Percibían
Percibían is a Spanish verb, specifically the imperfect indicative third-person plural form of the verb percibir. Percibir generally translates to "to perceive," "to sense," "to notice," or "to detect." The imperfect tense in Spanish is used to describe ongoing actions, habitual actions, or states of being in the past. Therefore, "percibían" describes an action of perceiving, sensing, noticing, or detecting that was happening repeatedly, continuously, or as a background state in the past, performed by multiple people or entities (they).
For example, one might say "Los antiguos griegos percibían la luz de las estrellas de manera diferente"