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Eye Movements, Visual Perception and Attention

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ClinicalTrials.gov Identifier: NCT03884985
Recruitment Status : Recruiting
First Posted : March 21, 2019
Last Update Posted : March 16, 2020
Sponsor:
Collaborator:
National Eye Institute (NEI)
Information provided by (Responsible Party):
Martina Poletti, University of Rochester

Brief Summary:
During visual fixation, small eye movements of which we are usually not aware, prevent the maintenance of a steady direction of gaze. These eye movements are finely controlled and shift retinal projection of objects within the fovea, the region of the retina where visual acuity is highest. This program of research examines the link between these eye movements and attention, and tests the hypothesis that attention, similarly to eye movements, can be controlled at the foveal level. Psychophysical experiments with human subjects, using state-of-the-art techniques, high resolution eyetracking and retinal stabilization are conducted to address these questions. Gaze-contingent calibration procedures are employed to achieve high accuracy in gaze localization. A custom developed gaze-contingent display is used to shift in real-time visual stimuli on the monitor to compensate for the observer eye movements during fixation periods and to maintain stimuli at a desired location on the retina. Experiments involve visual discrimination/detection tasks with stimuli presented at selected eccentricities within the fovea. Participants' performance and reaction times are examined under different conditions, in which various types of attention are manipulated. In addition to advancing our basic understanding of visual perception, this research leads to a better understanding of attentional control at the foveal scale and of the contribution of microscopic eye movements to the acquisition and processing of visual details.

Condition or disease Intervention/treatment Phase
Vision Other: Visual stimulation Not Applicable

Detailed Description:

The goals of this study are to the following:

  1. Examine the resolution and time-course of attention within the foveola. Attentional control has been traditionally studied outside the foveola but the PI's recent work suggests that attentional shifts also play a critical role in the normal examination of fine spatial details. Building on our previous results, we will investigate the extent by which both voluntary and involuntary attention can be controlled at this scale. Specifically, we will (a) measure the resolution of attention, i.e., the minimum distance between two locations within the foveola that can elicit selective voluntary attentional shifts. We will (b) examine whether enhancements in fine spatial vision at selected foveal locations, such as those we have previously shown for voluntary attention, also occur with involuntary attention. Finally we will study (c) the time-course of attentional enhancements and inhibition of return at this scale. Moreover, to study how peripheral and foveal attention differ, we will compare the extent of exogenous attentional effects and their time-course within and outside the foveola.
  2. Map visual acuity and crowding across the foveola. Our research has shown that vision is not uniform across the foveola: discrimination of fine spatial patterns is already suboptimal just a few arcmins away from the center of gaze. This phenomenon could be caused by a decline in visual acuity outside the preferred retinal locus and/or the consequences of crowding, the negative influence resulting from objects adjacent to the target. Because of the difficulty in precisely controlling retinal stimulation at this scale, it is unclear whether crowding occurs in the foveola, and whether its influence changes with foveal eccentricity. We will measure both visual acuity (a), and crowding (b), and will assess their relative contribution over a range of foveal eccentricities, both nasally and temporally. In addition to examine visual acuity across subjects, we will also examine how it changes at the individual level.
  3. Link attention, fine spatial vision and oculomotor control. Microsaccades normally shift the retinal projection of the fixated object across the foveola. At a larger scale, visual resolution, attention, and eye movements are tightly coupled. But little is known on whether and how this interplay unfolds within the foveola. Here we will investigate how attention and vision interact with microsaccades preparation and execution. We will examine (a) whether microsaccades preparation yields attentional benefits at specific foveal locations; (b) the precision of microsaccades; (c) their impact in attenuating negative effects of reduced acuity and foveal crowding, and; (d) their impact on performance in natural high acuity tasks.

To address these goals psychophysics experimental paradigms and high-precision eyetracking will be used.

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 50 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Basic Science
Official Title: Eye Movements, Visual Perception and Attention
Actual Study Start Date : January 1, 2015
Estimated Primary Completion Date : February 1, 2023
Estimated Study Completion Date : February 1, 2023

Arm Intervention/treatment
Experimental: Normal Vision
This study examines high-acuity vision, oculomotor behavior recorded using high-resolution eyetracking. Healthy participants are asked to perform different types of visual tasks, ranging from letter identification to judging facial expressions while their eye movements will be recorded with high-precision together with their behavioral performance in the task.
Other: Visual stimulation
In the experiments, participants will sit in front of a computer monitor located a less than a meter of distance and will analyze the content of images extracted from collections of natural and computer-generated scenes. Subjects will be asked to report verbally or by pressing keys on a keyboard on image characteristics such as the locations of the objects present in the scenes, their number and/or their identities. Some experiments will involve a search paradigm in which subjects will have to report on the location and/or fine characteristics of a target element among a field of distracting similar elements, and/or visual discrimination tasks. The duration of the interval of time in which the image is maintained on the screen may be varied between few tens of milliseconds to several seconds. In a set of experiments, the eye movements performed by the subjects during the execution of the visual tasks will be recorded as explained below.




Primary Outcome Measures :
  1. Average Performance in Visual tasks [ Time Frame: Day 0 ]
    Proportion correct responses in visual tasks


Secondary Outcome Measures :
  1. Microsaccades rate [ Time Frame: Day 0 ]
    Average number of microsaccades per second



Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Subjects will be eligible for the study if they:

    • Are at least 18 years old
    • Speak English
    • Have read, understood, and signed the informed consent form Have normal visual acuity (20/20 or better) without correction (i.e. without glasses or contact lenses) and no known visual deficits. A standard visual acuity screening will be performed by means of a Snellen chart (the standard eye chart) at the beginning and the end of the experiments.

Exclusion Criteria:

  • Subjects will be excluded if they:

    • Are under 18 years old
    • Cannot understand the experimental procedures Have reported vision loss, including the need for correction (i.e. glasses or contact lenses), or fail the visual acuity screening performed during the experiments. We expect a very minor portion of subjects to be excluded as a result of this test, as the good vision requirement will be clearly stated in our recruitment materials. There will be no data collection for subjects who will not pass the acuity test.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT03884985


Contacts
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Contact: Martina Poletti, Ph.D. 6175953785 martina.poletti@gmail.com

Locations
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United States, New York
University of Rochester Recruiting
Rochester, New York, United States, 14642
Contact: Martina Poletti, Ph.D.    617-595-3785    martina.poletti@gmail.com   
Sponsors and Collaborators
University of Rochester
National Eye Institute (NEI)
Investigators
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Principal Investigator: Martina Poletti, Ph.D. University of Rochester
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Responsible Party: Martina Poletti, Assistant Professor, University of Rochester
ClinicalTrials.gov Identifier: NCT03884985    
Other Study ID Numbers: RSRB00069578
R01EY029788-01 ( U.S. NIH Grant/Contract )
First Posted: March 21, 2019    Key Record Dates
Last Update Posted: March 16, 2020
Last Verified: March 2020
Individual Participant Data (IPD) Sharing Statement:
Plan to Share IPD: No

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Studies a U.S. FDA-regulated Drug Product: No
Studies a U.S. FDA-regulated Device Product: No