In this experiment, your task will be to find matches for various objects.  At the start of 
each trial, the shutter will open and you will see two cards: one on the right and one on 
the left.  The cards are grayscale, potentially ranging from black through various grays to 
white, and have nothing printed on them.  They may be at different slants and seen under 
different illuminants.

Your task is to match the gray of each card to a sample on the palette to your left.  The 
samples on the palette range from dark to light, and each is numbered, with "1.0" being 
the darkest and "10.0" being the brightest.

To make your response, you will use the slider in front of you. The screen in the middle 
will have the number corresponding to the current slider position.  Sliding the bar to the 
right will increase the value, while sliding the bar tot he left will decrease the value. 
Although two cards will be visible, you will complete one match at a time.  An arrow on 
the screen will direct you to the card to match to the palette.

If, when making your match, you find that the card is darker than the darkest patch on the 
palette, slide the bar all the way to the left to rate the card as darker than 1.0.  On the 
other hand, if the card is lighter than the brightest patch, slide the bar all the way to the 
right to rate the card as lighter than 10.0.

Before you started this experiment, we had you examine wooden blocks and notice that 
there can be a difference between how much light appears to reflect from objects on the 
one hand and how the objects are painted on the other.

[A] In this experiment, we would like you to make a match based on the reflectance of 
the card and palette sample, rather than the amount of light that appears to reflect from 
them.  That is, imagine the card was placed side-by-side with the palette, both at the same 
slant and under a common illuminant, and make your match based on how they would 
look if they were viewed in that configuration.

[B] In this experiment, we would like you to make a match based on how much light 
appears to reflect from the card and palette sample, and not the reflectance of the 
card/sample or how you think they would look if they were presented side by side.

It is now time to begin the experiment.  If you have any questions at this point or any 
time during the experiment, please ask the experimenter.  Information regarding the 
current trial number and total number of trials will be visible on the upper left corner of 
the monitor.