T3D vernier acuity

[john bercovitz <bercov@xxxxxxxxxxx>]

I was thinking about vernier acuity which is the ability 
to align lines to each other such as on vernier calipers.  
Since vernier acuity and stereo acuity probably use much 
the same machinery, and since stereo acuity is used to 
check the relative positions of vertical edges, I was 
wondering if a test has been done to see if vernier acuity 
is just as accurate vertically as horizontally.  In other 
words, can you align

this
        __ __


just as well as you can align this

          |
          |

Anyone know?

Thanks,
John B


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