Edit: Why the downvotes? Is my question probing at something people find incompatible with their ideology?
> Chapman always sent two vehicles from opposite sides of the road during those trials — either a car and a car, or a car and a motorcycle. Then, right after the participant pulled out, he would stop the test and ask them to use a laser pointer to point where the oncoming vehicle(s) had been on the screen.
> What Chapman found was that, every once in a while, there were instances where the driver had failed to report seeing the motorcycle and the car, even though an eye tracking device showed that they clearly looked at the oncoming vehicles. But he also found that participants were much more likely to miss the motorcyclist than the car driver.
Later when the motorcycle is only in peripheral vision, it's quite likely that constant bearing decreasing range contributes to the motorcycle being forgotten.
But this doesn't change the thesis, which says that the motorcycle is more likely to be forgotten because it's smaller. Because it's smaller, it's more likely to have the constant bearing decreasing range error, which means it's more likely to be forgotten.
To summarize: the effect may be useful in understanding why this happens, but doesn't change the thesis.