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The Journal of Neuroscience, December 17, 2008, 28(51):13866-13875; doi:10.1523/JNEUROSCI.3120-08.2008

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Behavioral/Systems/Cognitive
Effects of Prior Information and Reward on Oculomotor and Perceptual Choices

Dorion B. Liston^1,2 and Leland S. Stone¹

¹NASA Ames Research Center, Moffett Field, California 94035, and ²San José State University, San José, California 95192

Correspondence should be addressed to Dorion B. Liston, NASA Ames Research Center, Mail Stop 262-2, Moffett Field, CA 94035. Email: dorion.b.liston{at}nasa.gov

Expectations about the environment influence motor behavior. In simple tasks, for example, prior knowledge about which stimulus event will likely occur or which response will likely be rewarded induces a tendency to take the favored action (i.e., a motor or response bias), especially when sensory information is sparse or ambiguous. Models of choice behavior account for this bias by weighting decision alternatives unequally, either at an early sensory-input stage or at a downstream motor-output stage. These two alternatives can be distinguished empirically; the former predicts an altered percept that correlates with motor bias, the latter predicts no perceptual effect. By varying the prior probability of target or reward location, we induced biased oculomotor responses in a brightness selection task with human subjects. We found that the induced motor bias was correlated with an amplification of both the sensory signals and internal noise underlying brightness perception, without a systematic change in perceived overall brightness. We also found that the magnitude of the sensory amplification was correlated with the amount of noise in the brightness percept, consistent with a multiplicative weighting factor located downstream from the limiting internal sensory noise. Our data demonstrate that prior knowledge (about target location or reward) shapes visual signals for perception and action in parallel but does not improve the quality (i.e., signal-to-noise ratio) of sensory processing.

Key words: saccade; attention; basal ganglia; superior colliculus; frontal eye field; lateral intraparietal area

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Received June 26, 2008; revised Oct. 20, 2008; accepted Oct. 22, 2008.

Correspondence should be addressed to Dorion B. Liston, NASA Ames Research Center, Mail Stop 262-2, Moffett Field, CA 94035. Email: dorion.b.liston{at}nasa.gov

This article has been cited by other articles:

				A. Thiele, A. Pooresmaeili, L. S. Delicato, J. L. Herrero, and P. R. Roelfsema Additive Effects of Attention and Stimulus Contrast in Primary Visual Cortex Cereb Cortex, December 1, 2009; 19(12): 2970 - 2981. [Abstract] [Full Text] [PDF]

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