Section 4: Teaching to determine crossable gaps --
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USING VISION
to determine when it is "clear to cross"
Visual tasks for crossing streets
So far, we've talked about listening for vehicles to identify when it's clear to cross.
Now we're going to consider the task of looking for vehicles to determine if there is a gap in traffic long enough to cross.
Basically, there are two visual tasks for crossing streets IF you are in a Situation of Confidence:
1. Watch for "all clear:"
This task involves looking to make sure nothing is coming.
2. Determine if gaps in traffic are long enough:
Students who can see vehicles approaching in the distance may be able to determine whether those vehicles are far/slow enough to allow time to cross before they arrive.
Assessment and training of this skill may be just as important as the skill of making sure it's "clear to cross."
Lack of this skill may be what caused the deaths of Dick and Lorraine Evensen at the crossing shown in the photo to the left,
and research suggests that some people with visual impairments think that their ability to judge gaps in traffic is better than it actually is (Cheong, Geruschat, and Congdon, 2008).
But WAIT! There's MORE -- and it's critically important!
Glancing or scanning in each direction:
Unlike listening for vehicles, which can be done from both directions at once, people can look for vehicles in only one direction at a time (unless they have two heads like the woman in the photo!).
This means that both of the visual street-crossing tasks (watching for "all clear;" and determining if gaps in traffic are long enough) must be done while looking from side to side to make sure there is a crossable gap in both directions.
This will all be covered on the next few pages, starting with learning how to look for vehicles effectively.
Cheong, A.M., Geruschat, D.R., Congdon, N. (2008). "Traffic gap judgment in people with significant peripheral field loss." Optometry and Vision Science, American Academy of Optometry.
Vol 85, No 1: pp. 26-36