title: Chunking as the result of an efficiency computation trade-off.
abstract: How to move efficiently is an optimal control problem, whose computational complexity grows exponentially with the horizon of the planned trajectory. Breaking a compound movement into a series of chunks, each planned over a shorter horizon can thus reduce the overall computational complexity and associated costs while limiting the achievable efficiency. This trade-off suggests a cost-effective learning strategy: to learn new movements we should start with many short chunks (to limit the cost of computation). As practice reduces the impediments to more complex computation, the chunking structure should evolve to allow progressively more efficient movements (to maximize efficiency). Here we show that monkeys learning a reaching sequence over an extended period of time adopt this strategy by performing movements that can be described as locally optimal trajectories. Chunking can thus be understood as a cost-effective strategy for producing and learning efficient movements.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois 60611, USA.|Rehabilitation Institute of Chicago, Chicago, Illinois 60611, USA.
authors.forename: Pavan
authors.initials: P
authors.lastname: Ramkumar
authors.affiliation: Rehabilitation Institute of Chicago, Chicago, Illinois 60611, USA.|School of Information Studies, Syracuse University, Syracuse, New York 13244, USA.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Acuna
authors.affiliation: Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois 60611, USA.|Department of Mechanical and Industrial Engineering, University of Illinois, Chicago, Illinois 60607, USA.
authors.forename: Max
authors.initials: M
authors.lastname: Berniker
authors.affiliation: Department of Psychological and Brain Sciences, University of California, Santa Barbara, California 93106, USA.
authors.forename: Scott T
authors.initials: ST
authors.lastname: Grafton
authors.affiliation: Department of Neurobiology and Systems Neurosciences Institute, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: Robert S
authors.initials: RS
authors.lastname: Turner
authors.affiliation: Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, Illinois 60611, USA.|Rehabilitation Institute of Chicago, Chicago, Illinois 60611, USA.
authors.forename: Konrad P
authors.initials: KP
authors.lastname: Kording
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D004526:Efficiency; D005260:Female; D007858:Learning; D008253:Macaca mulatta; D008954:Models, Biological; D009068:Movement