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Testing a simplified method for measuring velocity integration in saccades using a manipulation of target contrast.

Etchells PJ, Benton CP, Ludwig CJ, Gilchrist ID - Front Psychol (2011)

Bottom Line: Observers generated saccades to one of two moving targets which were presented at high (80%) or low (7.5%) contrast.The extent to which the saccade endpoint can be accounted for as a weighted combination of the pre- or post-step velocities allows for identification of the temporal velocity integration window.Our results show that the temporal integration window takes longer to peak in the low when compared to high contrast condition.

View Article: PubMed Central - PubMed

Affiliation: School of Experimental Psychology, University of Bristol Bristol, UK.

ABSTRACT
A growing number of studies in vision research employ analyses of how perturbations in visual stimuli influence behavior on single trials. Recently, we have developed a method along such lines to assess the time course over which object velocity information is extracted on a trial-by-trial basis in order to produce an accurate intercepting saccade to a moving target. Here, we present a simplified version of this methodology, and use it to investigate how changes in stimulus contrast affect the temporal velocity integration window used when generating saccades to moving targets. Observers generated saccades to one of two moving targets which were presented at high (80%) or low (7.5%) contrast. In 50% of trials, target velocity stepped up or down after a variable interval after the saccadic go signal. The extent to which the saccade endpoint can be accounted for as a weighted combination of the pre- or post-step velocities allows for identification of the temporal velocity integration window. Our results show that the temporal integration window takes longer to peak in the low when compared to high contrast condition. By enabling the assessment of how information such as changes in velocity can be used in the programming of a saccadic eye movement on single trials, this study describes and tests a novel methodology with which to look at the internal processing mechanisms that transform sensory visual inputs into oculomotor outputs.

No MeSH data available.


Related in: MedlinePlus

Velocity integration filters for all six observers in Experiment 1. Solid dark blue line denotes the plot based on the high contrast data; dashed light blue line denotes the plot for the low-contrast data. Shaded areas indicate 95% confidence limits based on 10,000 bootstrap replications (dark blue and light green for high and low-contrast conditions, respectively).
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Figure 5: Velocity integration filters for all six observers in Experiment 1. Solid dark blue line denotes the plot based on the high contrast data; dashed light blue line denotes the plot for the low-contrast data. Shaded areas indicate 95% confidence limits based on 10,000 bootstrap replications (dark blue and light green for high and low-contrast conditions, respectively).

Mentions: Figure 5 shows, for each observer, the derivatives of the weight versus D functions for both contrast conditions. The solid black line shows the filter plot for the high contrast data, and the dashed line shows the filter plot for the low-contrast data. The corresponding shaded regions denote the 95% confidence intervals. These were calculated by producing 1000 bootstrap replications of the fit parameters, using the percentile method (Efron and Tibshirani, 1993).


Testing a simplified method for measuring velocity integration in saccades using a manipulation of target contrast.

Etchells PJ, Benton CP, Ludwig CJ, Gilchrist ID - Front Psychol (2011)

Velocity integration filters for all six observers in Experiment 1. Solid dark blue line denotes the plot based on the high contrast data; dashed light blue line denotes the plot for the low-contrast data. Shaded areas indicate 95% confidence limits based on 10,000 bootstrap replications (dark blue and light green for high and low-contrast conditions, respectively).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3108583&req=5

Figure 5: Velocity integration filters for all six observers in Experiment 1. Solid dark blue line denotes the plot based on the high contrast data; dashed light blue line denotes the plot for the low-contrast data. Shaded areas indicate 95% confidence limits based on 10,000 bootstrap replications (dark blue and light green for high and low-contrast conditions, respectively).
Mentions: Figure 5 shows, for each observer, the derivatives of the weight versus D functions for both contrast conditions. The solid black line shows the filter plot for the high contrast data, and the dashed line shows the filter plot for the low-contrast data. The corresponding shaded regions denote the 95% confidence intervals. These were calculated by producing 1000 bootstrap replications of the fit parameters, using the percentile method (Efron and Tibshirani, 1993).

Bottom Line: Observers generated saccades to one of two moving targets which were presented at high (80%) or low (7.5%) contrast.The extent to which the saccade endpoint can be accounted for as a weighted combination of the pre- or post-step velocities allows for identification of the temporal velocity integration window.Our results show that the temporal integration window takes longer to peak in the low when compared to high contrast condition.

View Article: PubMed Central - PubMed

Affiliation: School of Experimental Psychology, University of Bristol Bristol, UK.

ABSTRACT
A growing number of studies in vision research employ analyses of how perturbations in visual stimuli influence behavior on single trials. Recently, we have developed a method along such lines to assess the time course over which object velocity information is extracted on a trial-by-trial basis in order to produce an accurate intercepting saccade to a moving target. Here, we present a simplified version of this methodology, and use it to investigate how changes in stimulus contrast affect the temporal velocity integration window used when generating saccades to moving targets. Observers generated saccades to one of two moving targets which were presented at high (80%) or low (7.5%) contrast. In 50% of trials, target velocity stepped up or down after a variable interval after the saccadic go signal. The extent to which the saccade endpoint can be accounted for as a weighted combination of the pre- or post-step velocities allows for identification of the temporal velocity integration window. Our results show that the temporal integration window takes longer to peak in the low when compared to high contrast condition. By enabling the assessment of how information such as changes in velocity can be used in the programming of a saccadic eye movement on single trials, this study describes and tests a novel methodology with which to look at the internal processing mechanisms that transform sensory visual inputs into oculomotor outputs.

No MeSH data available.


Related in: MedlinePlus