Bottom-up effects modulate saccadic latencies in well-known eye movement paradigm
- 91 Downloads
A well-known eye movement paradigm combines saccades (fast eye movements) with a perceptual discrimination task. At a variable time after the onset of a central arrow cue indicating the target direction [the stimulus onset asynchrony (SOA)], discrimination symbols appear briefly at saccade target and non-target locations. A previous study revealed an unexpected effect of SOA on saccadic latencies: latencies were longer in trials with longer SOAs. It was suggested that this effect reflects a top-down process as observers may wait for the discrimination symbol to appear before executing saccades. However, symbol onsets may also modulate saccade latencies from the bottom-up. To clarify the origin of the SOA effect on latencies in this paradigm, we used a simplified version of the original task plus two new symbol onset conditions for comparison. The results indicate that the modulation of saccadic latencies was not due to a top-down strategy, but to a combination of two opposing bottom-up effects: the symbol onsets at the target location shortened saccade latencies, while symbol onsets at non-target locations lengthened saccade latencies.
KeywordsTarget Location Stimulus Onset Asynchrony Superior Colliculus Catch Trial Saccade Latency
This research was supported by a FRST Doctoral Scholarship (SvS) and a New Zealand Lottery Grant.
- Everling, S., Pare, M., Dorris, M. C., & Munoz, D. P. (1998). Comparison of the discharge characteristics of brain stem omnipause neurons and superior colliculus fixation neurons in monkey: Implications for control of fixation and saccade behavior. Journal of Neurophysiology, 79(2), 511–528.PubMedGoogle Scholar