Serial order in working memory: Function and nature of this coding

Verbal WM defines our ability to temporarily maintain verbal information in an activated and conscious state. This ability not only allows us to maintain the stimuli that have been presented, but importantly, also the order in which the stimuli occur. In the first part of my talk I will demonstrate that this specific aspect of WM, the order processes, are crucial in many cognitive operations such as sentence processing, new vocabulary learning, mental calculation, reading and writing abilities. Using longitudinal, cross-sectional and neuroimaging designs in typical and neurodevelopmental atypical populations, we demonstrated a specific link between serial order WM abilities and different learning abilities. In the second part of my talk I will address a fundamental question about the nature of serial order coding in WM. Many current WM models agree on the existence of positional markers for binding items and their serial position in a WM task. However, the models diverge when it comes to defining the nature of serial order coding. These models suggest the possibility of the existence of domain general ordinal positional codes, shared with other domains such as numerical or alphabetical, and based on space and/or time representations. To demonstrate this I will present two recent fMRI studies using MVPA analyses investigating the nature of ordinal representation. The aim of this talk is to give a precise idea of what order WM processing is, what it is used for and how it works.