Left vs. right

Chapter 12 endnote 31, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

[Dogs are] more relaxed when they view movies of right-wagging tails and more stressed for left-wagging tails, as measured by heart rate and other factors.

Personally, I’ve never had much confidence in these kinds of laterality findings, because laterality findings in humans are all over the place. Sometimes they replicate, sometimes they don’t, and sometimes they flip (a finding that was on the right side appears on the left and vice versa). But perhaps the laterality findings are more consistent in dogs and there is some deeper meaning in these findings.