So. Beta. The second (usually second-brightest) star in a constellation. Or, denoting the second of a series of items, categories, forms of a chemical compound, etc. Or, the 2nd letter of the Greek alphabet.
Nope, not never first. Beta is second. According to Literary Rambles, A beta reader is, essentially, someone who reads your work and offers input while it is in draft form but no I say, it is less than that and yet more.
For me, my critique partners see the story first, from the very beginning where it is just words on a page, a smidgen of an idea, to the way it forms into story where we talk about the main character as if s/he exists in real time.
We worry about what is said, how it is said, what are the MC’s feelings or not, is s/he hurt or in trouble. We want s/he to get out of that trouble, to solve the mystery, to change and grow, to be better than what they were at the beginning.
So all the ins and outs of the plot, the obstacles for the main character, the needs and wants, yes all, we want it all! And then you are done. You like what you wrote. Your critique partners like what you wrote. Now what.
Second reader. Yes. someone who is not familiar with the story, the way the MC first struggled with the mystery and now struggles with emotions. You want someone who can read the story without the weeks, months, probably year or so, of attachment to the character. Yep, just like an editor or agent. Someone who is coming to the story for the first time.
I have asked one other person out side my critique group to read one of my stories. But I have recently been a beta reader for another, a friend. It was a great opportunity to see the story without introduction, like I would pick off a library or bookstore shelf or on the digital library site. I enjoyed staying with the story but making comments on the character, the nuances, the plot. Why? because most often what you see in another’s story is also happening in your story. It do make you a better writer, a better storyteller.
Yay for Second!