Allowing experience, shikantaza, headless experiments and the Big Mind/Heart process are all flavors of a similar shift.
And they can all fall a little differently on several dimensions, often depending on intention, experience and more.
The shift into allowing experience, into headlessness, Big Mind, realized selflessness, can be more or less partial, more or less clear.
It can be done with an emphasis on Big Mind, seeing all as awareness itself.
It can be done with an emphasis on the heart, on kindness, Big Heart.
It can be done with an emphasis on the felt sense of the shift, how it feels in the body.
It can be done with an emphasis on our human self, on who we are.
It can be done with an emphasis on what is here now, as it is, or on what is here now unfolding over time, revealing a process and a journey within content of experience.
And it can be done as a combination of any of these, simultaneously or shifting attention over time.
When it is a partial shift, there is still some identification with content of experience, specifically with the story of a separate I, the sensations this is anchored on (usually in the head area), and the stories fleshing out this I. Intention and sincere exploration can bring about a partial shift, which invites in a more full and clear shift.
When there is an emphasis on Big Mind we explore how all content of awareness is awareness itself, how it is ephemeral, insubstantial, not real beyond appearance.
An emphasis on Big Heart invites in kindness towards ourselves and others, and healing for our won human self.
An emphasis on the felt sense of the shift makes it more real for us, it helps more of us reorganize within this new context.
A shift into Big Mind, with an emphasis on our human self, helps us see all of it as awareness itself, and the mechanisms of samsara. It helps us see our human self as content of awareness just like any other content of awareness, inherently free of a separate I. A shift into Big Heart, with an emphasis on our human self, invites in a healing of our human self.
And there can be an emphasis on whatever is here now, as it is. Or an emphasis on the unfolding over time within content of experience. A journeying which can give us insights into processes and dynamics of our human self, and invite in healing.