In our book the word Verism is used to describe the Romans (during the time of the Republic and the time after Nero. When Vespasian, his general, came to power) preferred style of portrait busts which differed from the youthful god like full length body portraits of the Greeks. Even though it was the techniques of the Greek sculptors the Romans took on to develop this style. I feel they advanced it by being bold enough to show the true form of the individual. Of course in Roman society this true form is highly accepted because it showed the age and experience of the subject being rendered. It was really an Oligarchy. It was older people in the Republic that had the highest social standing and who really ran things. It wasn't until the Flavian dynasty (which is also the same dynasty that took back up Verism after the Julian's did all their "role playing") that a young person had the pleasure of being placed in bust form. Though she is young and goddess like in her on right the fine lines on her neck and her contemporary hair style (popped out by corkscrew. Another skill copied from the Greeks) give away the artist intent to create an illusion of something that is real down to its smallest detail.
Though in the early Republic busts of patricians and their ancestors (imagines) were obviously very real looking. The concept behind this style and this Roman desire is about this people's need to copy and make an illusion of reality to the best of their ability. Like in the case of the patrician bust from Otricoli. The lines in this man's face are very deep, exaggerated. Like the artist wants the viewer to truly realize how old this person is. Like the experiences this man had could be measured by the lines on his face. Which of course is the impression or illusion the patron of the piece wants people to get. Especially his descendants who will be honoring him by placing his bust on display in their home.
This desire to create an illusion of reality did not just limit itself to portraits. Hadrian's country villa at Tivoli was the splash spot in which he did his best in Roman form to duplicate things such as what is called Canopus and Serapeum. The first is an Egyptian city sporting a canal to Alexandria. Where in is a temple dedicated to the god Serapis which explains the name of the second. Looking nothing like Egyptian anything. It is a pool and an artificial grotto lined with Greek statue replicas, Roman arches, lintels, and Corinthian columns. It was designed by Hadrian most likely to remind himself of this place. An illusion of something he liked.
Even the styles of Fresco wall paintings are designed to create an illusion of space, marble, and distance beyond the walls themselves. So, I believe it is this obsession with creating the illusion of something that drove the Romans to produce such super realistic art. Even in their Propaganda related art which involved a kind of role playing started by the Julian Caesars, which is a whole other subject, created an illusion though not like reality did make the patron's desired impression present. That those in power were god like and deserved honor because their "divine" feats had provided wealth for the empire. The old folks of the Republic desired to be rendered as old because this showed standing. Augustus desired to be shown as young and god like because times had changed considering the young age he came to power. So, now the style was the eternal illusion of youth.
This is getting long so I better close. The Romans were a confident race who somewhat had their own culture but mostly chose to copy the culture of everyone they conquered. So, in a way all their art was the illusion not only of reality as they preferred it but of all the creative innovations of the people they assimilated.
(And just think how realistic these old fogeys would have looked to us with their original paint. )