While non-judging is the attitude we take to our habit of discriminating based on how we value things, beginner's mind is how we deal with the habit of creating expectations based on our past experience and how we then let our thinking and beliefs about what we 'know' prevent us from seeing things as they really are.
In my qigong (similar to tai chi) class for example, beginner's mind is the attitude that my new students have in the first few weeks and months of coming to my evening class. In this initial stage they rarely have enough knowledge to question what they are learning and they will usually accept what I say and just practice the exercise. Students tend to begin to ask meaningful questions once they have a basic understanding of the principles of the skill and have practiced the movement frequently enough so as to be able to reflect of what they are doing. While this is a critical part of reflective practice, this accumulated knowledge can also be a trap. Once we think we know something, it can be easy to see things through this frame of reference, rather than seeing things as they actually are.
A good word for this habitually formed expectation based on our past experience is 'preconception’ the definition of which is 'an assumption about something not yet experienced, often a prejudice'. Another, slightly stronger word for this is 'stereotype', which is defined as 'a widely held but fixed and oversimplified image or idea of a particular type of person or thing'. When we are acting from these preconceived ideas then we risk not being centred upon the person in front of us. In contrast, if we are aware of our preconceptions then we can either let them go and concentrate on what is happening now or alternatively we can reflect on them and consciously decide if they are useful.
I have many conversations at Woolley Wood School and other services about preconceptions and how these fixed ideas can affect our sensitivity as practitioners. During a video mentoring session, I remember watching a video of a teacher doing Rapport-Based Communication who seemed to be trying to instigate an interaction every so often by tapping her leg. Her attempt at initiation was rejected each time and, since she did not appear to be initiating based on a cue from her partner, I asked her why she was doing this. The teacher's astute reflection was that she had had a really good interaction with another child and that she was instinctively trying to recreate this level of interaction with her new partner. We talked about how it is easy to let these past experiences affect how we see what is happening now and that this can mean that we fail to see the extraordinary things that are right in front of us. In this case, the teacher's the success that she wanted to see had blinded her to the success that she was already a part of... that the teacher and the child were happily sharing space, enjoying each others company and engaging in what was, for the child concerned, a rare moment of cooperative play.
Reference
Kabat-Zinn, Jon. 2013. Full Catastrophe Living: Using the Wisdom of Your Body and Mind to Face Stress, Pain, and Illness. New York: Bantam Books.