I definitely do not think that snakes alone were the cause for the honing of vision in old world primates, but the fact that they could be a major contributor doesn't seem far fetched. I don't know much about venomous snakes but I think they're usually pretty colorful which would explain the development of seeing in color. For those species of venomous snakes which were not brightely colored I would imagine that acute vision would be really important to spot them out in their natural environments while foraging for food.

interesting how rhesus monkeys were able to be easily conditioned to be fearful towards a spliced video tape showing other monkeys being scared of a snake.....but not to flowers.
So I guess the rhesus monkeys were either instinctually responding with fear to the toy snakes or knew that the flower was not a threat. I know that would be a rational thought coming from a monkey, but you never know for sure what it is they're exactly thinking.

Both articles were none the less very interesting. The fact that animals with no venomous snakes in the area experienced less evolutionary growth in their visual systems is also very interesting.