I’ve got a big doubt regarding this topic. I know that a verb expressing observation or perception can be only followed by a noun and a participial phrase (-ing).
But I’ve come across that (quoted from an English grammar book): ‘A verb expressing observation/ perception can be also followed by a noun and a base verb form. The suffix -ing is deleted from the verb. There is no difference in meaning.’
Here are some examples:
-
We felt the temperature rising. - We felt it rise.
-
We observed the doctor doing open-heart surgery. - (no base-form equivalent)
I don’t quite get it. Why the first sentence could work with a bare infinitive and second no? Is the bare infinitive actually possible with an observation/perception verb? Could someone enlighten me on this matter, please?
With many verbs, both forms are possible but with slightly different meanings: the ‘-ing’ form is durational (it suggests the action itself rather than the completed act) and does not make clear whether the entire process was perceived, while the bare infinitive form indicates that it was perceived to completion (it suggests a completed act):
I saw a man crossing the street. (I did not necessarily see him reach the other side, but I watched his activity.)
I saw a man cross the street. (I watched him until he reached the other side; I saw the completed act of ‘street crossing’.)
This is the case for your #1. For your #2, ‘observed…do’ sounds odd and would probably not be used because the verb ‘observe’ so strongly suggests the durational activity rather than the completed act.