title: Task switching in a hierarchical task structure: evidence for the fragility of the task repetition benefit.
abstract: This study examined how task switching is affected by hierarchical task organization. Traditional task-switching studies, which use a constant temporal and spatial distance between each task element (defined as a stimulus requiring a response), promote a flat task structure. Using this approach, Experiment 1 revealed a large switch cost of 238 ms. In Experiments 2-5, adjacent task elements were grouped temporally and/or spatially (forming an ensemble) to create a hierarchical task organization. Results indicate that the effect of switching at the ensemble level dominated the effect of switching at the element level. Experiments 6 and 7, using an ensemble of 3 task elements, revealed that the element-level switch cost was virtually absent between ensembles but was large within an ensemble. The authors conclude that the element-level task repetition benefit is fragile and can be eliminated in a hierarchical task organization.
authors.affiliation: National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA 94035, USA. mclien@mail.arc.nasa.gov
authors.forename: Mei-Ching
authors.initials: MC
authors.lastname: Lien
authors.forename: Eric
authors.initials: E
authors.lastname: Ruthruff
mesh_terms: D006801:Humans; D007600:Judgment; D011930:Reaction Time; D013998:Time Perception