what is it?
Spanish perception verbs ver and oír can take a direct object followed by either an infinitive or a gerund to describe what is perceived. The choice between the two non-finite forms is not free: the infinitive presents the perceived action as a complete, bounded event, while the gerund presents it as an action caught in progress at the moment of perception. A third option, ver/oír que + finite clause, is always available as a neutral alternative but lacks the compactness and aspectual precision of the non-finite constructions.
when to use it
Ver/oír + object + infinitive — use this when the speaker witnesses the action from start to finish, or when the action is presented as a single, complete event. The focus is on the whole event, not on its duration.
Ver/oír + object + gerund — use this when the speaker catches the action already underway, perceiving only a slice of it. The gerund signals that the action was in progress at the moment of perception.
Ver/oír que + finite clause — use this when you prefer a fully conjugated verb, or when the perceived situation involves a state rather than an action. This option is aspectually neutral and is always grammatically correct, but it is more wordy.
The aspectual contrast is clearest with activities that can be observed either as a whole or mid-stream. Compare: La vi fumar (I saw her smoke — the complete act, e.g. she smoked a cigarette) vs. La vi fumando (I saw her smoking — she was in the middle of it when I looked).
formation
The structure is: conjugated ver/oír + object clitic (or full noun phrase) + infinitive/gerund. When the object is a pronoun, it must be an unstressed (clitic) pronoun attached to the perception verb, not a tonic pronoun. The clitic agrees in gender and number with the perceived person or thing.
| pattern | example | meaning |
|---|---|---|
| ver + noun + infinitive | Vi a María entrar. | I saw María go in. |
| ver + clitic + infinitive | La vi entrar. | I saw her go in. |
| ver + noun + gerund | Vi a María entrando. | I saw María going in. |
| ver + clitic + gerund | La vi entrando. | I saw her going in. |
| oír + noun + infinitive | Oí a los niños llegar. | I heard the children arrive. |
| oír + clitic + infinitive | Los oí llegar. | I heard them arrive. |
| oír + noun + gerund | Oí a los vecinos discutiendo. | I heard the neighbours arguing. |
| oír + clitic + gerund | Los oí discutiendo. | I heard them arguing. |
| ver/oír + que + clause | Vi que entraba en el banco. | I saw that she was going into the bank. |
When the object is a person and it appears as a full noun phrase (not a clitic), it takes the personal a: Vi a María entrar. Things do not take the personal a: Vi el tren llegar.
examples in context
common pitfalls
Tonic pronoun instead of clitic. When the object is a pronoun, it must be a clitic, not a stressed pronoun. «Vi a ella entrar» is ungrammatical. The correct form is la vi entrar. Tonic pronouns (él, ella, ellos…) cannot serve as the direct object of a perception verb in this construction.
Overusing que + clause. Relying exclusively on ver/oír que + clause and never producing the infinitive or gerund pattern is a common avoidance strategy. The compact constructions (la vi entrar, los oí discutiendo) are the normal, idiomatic choice in spoken and written Spanish at B2 and above.
Infinitive where the gerund is needed (and vice versa). The two forms are not interchangeable. La vi fumar reports a complete event (she smoked); la vi fumando catches her in the act. Using the infinitive when you mean to convey an ongoing activity — or the gerund when you mean a bounded event — produces a sentence that is grammatical but communicates the wrong aspect.
A quick test: if you can add de principio a fin (from start to finish) naturally, use the infinitive. If you can add en ese momento (at that moment) naturally, use the gerund.
Three sentences, graded here. Nothing is saved and no account is needed.
Cuando llegué a la parada del autobús, encontré a varios vecinos ___ bajo la lluvia sin paraguas. (esperar)
Fill in the blank with the correct form of the verb in parentheses.