Abstract
Express saccades are low latency (80–130 ms), visually guided saccades. While their occurrence is encouraged by the use of gap tasks (the fixation target is extinguished 200 ms prior to the saccade target appearing) and suppressed by the use of overlap tasks (the fixation target remains present when the saccade target appears), there are some healthy, adult participants, “express saccade makers” (ESMs), who persist in generating high proportions (> 30%) of express saccades in overlap conditions. These participants are encountered much more frequently in Chinese participant groups than amongst the Caucasian participants tested to date. What is not known is whether this high number of ESMs is only a feature of Chinese participant groups. More broadly, there are few comparative studies of saccade behaviour across large participant groups drawn from different populations. We, therefore, tested an independent group of 70 healthy adult Egyptian participants, using the same equipment and procedures as employed in the previous studies. Each participant was exposed to two blocks of 200 gap, and two blocks of 200 overlap trials, with block order counterbalanced. Results from the Schwartz Value Survey were used to confirm that this group of participants was culturally distinct from the Chinese and Caucasian (white British) groups tested previously. Fourteen percent (10/70) of this new group were ESMs, and the pattern of latency distribution in these ESMs was identical to that identified in the other participant groups, with a prominent peak in the express latency range in overlap conditions. Overall, we identified three modes in the distribution of saccade latency in overlap conditions, the timing of which (express peak at 110 ms, subsequent peaks at 160 and 210 ms) were strikingly consistent with our previous observations. That these behavioural patterns of saccade latency are observed consistently in large participant groups, drawn from geographically, ethnically, and culturally distinct populations, suggests that they relate to the underlying architecture of the saccade system.
Highlights
Electronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.“Express” saccades (ES), are reflexive, visually guided saccades that have a latency which is consistent with the minimum afferent and efferent conduction times between the retina and the external oculomotor plant (Fischer et al 1993; Dorris et al 1997)
We examined the pattern of distribution of saccade latency in these participants and established the proportion of express saccade makers” (ESMs)
Using a 3 × 10 repeated-measures Analysis of variance (ANOVA), we found that both value (F9,1341 = 40.54, p < 0.001, ηp2 = 0.21) and group (F2,149 = 19.40, p < 0.001, ηp2 = 0.21) had a statistically significant effect on value scores and there was a significant interaction between them (F18,1341 = 24.32, p < 0.001, ηp2 = 0.25)
Summary
Electronic supplementary material The online version of this article (doi:10.1007/s00221-017-5094-1) contains supplementary material, which is available to authorized users.“Express” saccades (ES), are reflexive, visually guided saccades that have a latency which is consistent with the minimum afferent and efferent conduction times between the retina and the external oculomotor plant (Fischer et al 1993; Dorris et al 1997). Single unit recording in non-human primates has shown that ES production is critically dependant on the superior colliculus where visual responses are transformed into saccade motor commands (Schiller et al 1987). Exp Brain Res (2017) 235:3733–3742 saccade latency distributions are plotted, ES may form a distinct, early mode in the distribution. This pattern, while observed in non-human primates (Fischer and Boch 1983; Schiller et al 1987), was not always observed in human studies, leading to considerable controversy (Fischer et al 1993; Kalesnykas and Hallett 1987; Kingstone and Klein 1993; Reuter-Lorenz et al 1991; Wenban-Smith and Findlay 1991). Stimulus features and paradigm design influence saccade latency range, the shape of its distribution, and the proportion of ES (Carpenter 2001; Jüttner and Wolf 1992; Marino et al 2012, 2015)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
