Roger Gilabert Guerrero is a professor of Applied Linguistics at the University of Barcelona and one of the key empirical collaborators on Robinson's Cognition Hypothesis. His research programme takes the theoretical taxonomy — Task Complexity, Task Condition, Task Difficulty — and runs it through a sustained set of classroom and laboratory studies on Spanish-Catalan learners of English.
The 2007 International Review of Applied Linguistics paper co-authored with Robinson is the standard reference on how to operationalise task complexity and what predictions the Cognition Hypothesis actually makes about production, interaction, and individual differences. Subsequent work has manipulated reasoning demands, number of elements, and displaced time reference across task types and modes, and extended the approach to computer-assisted collaborative writing. He sits inside the Barcelona research network that runs across Muñoz's BAF-era programme and the wider Spanish applied-linguistics community.