The effects of enhanced attention and working memory on smooth pursuit eye movement
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It has long been suggested that increasing attentional demands can alter smooth pursuit eye movements, but the precise nature of the changes generated is not clear. Our goal was to examine smooth pursuit with a task that enhanced attention to the target and that increased demands on working memory, without distracting from the target. 15 subjects tracked a target moving around a predictable circular trajectory at a constant tangential velocity. An n-back task with two levels of additional working memory load was integrated into the pursuit target to increase cognitive demands. In the single-task conditions, subjects either performed pursuit alone or the n-back task with a stationary target. In the dual-task conditions, pursuit and the n-back task were performed together. Performance of the n-back tasks was not impaired by simultaneous smooth pursuit. The n-back tasks had negligible effects on horizontal or vertical pursuit gain, but generated increased phase lag and reduced the variability of position error during pursuit. Increasing the difficulty of the n-back task further reduced the variability of position errors. We conclude that enhanced attention does not alter the velocity gain of smooth pursuit but rather improves its consistency. As long as attention remains focused on the target, increased attentional demands further reduce pursuit variability. Increases in phase lag may serve to improve attentional processing of the target.
KeywordsOcular motor Velocity gain Phase Consistency Variability n-Back
We thank Miriam Spering for helpful discussions. JJSB was supported by a Canada Research Chair (950-228984) and the Marianne Koerner Chair in Brain Diseases. SLC was supported by the National Eye Institute of the National Institutes of Health under award number F32 EY023479. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
JLS, SLC, WJP, and JJSB conceptualized the experiment and BK assisted with computer programming. JLS conducted the testing of participants, pursuit analysis, and wrote the initial draft. JJSB performed the statistical analysis. All authors contributed to the interpretation of results, writing and approval of the final draft.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
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