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NCT Number: NCT06587113

An Investigation of Attentional and Inhibitory Processes During Active Visual Search in Humans

The goal of this study is to investigate the finding that there are large individual differences in how participants move their eyes during active visual search. For example, some individuals tend to fixate, that is point their eyes steadily at a single location, for longer than other individuals before moving to another location. This experiment will use behavioral tasks to measure an individual's attentional and inhibitory functioning, and then see how each of these contributes to between-participant variability in eye movement behavior during visual search.

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Key information

Conditions

Eye Movements Attention Behavior Executive Function Inhibition, Psychological

Age range

18 year–65 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

About this study

To accomplish the goal of understanding the source of individual variability in eye movement patterns, each participant will complete three separate tasks. The first task will require participants to find a target and eye movements will be measured to assess individual differences in fixation duration and other types of eye movement behavior. A second task will evaluate attentional functioning over the visual field by requiring participants to detect briefly-presented targets using their peripheral vision. Finally, a third task will assess inhibitory functioning by having participants attempt to stop eye movements after they have been programmed.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 18-65 years old

Exclusion criteria

  • Self-reported history of neurological illness
  • Uncorrected vision problems

Treatment and study plan

Contour Search Task

Other

In this task, participants sit in front of a computer screen with their head in a chinrest to control for distance from the monitor and eye-tracking equipment. For the visual search task, participants will search for a visual target among distractors and make a response regarding its orientation. The target is defined by a contour formed through oriented Gabor patches.

Stop Signal Task

Behavioral

In this task, participants sit in front of a computer screen with their head in a chinrest to control for distance from the monitor and eye-tracking equipment. For the stop-signal task, participants will make an eye movement to a target that appears on the screen, except on trials where a visual signal appears indicating they should cancel this behavior.

Other names: SST, SSRT

Useful field of View

Behavioral

In this task, participants sit in front of a computer screen with their head in a chinrest to control for distance from the monitor and eye-tracking equipment. In the useful field of view task, participants will report the location of a briefly-presented and masked target, while also responding to the identify of a central target in some blocks.

Attentional capture search task

Behavioral

In this task, participants sit in front of a computer screen with their head in a chinrest to control for distance from the monitor and eye-tracking equipment. For this visual search task, participants will search for a visual target among distractors and make a response regarding its orientation. The target is defined as a unique shape, and is sometimes shown with a salient distractor.

Primary outcomes

  1. First fixation duration during visual search

    Time frame: During visual search task

    This measure is the average first fixation duration during the visual search task. Possible scores are a minimum of 50 ms with an undeterminable positive number of ms as a maximum. This measure indicates the duration of processing before the first eye movement decision.

  2. Fixation count during visual search

    Time frame: During visual search task

    This measure is the count the average number of eye movements participants made per trial during the visual search task. Possible scores range from a minimum of 0 to approximately 40 eye movements, given the time available. This measure indicates the amount of active exploration of the display during search.

  3. Stop signal reaction time

    Time frame: During inhibitory task

    Stop signal reaction time is a quantitative estimate of how long participants take to successfully inhibit a planned eye movement. Possible scores range from a minimum of 0 ms to a maximum of about 600 ms. Low scores indicate strong inhibitory ability and high scores indicate weak inhibitory ability.

  4. Useful field of view thresholding

    Time frame: During attention task

    Performance in a thresholding task indicates participants ability to detect a briefly presented target among distractors with 80% accuracy. Contrast of the displays varies until performance meets achieved level. Possible scores range from 0 to 100% contrast. Lower contrast indicates better information accrual, while higher contrast indicates worse.

  5. Useful field of view dual task performance

    Time frame: During attention task

    Performance in a dual task indicates participants ability to spread attention across the visual field. Possible scores range from 0 to 100% accuracy. Higher performance indicates better information accrual, while lower performance indicates worse.

  6. Oculomotor capture by salient distractor

    Time frame: During visual search task

    in the attentional capture search task, a measure of how often participants look at the salient yet irrelevant distractor will be calculated.

Secondary outcomes

  1. Average fixation duration during visual search

    Time frame: During the visual search task

    This measure is the average fixation duration across all fixations in a trial during the visual search task. Possible scores range from a minimum of 50 ms to approximately 500 ms. This measure indicates the average duration of processing before a saccadic decision is made.

Study contacts

Contact information is provided by the study sponsor or research team.

Carly J Principal Investigator, PhD

CONTACT

[email protected]

303-315-7068

Ryan V Postdoctoral Fellow, PhD

CONTACT

[email protected]

303-315-7065

Sponsors and collaborators

Lead sponsor

University of Colorado, Denver

Other

Collaborators

  • National Eye Institute (NEI)

Registry information

Official study title

Contributions of Attentional and Inhibitory Functioning to Saccadic Decisions

Important dates

Study start
2024
Primary completion
2026
Study completion
2026
First posted
Sep 19, 2024
Registry last updated
Feb 20, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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