Trial Outcomes & Findings for Studying the Effects of Natural Visual Scene Changes on Typical Adult Visual Perception (NCT NCT05004649)
NCT ID: NCT05004649
Last Updated: 2023-05-10
Results Overview
A psychophysical task will be used to measure participants' ability to discriminate the horizontal position of the central object that is presented within the context of background objects in a natural visual scene. The task will be a two-interval forced choice task that presents one stimulus per interval. The task will be to determine whether, compared to the central object presented in the first interval, the central object presented in the second interval is to the left or to the right. The horizontal discrimination threshold is reported below as a function of noise in the stimulus. The horizontal discrimination threshold is defined as the minimum distance in which two stimuli can be recognized as spatially separate in the horizontal plane. The lower the horizontal discrimination threshold the smaller the difference between two stimuli in the horizontal direction to be perceived as distinct.
COMPLETED
NA
19 participants
Approximately 3 weeks
2023-05-10
Participant Flow
Prior to the experiment, participants will be interviewed and fill out a survey. They will be excluded prior to the experiment if their best-corrected visual acuity is worse than 20/40 in either eye or if they make any errors on the Ishihara plate test. Participants will be excluded after the conclusion of their first session if their horizontal position discrimination threshold in the control condition is higher than a maximum value of 0.6 degrees of visual angle.
Participant milestones
| Measure |
Healthy Participants
It is expected that participants will complete this pilot experiment in six sessions. The first session will include participant enrollment procedures as well as familiarization trials and will last approximately one and a half hours. The second through sixth sessions will last approximately one hour each.
For the first session only, the participant will begin with 30 familiarization trials. The familiarization trials will comprise, in order: 10 randomly selected easy trials, 10 randomly selected medium-difficulty trials, and 10 randomly selected trials from all possible position-change comparisons. Data from the familiarization trials will not be saved.
A "block" of trials will consist of 22 trials. The trials within a block will be run in randomized order. A block will be completed before the next block of trials begins. There will be 14 iterations of a block, for a total of 308 trials. This set of 308 trials will make up a single "noise level". A single session will consist of three noise levels: Noise Level 0, Noise Level 1, and Noise Level 2. The trials for each noise level will be divided into two "runs" (154 trials per run). Thus, each run will comprise a single noise level. The six runs will be run in random order per session. Each run will be separated by a break that lasts at least one minute and will end when the participant indicates that they are ready. Across all six runs, there will be a total of 924 trials.
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|---|---|
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Overall Study
STARTED
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19
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Overall Study
COMPLETED
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11
|
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Overall Study
NOT COMPLETED
|
8
|
Reasons for withdrawal
| Measure |
Healthy Participants
It is expected that participants will complete this pilot experiment in six sessions. The first session will include participant enrollment procedures as well as familiarization trials and will last approximately one and a half hours. The second through sixth sessions will last approximately one hour each.
For the first session only, the participant will begin with 30 familiarization trials. The familiarization trials will comprise, in order: 10 randomly selected easy trials, 10 randomly selected medium-difficulty trials, and 10 randomly selected trials from all possible position-change comparisons. Data from the familiarization trials will not be saved.
A "block" of trials will consist of 22 trials. The trials within a block will be run in randomized order. A block will be completed before the next block of trials begins. There will be 14 iterations of a block, for a total of 308 trials. This set of 308 trials will make up a single "noise level". A single session will consist of three noise levels: Noise Level 0, Noise Level 1, and Noise Level 2. The trials for each noise level will be divided into two "runs" (154 trials per run). Thus, each run will comprise a single noise level. The six runs will be run in random order per session. Each run will be separated by a break that lasts at least one minute and will end when the participant indicates that they are ready. Across all six runs, there will be a total of 924 trials.
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|---|---|
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Overall Study
Eligibility Criteria - Threshold
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4
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Overall Study
Lost to Follow-up
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1
|
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Overall Study
Withdrawal by Subject
|
2
|
|
Overall Study
COVID-19
|
1
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Baseline Characteristics
Studying the Effects of Natural Visual Scene Changes on Typical Adult Visual Perception
Baseline characteristics by cohort
| Measure |
Healthy Participants
n=11 Participants
Participants will be invited to volunteer to participate in this study. Participants will provide informed consent. To ensure that the participants meet the eligibility criteria, prior to the experiment, they will be interviewed and they will fill out a survey. Also prior to the experiment, they will be screened for visual acuity using a Snellen eye chart and for color deficiencies using the Ishihara plate test. They will be excluded prior to the experiment if their best-corrected visual acuity is worse than 20/40 in either eye or if they make any errors on the Ishihara plate test.
For enrolled participants, their threshold for horizontal position discrimination (in a control condition without any task-irrelevant variability) will be calculated based on their performance on the experimental task during their first session. Participants will be excluded after the conclusion of their first session if their horizontal position discrimination threshold in the control condition is higher than a maximum value of 0.6 degrees of visual angle, and participants excluded at this point will not participate in any further experimental sessions. If very few enrolled participants satisfy this criterion, then this maximum threshold value for participant inclusion will be increased. In the case that the maximum threshold value for inclusion is increased, participants that had been previously excluded will not be re-included in the experiment posthoc.
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|---|---|
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Age, Continuous
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31 years
n=5 Participants
|
|
Sex: Female, Male
Female
|
7 Participants
n=5 Participants
|
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Sex: Female, Male
Male
|
4 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Hispanic or Latino
|
1 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Not Hispanic or Latino
|
10 Participants
n=5 Participants
|
|
Ethnicity (NIH/OMB)
Unknown or Not Reported
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
American Indian or Alaska Native
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Asian
|
4 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Black or African American
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
White
|
6 Participants
n=5 Participants
|
|
Race (NIH/OMB)
More than one race
|
0 Participants
n=5 Participants
|
|
Race (NIH/OMB)
Unknown or Not Reported
|
1 Participants
n=5 Participants
|
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Visual Acuity Correction
Glasses
|
6 Participants
n=5 Participants
|
|
Visual Acuity Correction
Contacts
|
1 Participants
n=5 Participants
|
|
Visual Acuity Correction
Unaided
|
4 Participants
n=5 Participants
|
PRIMARY outcome
Timeframe: Approximately 3 weeksPopulation: Analysis is of the 10 naive subjects who completed the study, one completed subject was an experimenter for the study and thus is excluded from analysis.
A psychophysical task will be used to measure participants' ability to discriminate the horizontal position of the central object that is presented within the context of background objects in a natural visual scene. The task will be a two-interval forced choice task that presents one stimulus per interval. The task will be to determine whether, compared to the central object presented in the first interval, the central object presented in the second interval is to the left or to the right. The horizontal discrimination threshold is reported below as a function of noise in the stimulus. The horizontal discrimination threshold is defined as the minimum distance in which two stimuli can be recognized as spatially separate in the horizontal plane. The lower the horizontal discrimination threshold the smaller the difference between two stimuli in the horizontal direction to be perceived as distinct.
Outcome measures
| Measure |
Noise Level 0
n=10 Participants
For Noise Level 0, there will not be any changes to the background objects (the branches and leaves). Noise Level 0 will be the control condition and will be used to determine the participant's threshold for discriminating the horizontal position of the central object without any task-irrelevant stimulus noise. Noise Levels 1 and 2 will be used to determine the participant's threshold for discriminating the horizontal position of the central object in the presence of task-irrelevant stimulus noise.
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Noise Level 1
n=10 Participants
Noise Level 1 will consist of task-irrelevant noise in a single task-irrelevant feature:
rotation. A task-irrelevant rotation amount will be applied to each stimulus separately.
For each stimulus, a single rotation amount will be drawn randomly from a pool of 51 rotation amounts, and the background objects in the stimulus will all be rotated by that rotation amount. The rotation amount will be drawn separately (randomly with replacement) for each of the two stimuli presented in a trial (the reference position stimulus, and the comparison position stimulus). The pool of 51 rotation amounts will comprise: one rotation amount of zero (no change to the background objects), 25 equally spaced rotation amounts in the clockwise direction, and 25 equally spaced rotation amounts in the counterclockwise direction.
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Noise Level 2
n=10 Participants
Noise Level 2 will consist of task-irrelevant noise in two task-irrelevant features: rotation and depth. For Noise Level 2, there will also be a pool of 51 noise amounts, but each noise amount in the pool will consist of both a rotation amount (the same 51 rotation amounts as in Noise Level 1) and a depth amount. There will be 51 possible depth amounts (one depth amount of zero, 25 equally spaced depth amounts in the position direction, and 25 equally spaced depth amounts in the negative direction). For the Noise Level 2 pool of 51 noise amounts, one of the noise amounts will consist of a rotation amount of zero and a depth amount of zero. For the remaining 50 noise amounts in the pool, each of the remaining 50 rotation amounts will be randomly assigned (without replacement) to one of the remaining 50 depth amounts. From this Noise Level 2 pool of 51 noise amounts, a single noise amount will be randomly drawn (with replacement) for each of the two stimuli in a trial separately.
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|---|---|---|---|
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Psychophysical Measurements of Horizontal Discrimination Threshold
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.30962 degrees of visual angle
Interval 0.17429 to 0.54115
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.35002 degrees of visual angle
Interval 0.22652 to 0.65267
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.32849 degrees of visual angle
Interval 0.20195 to 0.6415
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Adverse Events
Healthy Participants
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place