And that’s one of the challenges of assessing posture.
The solution to shift the benchmark of “normal” to their “perception of best normal”. The simple cueing phrase of “Show me your BestPosture” changes their reaction and forces them to assess “What IS normal?”. For the 30% or so of people who still stiffen unnaturally, simply saying “Relax- don’t stiffen, just stand up with your BestPosture” usually gives a baseline to benchmark their posture. Then, whether you are looking at their Annual Posture Picture or a post-treatment comparison, you are factoring in their self awareness and comparing Newtonian apples to apples.