Without context... 選んだこと would either mean
- The thing I chose
- The event of choosing
If the verb is intransitive, it will yield the 2nd meaning. Also the "thing" here is something intangible and abstract.
So I would like to have some tips in distinguishing both.
A : 昨日のパーティは楽しかった
B : 選んだことは面白くなかったのに
Does B imply that "choosing the party was not interesting" or "the event that (I) chose was not interesting"?