The oculomotor gap effect without a foveal fixation point

Robert Fendrich, Shaban Demirel, Shai Danziger

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


Turning off a fixation point prior to or coincident with the appearance of a visual target reduces the latency of saccades to that target. We investigated this 'gap effect' when subjects fixated a central point or the center of a square formed by four points that were 4, 2 or 1°eccentric from the square's center. The fixation anchor vanished 200 ms prior to the appearance of a saccadic target in a Gap condition, coincident with the target's appearance in a 0-Gap condition, or remained on in an Overlap condition. Saccadic reaction time was reduced in the Gap relative to O-Gap condition irrespective of the type of fixation anchor However, saccadic reaction time was not reduced in the O-Gap relative to Overlap condition when the points forming the Square had eccentricities of 2 or 4°. Results are interpreted in terms of a partial mediation of the gap effect by fixation cells in the rostral pole of the superior colliculus.

Original languageEnglish
Pages (from-to)833-841
Number of pages9
JournalVision Research
Issue number4
StatePublished - 2 Feb 1999
Externally publishedYes


  • Fixation cells
  • Gap effect
  • Saccadic reaction times
  • Superior colliculus

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems


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