pool that is shared across modalities