The Effects of Stimulus Variability in Natural Visual Scenes
Phase: NA
Conditions: Visual Perception
Sponsor: University of Pennsylvania

 
  
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Official Title  
The Effects of Stimulus Variability in Natural Visual Scenes 
 
NCT Number 
NCT05004649 
 
IRB Approval Date 
Dec 7, 2018 

 
  
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Color Constancy, EY 10016 
David H. Brainard 
Protocol Summary 
 
Subjects 
 
The subject population for these studies will be volunteers compensated either with cash 
or course credit. Subjects will be drawn primarily from the University community and 
obtained through word-of-mouth, online, or other informal advertisement, or recruited 
through the Psychology department’s course subject pool.  Online advertising may 
include a subject recruitment system managed through Penn's Center for Cognitive 
Neuroscience.  Some of the experiments require that the subject have normal color vision 
and/or visual acuity, and for some experiments we will screen for native language or 
handedness.  The principle investigator and other members of the lab may also participate 
as unpaid volunteers. 
 
Procedures 
 
The subject will view visual stimuli that consist of illuminant objects, are presented on a 
computer-controlled monitor, or are presented using a specialized optical system.  
Radiometric measurements will be used to ensure that none of the apparatus can 
stimulate the eye with unsafe levels of illumination.  Where appropriate, filters will be 
inserted in the optical path to protect the eye from infrared and/or ultraviolet rays.  In 
some experiments, the subject will be asked to clench a dental impression or place his/her 
head in a chin rest to minimize head movements.  The subjects’ task will be to make a 
response indicating some aspect of what he or she perceives.  Often this will involve 
pressing keyboard keys or turning knobs to adjust the color of one of the stimulus objects 
until its appearance matches that of another object or of a learned memory color. 
Sometimes judgments of other aspects of the percept may be required and sometimes 
other response modes will be used (e.g. joystick, verbal response.)  In some experiments, 
subjects' eye movements will be monitored and recorded while they perform the tasks.  
Experimental sessions will be one hour or less in duration. Individual subjects will 
typically participate in many sessions on an ongoing basis. 
 
Subjects will typically be screened for normal vision using standard methods (e.g, 
Snellen eye chart, pseudo-ischromatic color plates) or short preliminary experiments 
using the methods described above. 
 
In some cases, subjects will be asked to complete a series of brief questionnaires after the 
experiment is completed. Examples include the following four questionnaires: (1) a 
general survey about the experiment in which subject is asked to report about the 
strategies they used to complete experimental tasks, (2) Art Experience Questionnaire 
(AEQ), (3) Vividness of Visual Imagery Questionnaire 2 (VVIQ2) and (4) Verbalizer-
Visualizer Questionnaire. Administration of all 4 questionnaires may take up to 60 
minutes and may be done in a separate debriefing session. Other similar questionnaires 
may be administered should they be relevant for specific experiments. 
 

 
  
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Risks 
 
There are no known risks involved with participation in these studies. Subjects may 
experience boredom during the experiment. 
 
Confidentiality 
 
Information identifying individual subjects will be kept only on a subject data sheet (copy 
enclosed).  This sheet will connect each subject to a randomly chosen letter/digit code 
(aka code number) and will be kept in confidence by the PI and laboratory personnel, 
either on paper in a locked cabinet or in an encrypted computer file.  All other research 
records will identify individual subjects only by the code.  The code may also be used to 
identify individual subject data in published reports and professional presentations. Data 
from this study may be reported in scientific presentations open to the public and 
publications available to the public.  Subjects will not be identified in such presentations 
or publications by name; single subject data may be presented but will be identified only 
by code number so people cannot tell who participated nor which data are from whom. 
Data collected in this study may also be released to the general public via a fully open 
database that may be accessed using the Internet. In the data that is shared with the 
general public, subjects will again only be identified by code number, so people who 
access the data cannot tell that who participated nor who the data are from. No 
identifying information will be shared with the general public or anyone who is not 
laboratory personnel. Additionally, the data and samples contained within research 
records from this study might be used for other, future research projects in addition to the 
current study. These future projects can focus on any topic, and might have goals 
unrelated to those of this study. If a subject withdraws from the study we will cease data 
collection. However, any data and research results already collected may be used in 
presentations/publications, shared with the general public, or with other investigators. 
Once data has been presented, published, shared with the general public or other 
investigators it cannot be destroyed, withdrawn or recalled. Subjects must be willing to 
have data shared in this way in order to participate in this study. If they are not willing to 
allow data from you to be shared in this way, they cannot participate in this study. 
 
Consent 
 
The experimental procedure and general purpose of the experiments will be explained to 
the subject before participation begins, as well as the expected duration of subject 
participation. The subject will be asked to read and sign the attached consent form.  
Subjects will be free to withdraw from the experiment at any time.  Subjects recruited 
from SONA-systems or other for-credit subject pools will be informed that they may 
complete a research paper or participate in a different experiments to receive credit.  
After subjects have finished participating in experiments, they will be given an 
opportunity to ask questions about specific experimental hypotheses and results. 
 
Benefits 
 

 
  
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The experiments are designed to improve our understanding of how we perceive object 
color, with particular emphasis on the role played by early visual mechanisms.  
Individual subjects may take an interest in the research and its findings. 
 
Payment 
 
Subjects will be paid for participation in this study at an hourly rate of $10/hour, or will 
receive course credit.  They will be paid/receive credit for the time they actually 
participated, whether or not they complete the full experiment.  In some paid 
experiments, there may be a bonus payment that depends the degree to which the 
subject’s visual judgments are objectively correct.  The experimenter will review any 
such bonus with the subject as part of the instructions for the particular experiment.  The 
bonus will not exceed $10/hour. 
 
Risk-Benefit Ratio 
 
The risks are minimal or non-existent.  Potential benefits are positive, and thus outweigh 
the risks.