"The Scientific Reason Parents Are Always Mixing Up Their Kids' Names"

"According to a review in Memory and Cognition that studied the phenomenon of misnaming, it tends to occur among people that you have an equally close relationship with. From the 1,700 participants, most of those who called someone by the wrong name were moms, and their mix-ups typically included all people they love. "Overall, the misnaming of familiar individuals is driven by the relationship between the misnamer, misnamed, and named," the study states."

http://www.popsugar.com/moms/Why-Moms-Call-Kids-Wrong-Names-43221453?utm_medium=facebook&utm_source=post&utm_campaign=moms

Posting because I do this to my friends All The Time, and this is how I explained it to myself - so I'm glad to see I'm correct. 

I think more generally, though, this phenomenon could be defined as: when we put two people in the same strongly-defined category, we will be likely to mix up their names.