Some dogs have a strong preference on right/left. I've known at least six dogs that will only shake hands with their left paw.

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kokanee 8 hours ago | parent | next [-]

Yes, and also the presence of a window fan on that side is a big deal because the selection is based on scent. In my experience dogs appear to "like" a scent based on how strong it is, not necessarily how it is "flavored" (for examples, dogs can behave as if they love the smell of poop or skunk spray, but it's actually the powerful sensory information that they're reacting to, not a culinary desire). It seems possible to me that the dog is choosing whichever scent is more powerful.

	▲	wespiser_2018 7 hours ago \| parent [-]
		If I repeat this experiment, I'll be a lot more careful about that, or also alternate which direction I'm standing in. I didn't realize R/L preference was biased until I did the data analysis, and during the trials he was picking from both hands often enough that I perceived it as roughly 50% depending on the treats!

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RataNova 8 hours ago | parent | prev [-]

Yep, I have seen dogs that clearly have "a side" for certain habits, even if it is not obvious whether it is paw preference, training, comfort...