Secondly, developing a scan technique to give you the best chance of spotting another aircraft. However, kid yourself not, if you take the trouble to read all the research, our eyes are really not up to the job. You will get quite a different impression from this and other forum - all I can say is those who punt this are irresponsible and clearly havent read the research.
I think it is worth recalling that the research you are talking about mainly relates to the cross country type of collisions. It is also worth recalling that proper scan can still significantly reduce the risk of such collisions, while it can not bring it all the way down to zero. A third thing worth remembering is that collisions in congested areas, such as the traffic pattern, will have more to do with improper lookout than with the physiological hard limits of the eye.
To draw the right conclusions from such research, one has to understand its scope...