The confusion matrix is a fundamental term in machine learning. However, that name itself is a bit, well, confusing. I tried to trace its origin but I'm not sure I'm correct, and I'd like to hear what others know.
The term became popular in the ML community thanks to Kohavi and Provost at 1998.
However, already at 1971 Townsend wrote a paper discussing it. The paper discusses and experiment in which the 26 English alphabet letters (stimuli) are presented to a subject that should present reply with the same letter (reaction). The confusion is a 26 by 26 matrix with the probability of each reaction to each stimulus. This explains the name (the matrix of the subject confusion) and matches the use in machine learning today.
I found even earlier references to the term confusion matrix, starting at 1953 using Google books, but the text wasn't available. It seems that there are even earlier reference to the term in psychology since it is used as a known phrase.
Is the origin of confusion matrix indeed in psychology and due to such usage? What else is known about the term?
1955 Journal of applied psychology, Volume 39
American Psychological Association, 1955