This seems to be the standard term in the literature (NB not "link" or "connection") - see, for example, the following links (all academic papers, to match the source):

"a conditioned Pavlovian fear response that depended upon a learned association"
(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2966824/)

"the learned association between CS and US was still present after extinction"
(http://www.indiana.edu/~p1013447/dictionary/extinct.htm)

and to connect this to the German:

"Classical conditioning is an example of a learned association"
(https://en.wikipedia.org/wiki/Association_(psychology))

which seems, to me, very similar to this:

"Für die Konditionierung (Lernverknüpfung) gibt es 4 verschiedene Möglichkeiten:"
(https://www.hundeschuhle.de/2018/12/05/clicker-markerwort/)



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Note added at 28 mins (2019-03-15 21:26:14 GMT)
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@Asker - all the info about dog-training had me foxed (for a suitably animal-based metaphor!) too, until I realised that the basic psychology under discussion was largely the same!