Imaginar vs. imaginarse

The Spanish verbs 'imaginar' and 'imaginarse' are closely related, as they both refer to the act of forming mental images or concepts that are not present to the senses. However, there are subtle differences in their usage and connotation that can be observed in different contexts.

Imaginar

'Imaginar' is a transitive verb that means 'to imagine', referring to the ability to create images or ideas in one's mind. It is often used to discuss the action of forming a concept or belief about something without necessarily having experienced it directly.
Puedes imaginar lo difícil que fue tomar esa decisión.
(Can you imagine how difficult it was to make that decision?)
Los niños pueden imaginar mundos enteros en su mente.
(Children can imagine whole worlds in their minds.)
Me cuesta imaginar la vida sin tecnología moderna.
(I find it hard to imagine life without modern technology.)

Imaginarse

'Imaginarse' is a pronominal verb that implies a more personal or subjective act of imagining. It suggests the act of picturing oneself in a situation or considering something from one's personal perspective. It often carries a sense of wonderment or disbelief.
¡Imagínate ganar la lotería! ¿Qué harías con el dinero?
(Imagine winning the lottery! What would you do with the money?)
Me imagino que estarás cansado después de tan largo viaje.
(I suppose you'll be tired after such a long trip.)
Cuando era pequeño, me imaginaba siendo un astronauta y explorando el espacio.
(When I was little, I pictured myself being an astronaut and exploring space.)

Summary

In summary, while 'imaginar' and 'imaginarse' both refer to the act of imagining, the verb 'imaginar' is often used more generally, whereas 'imaginarse' involves a more introspective process, usually personally involving the speaker and carrying an emotional or hypothetical component.