Instrument myopia

Hi

Here in New Zealand we use binocular optical devices to measure the
vision for the drivers licence.

When these devices were introduced there was talk in the press (from
opticians) that some people with a highly emotional nature would not
be able to get an accurate reading using the devices.

I found that myself and a friend of mine could not see well thru these
devices even though the target was well illuminated and covered a
considerable amount of the visual field. We both wore our full
strength glasses and/or contact lenses. I suppose I can agree that
both my friend and I are highly emotional.

It is my understanding that all optical devices that are placed in
front of a person are compensated for instrument myopia, because
although the eyes are pointing forwards, the mind still believes the
object is close to the observer.

Does anybody have any specific knowledge about instrument myopia?

Does anybody have any more information to support the claims in the
press (reported to be by opticians) that certain people would not be
able to get an accurate measurement from these devices.

Is there any research on this?

Thanks

Andrew