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Interstimulus contingency facilitates saccadic responses in a bimodal go/no-go task.
Holle Kirchner1, Hans Colonius
1Centre de Recherche Cerveau et Cognition, Faculté de Medecine, F-31062 Toulouse Cedex, France. holle.kirchner@cerco.ups-tlse.fr
Brain Research. Cognitive Brain Research
|July 26, 2005
Summary
Multisensory reactions are faster with auditory and visual cues. This study shows that predictable auditory cues, even at low probabilities, can involuntarily speed up visual-guided saccadic eye movements via top-down processing.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Human Sensory Systems
Background:
- Multisensory facilitation speeds reaction time to visual targets with nearby auditory stimuli.
- This effect is typically viewed as a mandatory bottom-up process.
- Top-down processing involves cognitive control and expectation.
Purpose of the Study:
- To investigate if multisensory facilitation of saccadic reaction time can be modulated by top-down processing.
- To determine if target location predictability influences the multisensory enhancement of saccadic eye movements.
Main Methods:
- Participants performed saccades towards visual targets.
- An accessory auditory stimulus was presented at congruent or incongruent locations with varying probabilities.
- Catch trials were included to assess response inhibition.
Main Results:
- Reaction times were facilitated in bimodal trials when target location predictability was manipulated (high 80% or low 20%).
- This facilitation occurred within a narrow time window (40 ms).
- The effect was observed even when participants could not consciously process the information.
Conclusions:
- Predictability of target location via auditory cues demonstrates top-down modulation of multisensory reaction time.
- This indicates an involuntary, rapid top-down control mechanism influencing saccadic eye movements.
- The findings challenge the notion of multisensory facilitation as purely a bottom-up process.