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Gain control of saccadic eye movements is probabilistic

Lisi, Matteo and Solomon, Joshua A and Morgan, Michael J (2019) 'Gain control of saccadic eye movements is probabilistic.' Proceedings of the National Academy of Sciences of USA, 116 (32). pp. 16137-16142. ISSN 0027-8424

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Saccades are rapid eye movements that orient the visual axis toward objects of interest to allow their processing by the central, high-acuity retina. Our ability to collect visual information efficiently relies on saccadic accuracy, which is limited by a combination of uncertainty in the location of the target and motor noise. It has been observed that saccades have a systematic tendency to fall short of their intended targets, and it has been suggested that this bias originates from a cost function that overly penalizes hypermetric errors. Here, we tested this hypothesis by systematically manipulating the positional uncertainty of saccadic targets. We found that increasing uncertainty produced not only a larger spread of the saccadic endpoints but also more hypometric errors and a systematic bias toward the average of target locations in a given block, revealing that prior knowledge was integrated into saccadic planning. Moreover, by examining how variability and bias covaried across conditions, we estimated the asymmetry of the cost function and found that it was related to individual differences in the additional time needed to program secondary saccades for correcting hypermetric errors, relative to hypometric ones. Taken together, these findings reveal that the saccadic system uses a probabilistic-Bayesian control strategy to compensate for uncertainty in a statistically principled way and to minimize the expected cost of saccadic errors.

Item Type: Article
Uncontrolled Keywords: motor control; eye movements; cost function; saccades
Divisions: Faculty of Science and Health
Faculty of Science and Health > Psychology, Department of
SWORD Depositor: Elements
Depositing User: Elements
Date Deposited: 21 Sep 2020 18:46
Last Modified: 06 Jan 2022 14:09

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