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Inhibition of return, gap effect and saccadic reaction time to a visual target.
S Guimarães-Silva1, L G Gawryszewski, T S Portugal
1Departamento de Neurobiologia, Universidade Federal Fluminense, Niteroi, RJ, Brazil.
Summary
Parafoveal cues (2 degrees) can inhibit saccadic reaction time (SRT) to ipsilateral targets, suggesting a link between attention orienting and parafoveal processing.
Area of Science:
- Cognitive Neuroscience
- Visual Attention
- Oculomotor Control
Background:
- Manual reaction time (MRT) and saccadic reaction time (SRT) exhibit facilitation and inhibition of return (IOR) based on cue location and timing.
- The gap paradigm, where the fixation point disappears before target onset, shortens SRT compared to the overlap paradigm.
Purpose of the Study:
- To investigate the effect of parafoveal (2 degrees) versus peripheral (10 degrees) cues on SRT.
- To examine the influence of cue-target spatial relationships (ipsilateral vs. contralateral hemifield) and temporal paradigms (gap vs. overlap) on SRT.
Main Methods:
- Saccadic reaction time (SRT) was measured in 12 subjects responding to a visual target (S2).
- A non-informative cue (S1) was presented at either 2 or 10 degrees eccentricity, in the same or opposite hemifield as S2.
- Both gap and overlap paradigms were employed, manipulating the fixation point's presence before S2 onset.
Main Results:
- A 40-ms gap effect was observed, shortening SRT.
- Inhibition of return (IOR) resulted in a 39-ms delay when S2 appeared at the cued (S1) location.
- A significant 17-ms inhibition of SRT occurred when the parafoveal cue (2 degrees) was in the ipsilateral hemifield.
Conclusions:
- Parafoveal cues can elicit inhibition of saccadic reaction time towards ipsilateral peripheral targets.
- These findings support a functional link between covert and overt attention orienting, extending to parafoveal cueing.