Visual Mechanisms of Intermediate Distance Space Perception During Self-motion
Trial Snapshot
- Phase
- Not Applicable
- Status
- Recruiting
- Sponsor
- University of Louisville
- Enrollment
- 180
- Locations
- 2
- Primary Endpoint
- Visual mechanisms of intermediate distance space perception (distance) before and after self-motion
Study Overview
Brief Summary
The ability to judge the locations of various objects from oneself during self-motion in the intermediate distance range (~2-25m) is crucial for successful performance of activities of daily living, such as walking and driving. However, little is known about the mechanisms of visual space perception involved in judging distance, the focus of this project, in the planning and/or execution of self-motion in the natural 3D environment. The theoretical knowledge to be gained from this project will contribute to the scientific literature and provide insights into how eye and neurological defects could impair visual space perception, wayfinding, and mobility.
Detailed Description
Every day human subjects rely on their vision to judge the absolute distances of objects around them to plan and guide their actions, such as walking and driving. This, way-finding, process of ascertaining one's position and planning for possible routes of actions cannot be accomplished without reliable perception of visual space in the intermediate distance range (~2-25m from the observer). Thus, the broad long-term objective of this project is to uncover the mechanisms underlying intermediate distance space perception that supports distance judgment.
Yet, less is known about the underlying mechanisms of intermediate distance space perception compared to those of near space perception (<2m). Moreover, extant knowledge is predominantly obtained from testing static observers, making it difficult to generalize to the more common situation where observers plan and execute self-motion. The latter situation is more complex because self-motion is accompanied by retinal image motion of static objects in the surrounding environment, potentially requiring the visual system to simultaneously track the locations of all objects in the environment. The visual system also requires more processing capacity because it has to simultaneously compute the visual space representation, explore the environment, implement motor controls, etc. Clearly, both challenges - coding complexity and capacity limitation - could pose as potential threats to our ability to efficiently judge absolute distances and implement actions. This project hypothesizes the visual system overcomes both challenges by: (a) spatially updating the moving observer's position using an allocentric, world-centered spatial coordinate system for representing visual space, and (b) use spatial working memory (spatial-image) during spatial updating. The investigators will examine both hypotheses in three specific aims.
Aim 1: Investigate the implementation of the allocentric, world-centered spatial coordinate system
Aim 2: Investigate the factors affecting the spatial updating of visual space
Aim 3: Investigate the role of spatial-image memory in visual space perception
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Basic Science
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 40 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Adults (up to 40 years of age)
- •Children (18 years and older)
- •Normal, or corrected-to-normal, visual acuity (at least 20/20)
- •Stereo acuity (<20 arc sec).
Exclusion Criteria
- •Self-reported history of visual and eye diseases
- •Physical movement restrictions.
- •Vulnerable populations such as pregnant women will be excluded owing to the extensive time commitment required of the subjects.
Arms & Interventions
Visual scences
Lit target locations in visual environment will be varied and subjects' perceived locations will be measured.
Intervention: Visual Stimuli for Space Perception (Other)
Outcomes
Primary Outcomes
Visual mechanisms of intermediate distance space perception (distance) before and after self-motion
Time Frame: During procedure, an average of 10 sec.
Subjects will judge perceived distances (cm) of test targets from themselves before self-motion to establish a baseline measure. Subjects will then undergo self-motion for an average of 10 sec, and stop at a predetermined location. Then subjects will again judge the perceived distance (cm) of test targets after the self-motion. The change in perceived distance (cm) from baseline will reveal if their perception is affected by environmental factors, internal perceptual process and/or cognitive process.
Visual mechanisms of intermediate distance space perception (height) before and after self-motion.
Time Frame: Druing procedure, an average of 10 sec.
Subjects will judge perceived heights (cm) of test targets relative to the floor or ceiling before self-motion to establish a baseline measure. Subjects will then undergo self-motion for an average of 10 sec, and stop at a predetermined location. Then subjects will again judge the perceived height (cm) of test targets after the self-motion. The change in perceived height (cm) from baseline will reveal if their perception is affected by environmental factors, internal perceptual process and/or cognitive process.
Secondary Outcomes
No secondary outcomes reported
Investigators
He Zijiang
Professor
University of Louisville