Hi Jon, When you asked about "Up to 50% of "vision" is modified by traffic going in the other direction - back to the visual cortex" you wrote: "traffic going in the other direction" is directed by "Attention" Not by attention in the sense of conscious focus. It's all done unconsciously and then we become conscious of it. For example the act of facial recognition is a complex pathway involving the temporal lobe, pre-frontal cortex and limbic system. Yet all this action and interaction, checking and rechecking gives you the feeling of recognition just before you are consciously aware of "what" is recognised. You will "see" the "what" that is recognised differently depending on the state it evokes (e.g.fear and pleasure) - it will literally change the visual submodalities. The visual cortex can also fill in things that are "not there". A visual scotoma is a filling defect (like the blind spot), yet depending on its size the visual cortex fills in the information "as-if it were seeing what is there, like a background wallpaper. When we are focusing on one thing there is evidence that we "fill-in" the background. Of course spontaneous hallucinations and illusions are more graphic examples of the same phenomena - up to 100% seeing what's not there. You also wrote: ""traffic going in the other direction" is to a large extent (depending on skills of the user) under our control." I think this is partly true only. Some aspects of vision - what is called the "how" pathway in blindsight together with other "non-conscious" visual pathways via the brainstem - never reach the light of day. Curiously they can give an emotional recognition but not a visual one! However the higher cortical functions can be modified by state - e.g. peripheral vision (parasympathetic arousal) versus foveal vision (sympathetic arousal), meditation, trance, etc, etc - and it is these higher functions that I believe John and Carmen are meaning when they speak about suspension of f2 filters (Perhaps J and C could confirm, and also comment (or not!) on whether a pure FA is obtainable - and how). Regards,  Lewis.