Appendix B: Subject Instructions
Subjects were given the following instructions on the first
day of testing. On subsequent days they received and signed an
abbreviated version.
What's going on?
I am running an experiment that looks at how people see things
that are far away (visual depth perception). I'd be happy to tell you
more about the experiment and what I'm trying to do when you are done
being a subject. For obvious reasons, I can't tell you anything now.
I could also demo some of the stuff around the lab for you after your
final trial, if you're interested.
What do I have to do?
A scene of (roughly) an ocean and sky will be presented to
you. Your basic task is to guess how far away you think the stimulus
object is in the scene you will see. You should make a guess based
upon how many feet you think the object is.
It's important to realize where you are observing the scene
from. Your viewpoint is 31 feet off the floor and the object you are
looking at is 15 feet tall. Imagine standing on the 3rd floor of a
building and looking out a small window at a lamppost some distance
away. This is equivalent to the scene you will be presented with in
the experiment.
What will happen?
You will be viewing the scene inside our
head-mounted-display(HMD) This display is somewhat expensive and
fragile, so please be careful. It is very important that you adjust
the HMD to be as clear and comfortable as possible. There is a small
area inside the HMD in which the image should be sharp and crisp, try
to get the HMD adjusted so that this occurs. I'll help you to do
this, don't worry.
You will be giving responses via a voice recognition
system. After you see the object, you should press the push-to-talk
button and say how far away you think the object is. After you make
your guess, a brief pause will occur and another scene will be
presented. On some of the trials, the computer will tell you what the
right answer was. A number will appear after you make your guess;
this was the correct answer for that trial. You will have a moment to
absorb this number before a short pause and the next trial.
How should I guess?
Try to be as exact as you can with your guesses. Try to avoid
generalizing or estimating; try to be as exact as you think you can be
in your guesses (i.e. avoid "five thousand" for a set of trials where
that's roughly correct; "four thousand five hundred and ten" would be
better). Your responses should be numbers from 1 to 99,999. You will
be trained to use the voice recognition system before running the
actual experiment. A specific grammar is used with the system (you
can't say "fifteen hundred" for 1500, you have to say "one thousand
five hundred").
It might be really hard to see the stimulus object in some of
the trials. Make the best guess you can. If you can't see the
object, you can respond with "I can't see that." This stuff is
elucidated in the voice recognition training.
What if I screw up?
You can't screw up. If you stumble with the response you are
giving, don't worry, I'm listening too, and will catch errors. If you
feel like you aren't doing very well, don't worry, it's fine.
How long do I have to do this for?
You will be given 3 breaks to help you remain focused. The
first and third breaks are short, 2 minute, breaks. You can remove
the HMD and relax, but you should stay in the lab. The middle break
will be longer; you can wander around, get a soda, use the restroom,
relax for 10 minutes. Please don't disappear for longer, it's
important to only have a 10 minute break. The total time for running
the experiment and filling out the forms should be a little under 2
hours.
It's a good idea to try to keep up a good pace of
responding. Don't let your mind wander, but take the time you need to
feel good about your response.
What if I start feeling bad or need to stop?
If you start feeling nauseous or super-uncomfortable, let me
know immediately. I will be in the room during the test and can help
you with any problems you might be experiencing. If for some reason
you feel that you cannot continue the tests (nausea, bad headaches,
etc.), that's okay and you will be paid for your time. Unfortunately,
if you experience nausea or headaches, you will be excused from the
experiment. Not many people experience "simulator sickness," so don't
be worried, but do speak up if you start feeling really
unpleasant.
I have read the subject information material and I have been
familiarized with the experimental procedures. I am agreeing to
participate in these experiments of my own free will. I understand
that I am completely free to end my participation at any time for any
reason.
Name (print):
Signed:
Date:
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