Study demonstrates universal human ability for logarithmic spacing of numbers

"Summary: The ability to map numbers onto a line is universal. But for an Amazonian tribe, this mapping is not linear but logarithmic. The finding illuminates both the nature and the limits of the human predisposition to measurement, a foundation for science, engineering, and much of our modern culture."

The original title ("Slide Rule Sense: Amazonian Indigenous Culture Demonstrates Universal Mapping Of Number Onto Space") is too long for HN and doesn't mention the (to me) most interesting thing of it being logarithmic; so I came up with this title but would welcome a suggestion of a better one.

I read the article, but it didn't answer some questions I had.

Did the lines used in the mapping have defined lengths, and was it accounted for that the subjects could have given a wider berth for initial numbers before realizing they were running out of space?

How close was each result to true logarithmic space?

I am inclined to believe the conclusion because many of our senses (and thoughts themselves) are rooted in logarithmic mappings, such as a higher sensitivity to lower frequency sounds and light conditions, logarithmic pain tolerance, adaptation rates, etc. but I would love to have more information about the results.