• She always sees things that don't exist.
  • She is always seeing things that don't exist.

In the first sentence we use verb "to see" in the present simple tense. In the second sentence, verb "to see" in the present progressive, unusual for verbs that express forms of sense perception. Are both sentences correct and interchangeable? Any subtle difference in meaning between them?

  • 1
    They're both correct, and interchangeable. I think there are subtle differences but an explanation is beyond my descriptive talents. Besides, it's time for me to get something to eat. :)
    – Mynamite
    Aug 31, 2014 at 17:44

1 Answer 1


The second sentence expresses the speaker's opinion, it suggests an annoyance or irritability at the frequency with which the woman is seeing non-existent things. The present progressive tense is used when we mention the activity, and with many senses we can use this structure.

  1. A: What are you doing?
    B: I'm tasting this stew. I think it needs a bit more salt. What do you think?

  2. A: Where's he going?
    B: He's seeing his new girlfriend. (In this instance see = meet)

  3. A: Why is he always touching his hair like that?
    B: Because he's either incredibly vain or terribly insecure. Your pick.

  4. A: Why are you smelling that meat? You only bought it yesterday.
    B: I'm sure it's gone off. Here, have a sniff.

  5. A: We're hearing all sorts of awful stories about the new neighbours.
    B: It's just idle gossip, they're perfectly fine people.

Now is the present simple tense and the progressive tense always interchangeable? No, it isn't. Compare:

  1. A: What do you do?
    B: I taste wine for a living.

  2. A: What are you looking for?
    B: My glasses. I can't see a thing without them.

  3. A: If I told you once, I told you a hundred million times. Don't touch the DVDs with your grubby fingers.
    B: Sorry...

  4. A: They say dogs can smell cancer.
    B: Really? I never knew.

  5. A: Can you hear it? There's a noise downstairs.
    B: It's nothing. Now go back to sleep.

John Lawler in an answer posted a succinct explanation on volitional and non-volitional verbs

Hearing: You listen to something on purpose, but you can hear it by accident.
Vision: You look at something on purpose, but you can see it by accident.
Verbs for the other three senses don't vary; you can smell, taste, or touch/feel on purpose or not.

Therefore with non-volitional senses such as sight and hearing, we often use can and the verb remains in the present simple, the progressive tense is more common with things we do on purpose.

Without going into greater detail, I find that Wikipedia explains well some of the differences between the present simple and continuous


Verbs of mental state, sense perception and similar (know, believe, want, think, see, hear, need, etc.) are generally used without progressive aspect, although some of them can be used in the progressive to imply an ongoing, often temporary situation (I am feeling lonely), or an activity (I am thinking about a problem). See also can


Present progressive

The present progressive or present continuous form combines present tense with progressive aspect. It thus refers to an action or event conceived of as having limited duration, taking place at the present time. It consists of a form of the simple present of be together with the present participle of the main verb.

We are cooking the dinner now. This often contrasts with the simple present, which expresses repeated or habitual action (We cook dinner every day). However sometimes the present continuous is used with always, generally to express annoyance about a habitual action:(emphasis mine)

  • You are always making a mess in the study.

Certain stative verbs do not use the progressive aspect, so the present simple is used instead in those cases

  • A rushed answer, but hope this helps!
    – Mari-Lou A
    Aug 31, 2014 at 18:13
  • Should have taken your time. After all the scolding (from several members) I got for rushing to pick a right answer a few days ago, I will certainly wait until I get four or five answers to choose from, as I had always done.
    – Centaurus
    Aug 31, 2014 at 18:18
  • Finally caught up with this post, spent a bit of time over it. Hope it's helpful.
    – Mari-Lou A
    Dec 6, 2014 at 21:34
  • Reading your previous comment, I'm a bit confused. Does this mean you know when there is a "right answer"? So is this answer "right" but you wanted to wait longer to in order to be certain, or you don't believe this answer is correct but you accepted it out of politeness?
    – Mari-Lou A
    Dec 7, 2014 at 9:05
  • Mari-LouA, To be frank with you: I've asked 132 questions so far and most of the times I didn't know the answer or I wasn't sure about it. There were a few instances, however, when I did know the answer. One would certainly ask why I posted them. The main objective of this site is to build a Q&A data-bank about the English language, so I've been led to believe. I thought those questions would make good contributions if they were answered correctly, and I usually got very good answers as in ....
    – Centaurus
    Dec 7, 2014 at 12:07

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