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"An event with probability ${\displaystyle \Pr(x)=0}$ (an impossible event) has an information content of ${\displaystyle \mathrm {I} (x)=-\log _{b}(0)}$ which is undefined but is taken to be ∞ by convention."

Is this the best justification for this? It is also true that ${\displaystyle \lim _{x\to 0}-\log _{b}(x)=\infty }$, which might be a better way to put it: it isn't simply convention alone. Dralimf (talk) 15:09, 13 September 2025 (UTC)[reply]

It's hard to trace back terms to their earliest use, when they may come from different fields, so I'm adding this talk topic for any discussion around the origin of this term.

Currently the text (incorrectly) claims the term was first introduced in the 1961 Thermodynamics and Thermostatics textbook [1] by Myron Tribus. Tribus' text does indeed define surprisal, but doesn't claim to be introducing it as a novel term, and there are a number of earlier publications which use the term, so this isn't correct.

As far as I can tell, the earliest reference for the term surprisal seems to be in a Edward W. Samson's 1951 report "Fundamental natural concepts of information theory" (AFCRC Report No. E5079), reprinted in 1953 in the journal ETC: A Review of General Semantics, 10 [2].

Samson's report is referenced as the origin of the term 'surprisal' in the first chapter of Fred Attneave's Applications of information theory to psychology (Henry Holt. 1959) [3].

I will update the text to reflect this. Jimpaz (talk) 23:15, 13 February 2025 (UTC)[reply]