I agree with what you've said re: heat pits, striking, etc. I was speaking (in the sense that rg has continued) about what constitutes 'sight'. Semantics, perhaps, but I would say that the term 'sight' is derived from 'eyesight', which implies the use of 'eyes'. Since these heat pits don't replace the eyes, but are in addition to them, I would consider this to be a wholly separate sense, and hence I refer to it as 'heat sensing' for lack of a better, monosyllabic term. Now, one could argue that 'sight' is the perception of light via whatever organs can do it, and since what is being sensed is infrared wavelengths of light, heat pits could be said to 'see'. I just don't use this definition.
"think about it man, if vipers do make a mental image of prey, its only a blob of heat, think about how heat travels, and its impossible to imagine heat being able to make a picture, even if the heat pits were connected directly to the brain.
sight touches everything, and heat has to travel on to/in/up there heat pits. It probably not much different to feeling somthing warm by ur lip, except much much more sensitive "
Now this is absolutely wrong. Heat pits do NOT depend upon radiation or convection to transfer heat from a heat source. They sense the infrared light given off by the object. It is like the thermal imaging cameras you see on TV.
Not sure on the performance of constrictor heat sensors, but viperid sensors are astonishingly accurate and quick. In fact, it was only a few years ago that we could even measure how accurate they are. I'm pulling this from memory, but I believe it was a species of rattlesnake that could determine a difference of 0.003 degrees Celsius, within 0.01 seconds. Now that's pretty sensitive! 'Heat sense' is the main targetting sense for viperids to strike their prey.