This question came up in the Online 10-day Retreat Nov 3, 2020, guided by Delson Armstrong. Day 3 was part of a daily 30 -minute discussion on the suttas, the Dhamma talk and reflections.
Slightly edited to improve readability
Manasikara literally means; taking to heart. Unifying, in that sense, your mind with that object. Or with the understanding of that object. It’s taking to heart what you’re seeing.
The root of the word yoniso is yoni, which means the source, the origin point. There are a lot of different ways to look at this word. Like a lot of words in Pali or Sanskrit, it’s polysemous, which means that one word can have multiple shades of meanings and variations.
If you look at the text of the book you guys are using as part of this retreat, it was chosen to be translated as: attention rooted in reality.
Yoniso manasikara really is right attention. You are really paying attention. And what you are paying attention to is the things that arise in the reality of the situation. So, it is along with this unified attention, unified mind set.
Ayoniso manasikara means unwise perception, or inattention, or unwise attention. Meaning, you are not paying proper attention to your object. When that happens, that gives rise to hindrances, gives rise to distractions. Whereas correct attention is not focused, it’s not full-fledged focus but it is more about understanding how things are arising in the present moment.
Another variation of this meaning is also when the Buddha, or any of the monks use yoniso manasikara, they use it in a way to find the cause of something. For example, in the line of Dependent Origination, the Buddha will say: Birth having come to be, what is the origin of Birth, what is the cause of Birth. And then he says: Being come to be, and so on. That is another variation on yoniso manasikara.
But for the purpose of practice and the purpose of the meditation, whether it is in sitting practice or in your daily life, you have to pay attention, meaning you have to understand, how reality is arising as it arises. How it’s unfolding and, accordingly, make changes to your meditation practice, in the way of using the 6R’s, or whatever it might be.
It is actually through this yoniso manasikara that you are aware of, to link back to the previous question, what certain jhana factors are present. Or aware of what certain mind objects are present, what distractions, or what insights might arise. Or anything else like that.