I'm pretty sure my area of concious visual focus is around 35mm. With the T3 and 18-55, using the lens zoomed out all the way is definitely too wide. To match the size of objects in the viewfinder with my other eye I have to zoom it in all the way, it would probably have to go to 57mm to be a perfect fit. I'm not sure how the viewfinder is adjusting things though. 85mm on the 5D2 is definitely more zoomed in than what I see, so 57mm is probably correct.
Now if you want to try something trippy, get a zoom lens to match your vision, so that keeping both eyes open with the camera in front of one looks normal, just with that eye cropped, then move the camera out of focus. I can actually get my brain to clearly focus on one object in my unobstructed eye, while seeing everything else out of focus through the camera. For the first few seconds before getting nauseous it was a really neat thing to look at, kind of a super bokeh effect.