Limits...
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.

Show MeSH
Percentage frequency distribution histograms of saccade latency in the prosaccade overlap task.A. Example from an individual “normal” subject; B. individual ESM. In A. and B. the median saccade latency, and the percentage of express saccades is shown. C. Mean±95%CI distribution for 60 “normal” subjects. D. Mean±95%CI distribution for 16 ESMs. In C. and D. the intersubject mean (±SD) of the individual median latencies and the intersubject mean (±SD) percentage of express saccades is shown. The vertical grey region shows the range of express saccade latency (80 ms to 130 ms) and the dotted vertical line is at 100 ms. The three horizontal grey bars in C. show the three latency ranges (1 to 3) over which latency was compared between ESMs and normal subjects.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3472994&req=5

pone-0047688-g001: Percentage frequency distribution histograms of saccade latency in the prosaccade overlap task.A. Example from an individual “normal” subject; B. individual ESM. In A. and B. the median saccade latency, and the percentage of express saccades is shown. C. Mean±95%CI distribution for 60 “normal” subjects. D. Mean±95%CI distribution for 16 ESMs. In C. and D. the intersubject mean (±SD) of the individual median latencies and the intersubject mean (±SD) percentage of express saccades is shown. The vertical grey region shows the range of express saccade latency (80 ms to 130 ms) and the dotted vertical line is at 100 ms. The three horizontal grey bars in C. show the three latency ranges (1 to 3) over which latency was compared between ESMs and normal subjects.

Mentions: Prosaccade overlap data were obtained for all 77 participants. The intersubject mean median saccade latency across all 77 was 184±32 ms. However, we observed a high number of individual frequency distributions histograms (Figure 1A,B) in which there was a clear early latency peak, centred close to 100 ms (Figure 1B; all the individual frequency distributions histograms are shown in Supporting Information as Figures S1 and S2). In 17 of the 77 participants (22%), the proportion of saccades with latency in the range 80 ms to 130 ms (express saccades, ES) exceeded 30% (Figure 2). We defined these 17 participants as “express saccade makers” (ESMs) and the remaining participants as “normal”. Mean median latency and percentage of ES for the ESMs were 150±22 ms and 43±10% compared to 193±28 ms and 12±7% for the 60 normals respectively. Both latency (t = 5.67; p<0.0001) and percentage of express saccades (t = 13.37; p<0.0001) were statistically significantly different between these two groups.


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)

Percentage frequency distribution histograms of saccade latency in the prosaccade overlap task.A. Example from an individual “normal” subject; B. individual ESM. In A. and B. the median saccade latency, and the percentage of express saccades is shown. C. Mean±95%CI distribution for 60 “normal” subjects. D. Mean±95%CI distribution for 16 ESMs. In C. and D. the intersubject mean (±SD) of the individual median latencies and the intersubject mean (±SD) percentage of express saccades is shown. The vertical grey region shows the range of express saccade latency (80 ms to 130 ms) and the dotted vertical line is at 100 ms. The three horizontal grey bars in C. show the three latency ranges (1 to 3) over which latency was compared between ESMs and normal subjects.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3472994&req=5

pone-0047688-g001: Percentage frequency distribution histograms of saccade latency in the prosaccade overlap task.A. Example from an individual “normal” subject; B. individual ESM. In A. and B. the median saccade latency, and the percentage of express saccades is shown. C. Mean±95%CI distribution for 60 “normal” subjects. D. Mean±95%CI distribution for 16 ESMs. In C. and D. the intersubject mean (±SD) of the individual median latencies and the intersubject mean (±SD) percentage of express saccades is shown. The vertical grey region shows the range of express saccade latency (80 ms to 130 ms) and the dotted vertical line is at 100 ms. The three horizontal grey bars in C. show the three latency ranges (1 to 3) over which latency was compared between ESMs and normal subjects.
Mentions: Prosaccade overlap data were obtained for all 77 participants. The intersubject mean median saccade latency across all 77 was 184±32 ms. However, we observed a high number of individual frequency distributions histograms (Figure 1A,B) in which there was a clear early latency peak, centred close to 100 ms (Figure 1B; all the individual frequency distributions histograms are shown in Supporting Information as Figures S1 and S2). In 17 of the 77 participants (22%), the proportion of saccades with latency in the range 80 ms to 130 ms (express saccades, ES) exceeded 30% (Figure 2). We defined these 17 participants as “express saccade makers” (ESMs) and the remaining participants as “normal”. Mean median latency and percentage of ES for the ESMs were 150±22 ms and 43±10% compared to 193±28 ms and 12±7% for the 60 normals respectively. Both latency (t = 5.67; p<0.0001) and percentage of express saccades (t = 13.37; p<0.0001) were statistically significantly different between these two groups.

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