title: Decision-making with multiple alternatives.
abstract: Simple perceptual tasks have laid the groundwork for understanding the neurobiology of decision-making. Here, we examined this foundation to explain how decision-making circuitry adjusts in the face of a more difficult task. We measured behavioral and physiological responses of monkeys on a two- and four-choice direction-discrimination decision task. For both tasks, firing rates in the lateral intraparietal area appeared to reflect the accumulation of evidence for or against each choice. Evidence accumulation began at a lower firing rate for the four-choice task, but reached a common level by the end of the decision process. The larger excursion suggests that the subjects required more evidence before making a choice. Furthermore, on both tasks, we observed a time-dependent rise in firing rates that may impose a deadline for deciding. These physiological observations constitute an effective strategy for handling increased task difficulty. The differences appear to explain subjects' accuracy and reaction times.
authors.affiliation: Howard Hughes Medical Institute, Department of Physiology and Biophysics, National Primate Research Center, University of Washington Medical School, Seattle, Washington 98195, USA. anne99@u.washington.edu
authors.forename: Anne K
authors.initials: AK
authors.lastname: Churchland
authors.forename: Roozbeh
authors.initials: R
authors.lastname: Kiani
authors.forename: Michael N
authors.initials: MN
authors.lastname: Shadlen
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal; D003657:Decision Making / Q000502:physiology*; D004192:Discrimination, Psychological / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology; D000882:Haplorhini; D009038:Motion; D009474:Neurons / Q000502:physiology*; D010296:Parietal Lobe / Q000166:cytology*; D011930:Reaction Time / Q000502:physiology; D012044:Regression Analysis; D013037:Spatial Behavior / Q000502:physiology*; D013647:Task Performance and Analysis