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Performance deficits in a voluntary saccade task in Chinese "express saccade makers".

Knox PC, Amatya N, Jiang X, Gong Q, Gong Q - PLoS ONE (2012)

Bottom Line: Differences in behaviour and cognition have been observed in different human populations.However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks).These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population.

View Article: PubMed Central - PubMed

Affiliation: Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom. pcknox@liv.ac.uk

ABSTRACT
Differences in behaviour and cognition have been observed in different human populations. It has been reported that in various types of complex visual task, eye movement patterns differ systematically between Chinese and non-Chinese participants, an observation that has been related to differences in culture between groups. However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks). These participants are defined as "express saccade makers" (ESMs). We then show using the antisaccade paradigm, which requires the inhibition of reflexive responses and the programming and execution of voluntary saccades, that the performance of ESMs is compromised; they have higher antisaccade directional error rates, and the latency distributions of their error saccades again exhibit a higher proportion of low latency express saccade errors consistent with a reduced ability to inhibit reflexive responses. These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population. They suggest a potential unexpected confound relevant to those studies of Chinese versus other groups which have investigated group differences using oculomotor measures, and explained them in terms of culture. The confirmation of higher numbers of ESMs among Chinese participants provides new opportunities for examining oculomotor control.

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Data from antisaccade tasks.Comparison of mean±95%CI between 60 normal (non-ESM) subjects and 16 ESMs. A. Antisaccade directional error rate. B. Mean error pro-saccade latency. C. Mean correct antisaccade latency. Note different y-axis scales in B and C.
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pone-0047688-g003: Data from antisaccade tasks.Comparison of mean±95%CI between 60 normal (non-ESM) subjects and 16 ESMs. A. Antisaccade directional error rate. B. Mean error pro-saccade latency. C. Mean correct antisaccade latency. Note different y-axis scales in B and C.

Mentions: Of the 17 ESM participants, antisaccade data were obtained for 16. Subsequent analysis is based on this group of 16 ESMs (median age 24 y, 7 males) compared to a group of 60 normal participants (median age 23.5 y, 30 males). ESM antisaccade directional error rate (41±24%; Figure 3A) was statistically significantly higher (t = 2.5, p = 0.01) compared to the normal participants (28±16%). Error pro-saccade latency (ie saccades directed at the target in the antisaccade task, ErrPS) and correct antisaccade latency (CorAS) were analysed. For all bar one of the normal participants, and all of the ESMs, median ErrPS latency was less than that of CorAS latency. However, the intersubject mean difference between the medians (CorAS-ErrPS) was 97±54 ms and 127±45 ms for the normal and ESM groups respectively; this difference was statistically significant (t = 2.01, p<0.05). The reason for this greater difference in the EMSs was that while CorAS latency was identical between the groups (Figure 3C; Norm: 290±61 ms vs ESM:290±37 ms), the ErrPS latency was lower in the ESMs (Figure 3B; Norm:193±31 ms vs ESM: 164±35 ms). When investigated with a repeated measures ANOVA with saccade type (ErrPS vs CorAS) as a within subjects factor, and group (Norm vs ESM) as a between subjects factor, saccade type was significant (F1,74 = 233.9, p<0.001) while group was not (F1,74 = 1.9, p = 0.187). The interaction between type and group was statistically significant (F1,74 = 4.1, p = 0.045).


Performance deficits in a voluntary saccade task in Chinese "express saccade makers".

Knox PC, Amatya N, Jiang X, Gong Q, Gong Q - PLoS ONE (2012)

Data from antisaccade tasks.Comparison of mean±95%CI between 60 normal (non-ESM) subjects and 16 ESMs. A. Antisaccade directional error rate. B. Mean error pro-saccade latency. C. Mean correct antisaccade latency. Note different y-axis scales in B and C.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3472994&req=5

pone-0047688-g003: Data from antisaccade tasks.Comparison of mean±95%CI between 60 normal (non-ESM) subjects and 16 ESMs. A. Antisaccade directional error rate. B. Mean error pro-saccade latency. C. Mean correct antisaccade latency. Note different y-axis scales in B and C.
Mentions: Of the 17 ESM participants, antisaccade data were obtained for 16. Subsequent analysis is based on this group of 16 ESMs (median age 24 y, 7 males) compared to a group of 60 normal participants (median age 23.5 y, 30 males). ESM antisaccade directional error rate (41±24%; Figure 3A) was statistically significantly higher (t = 2.5, p = 0.01) compared to the normal participants (28±16%). Error pro-saccade latency (ie saccades directed at the target in the antisaccade task, ErrPS) and correct antisaccade latency (CorAS) were analysed. For all bar one of the normal participants, and all of the ESMs, median ErrPS latency was less than that of CorAS latency. However, the intersubject mean difference between the medians (CorAS-ErrPS) was 97±54 ms and 127±45 ms for the normal and ESM groups respectively; this difference was statistically significant (t = 2.01, p<0.05). The reason for this greater difference in the EMSs was that while CorAS latency was identical between the groups (Figure 3C; Norm: 290±61 ms vs ESM:290±37 ms), the ErrPS latency was lower in the ESMs (Figure 3B; Norm:193±31 ms vs ESM: 164±35 ms). When investigated with a repeated measures ANOVA with saccade type (ErrPS vs CorAS) as a within subjects factor, and group (Norm vs ESM) as a between subjects factor, saccade type was significant (F1,74 = 233.9, p<0.001) while group was not (F1,74 = 1.9, p = 0.187). The interaction between type and group was statistically significant (F1,74 = 4.1, p = 0.045).

Bottom Line: Differences in behaviour and cognition have been observed in different human populations.However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks).These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population.

View Article: PubMed Central - PubMed

Affiliation: Eye and Vision Science, Institute of Ageing and Chronic Disease, University of Liverpool, Liverpool, United Kingdom. pcknox@liv.ac.uk

ABSTRACT
Differences in behaviour and cognition have been observed in different human populations. It has been reported that in various types of complex visual task, eye movement patterns differ systematically between Chinese and non-Chinese participants, an observation that has been related to differences in culture between groups. However, we confirm here that, in healthy, naïve adult Chinese participants, a far higher proportion (22%) than expected (1-5%) exhibit a pattern of reflexive eye movement behaviour (high numbers of low latency express saccades) in circumstances designed to inhibit such responses (prosaccade overlap tasks). These participants are defined as "express saccade makers" (ESMs). We then show using the antisaccade paradigm, which requires the inhibition of reflexive responses and the programming and execution of voluntary saccades, that the performance of ESMs is compromised; they have higher antisaccade directional error rates, and the latency distributions of their error saccades again exhibit a higher proportion of low latency express saccade errors consistent with a reduced ability to inhibit reflexive responses. These results are difficult to reconcile with a cultural explanation as they relate to important and specific performance differences within a particular population. They suggest a potential unexpected confound relevant to those studies of Chinese versus other groups which have investigated group differences using oculomotor measures, and explained them in terms of culture. The confirmation of higher numbers of ESMs among Chinese participants provides new opportunities for examining oculomotor control.

Show MeSH