There are a couple versions of the experiment. In one, teachers are shown video of a classroom session. Before they observe, they are told that the students are either gifted, average, below average/troublesome. The teachers are asked to record their observations.
For the 'gifted' students they observed engaged students. Obviously high achievers.
For the below average/troublesome students, they tend to diagnose ADD. They pick out the troublemakers.
But the video is the same.
In another version, the teachers given pre-conceptions are actually teaching the classes. Same result. Gifted students tend to get A's and praise and the Below Average ones are graded poorly.
When I was in flight school, I saw a version of this. If someone's first flight went well then any problems on subsequent flights were seen as aberrations. If someone had a rough first flight, any successes after that were seen as aberrations. Consistent performance can get you out of the group you were placed in up front but it is difficult and rarely fully successful.
When I was in High School and College, I was often called in to join orchestras/bands. My Trumpet teacher gave me this piece of advice.
"No matter what the group is, sit at first chair"
If you sit at last chair and you really fit at a different place, they will probably move you up one chair - maybe.
If you sit at first chair, they may move you to second chair but they won't move you all the way down to the bottom.
When I am leading a new team, I keep this in mind. I know the team can be successful and I keep my expectations high. I tend to trust people with more authority than expected and try to give them permission to fail (when we can spare it). People tend to grow into the expectations you have for them. When they don't is a different story.