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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

D (time between velocity change and saccade onset) versus the x-component error in saccade landing positions for a single observer (observer 1). Data are separated out by contrast condition. Green triangles denote speed step up trials; blue circles denote speed step down trials. Predicted behavior based solely on the post-step speed corresponds to zero-error (i.e., the x-axis). Predicted behavior based solely on the pre-step speed is shown by the red dashed lines.
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Figure 3: D (time between velocity change and saccade onset) versus the x-component error in saccade landing positions for a single observer (observer 1). Data are separated out by contrast condition. Green triangles denote speed step up trials; blue circles denote speed step down trials. Predicted behavior based solely on the post-step speed corresponds to zero-error (i.e., the x-axis). Predicted behavior based solely on the pre-step speed is shown by the red dashed lines.

Mentions: Figure 3 shows, for a single observer, this landing position error as a function of D for both high and low-contrast conditions.


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)

D (time between velocity change and saccade onset) versus the x-component error in saccade landing positions for a single observer (observer 1). Data are separated out by contrast condition. Green triangles denote speed step up trials; blue circles denote speed step down trials. Predicted behavior based solely on the post-step speed corresponds to zero-error (i.e., the x-axis). Predicted behavior based solely on the pre-step speed is shown by the red dashed lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: D (time between velocity change and saccade onset) versus the x-component error in saccade landing positions for a single observer (observer 1). Data are separated out by contrast condition. Green triangles denote speed step up trials; blue circles denote speed step down trials. Predicted behavior based solely on the post-step speed corresponds to zero-error (i.e., the x-axis). Predicted behavior based solely on the pre-step speed is shown by the red dashed lines.
Mentions: Figure 3 shows, for a single observer, this landing position error as a function of D for both high and low-contrast conditions.

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