Influence of removal of invisible fixation on the saccadic and manual gap effect

Hiroshi Ueda, Kohske Takahashi, Katsumi Watanabe

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Saccadic and manual reactions to a peripherally presented target are facilitated by removing a central fixation stimulus shortly before a target onset (the gap effect). The present study examined the effects of removal of a visible and invisible fixation point on the saccadic gap effect and the manual gap effect. Participants were required to fixate a central fixation point and respond to a peripherally presented target as quickly and accurately as possible by making a saccade (Experiment 1) or pressing a corresponding key (Experiment 2). The fixation point was dichoptically presented, and visibility was manipulated by using binocular rivalry and continuous flash suppression technique. In both saccade and key-press tasks, removing the visible fixation strongly quickened the responses. Furthermore, the invisible fixation, which remained on the display but suppressed, significantly delayed the saccadic response. Contrarily, the invisible fixation had no effect on the manual task. These results indicate that partially different processes mediate the saccadic gap effect and the manual gap effect. In particular, unconscious processes might modulate an oculomotor-specific component of the saccadic gap effect, presumably via subcortical mechanisms.

Original languageEnglish
Pages (from-to)329-336
Number of pages8
JournalExperimental Brain Research
Issue number1
Publication statusPublished - 2014 Jan 1



  • Binocular rivalry
  • Continuous flash suppression
  • Gap effect
  • Manual reaction time
  • Saccade

ASJC Scopus subject areas

  • Neuroscience(all)

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