Imagine that you want to describe an experience. You want to talk about how you perceived something – in other words, what you saw, heard, or felt.

In our report today, we will explore the grammar of perception.

Specifically, we will explore what grammar experts might call "verbs of perception." These are words that describe actions related to our senses – seeing, hearing and listening, for example.

Betty Azar is an expert on English grammar. In her book Understanding and Using English Grammar, she notes that English speakers often use verbs of perception before two other verb forms: the simple form and the form ending with –ing.

Similar meaning

Azar adds that the two verb forms that follow verbs of perception can sometimes have a similar meaning.*

As an example, let us consider a line from a famous movie -- 2001: A Space Odyssey. In the film, a computer named HAL says the following words:

"Dave, although you took very thorough precautions in the pod against my hearing you, I could see your lips move."

In this example, the verb see is the verb of perception. The simple form of the verb move follows it.

Although HAL said "I could see your lips move," it could have said, "I could see your lips moving." The two statements are close in meaning.

Here is another example. Imagine a police detective is investigating a crime. The detective might ask people questions, like:

Detective: Did you see anything strange last night?

Witness: I saw a man run down the street.

Here the witness used the verb of perception see as well as the simple form of the verb run.

But their exchange could have been somewhat different, as we hear in this example:

Detective: Did you see anything strange last night?

Witness: I saw a man running down the street.

In this case, the –ing form of the verb comes after the verb of perception.

The first and second exchanges with the police detective are close in meaning.*

However, at other times, there is a clear difference in meaning when English speakers use the –ing form after a verb of perception, as we will find.

Difference in meaning

Sometimes English speakers use the –ing form after a verb of perception to point out that an activity is taking place when it was perceived.

Here is an example. The following statements are about the American actor and humorist Dave Chappelle.

1: I saw Dave Chappelle perform a new act last week.

2: When I walked into the comedy club, I saw Dave Chappelle performing a new act.

In both statements, see is the verb of perception. In the first statement, the verb perform appears in its simple form. In the second statement, the verb perform appears in its –ing form.

In the first sentence, I saw Dave Chappelle perform a new act last week, the speaker gives the idea that she listened to all of Chappelle's new act – from beginning to end.

In the second one, When I walked into the comedy club, I saw Dave Chappelle performing a new act, the speaker gives the idea that she entered the room when Chappelle was already performing. In other words, the speaker did not see the beginning of Chappelle's act.

Other verbs of perception - examples

In the examples we presented today, we only used the verb of perception see. Other common verbs of perception include hear, feel, watch and notice.

So one could say:

"Last night, I heard a strange sound come from the closet."

Or:

"Last night, I heard a strange sound coming from the closet."

If you wanted to point out that an action was already taking place, you could say, for example, "When I woke up, I noticed my dog snoring loudly next to me."

Closing thoughts

Today we showed you how English speakers use either simple forms or –ing forms after verbs of perception.

We showed you that sometimes the two forms have a similar meaning. At other times, they have a clear difference. The situation can give you an idea of the speaker's meaning.

While this subject might seem difficult at first, you will quickly learn it with practice.

The next time you are watching English language movies or television shows, record examples of how the speakers use verbs of perception.

You might hear them use these verbs in regular, repeated ways.

I'm John Russell.

And I'm Alice Bryant.

John Russell wrote this story for Learning English. George Grow was the editor.

*the –ing form can often convey the idea of "while." Subtle differences in meaning are beyond the scope of this article.

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perceive – v. to notice or become aware of (something)

grammar – n. the whole system and structure of a language

precaution – n. a measure taken to prevent something dangerous from happening; a safeguard

pod – n. a self-container vehicle or other device

comedy club – n. a business where humorists perform

snore – v. to breathe noisily while sleeping

practice – n. the action of repeating an exercise in order to improve one's understanding or skills