Perception verbs + infinitive or gerund: la vi salir

Perception verbs at a glance

The whole page on one screen. Same verbs, two camera angles.

The infinitive is the default. Reach for the gerund only when you mean "in the middle of it" or "at it".

The infinitive: the whole action

The infinitive reports the action as one finished event:

A noun doer can go before or after the infinitive: Vi a mi hermano entrar. and Vi entrar a mi hermano. both mean I saw my brother come in.

The gerund: caught in the middle

The gerund freezes the action while it is going on. You caught it happening, without claiming you saw it start or end:

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1. 1La vi leyendo.
2. 2Lo vi cocinando.
3. 3Lo vi corriendo.
4. 4La oí hablando por teléfono.

La vi leyendo (I saw her reading), lo vi cocinando (I saw him cooking), lo vi corriendo (I saw him running), la oí hablando por teléfono (I heard her talking on the phone).

The same sentence both ways:

• Oí a Juan tocar el piano. - I heard Juan play the piano. (the whole piece, or the fact that he played)
• Oí a Juan tocando el piano. - I heard Juan playing the piano. (he was at it when I heard)

If English could add "in the middle of" or "away" (singing away), the gerund fits.

The doer: la vi, vi a Pedro

The person you see or hear is a direct object: lo, la, los, las before the conjugated verb, or a noun with the personal a:

A thing takes no a. In Spain you will also hear le vi salir for a man, which the RAE accepts; for a woman it is la vi salir. Le for her appears only when the infinitive has its own object: Le oí decir que venía. - I heard her say she was coming.