When people make sense of the world, they don't only pay attention to what's actually happening. Their mind also takes them to counterfactual worlds of what could have happened. In this talk, I will illustrate how we can use eye-tracking to uncover the human mind's forays into the imaginary. I will show that when people make causal judgments about physical interactions, they don't just look at what actually happens. They mentally simulate what would have happened in relevant counterfactual situations to assess whether the cause made a difference. And when people try to figure out what happened in the past, they mentally simulate the different scenarios that could have led to the outcome. Together these studies illustrate how attention is not only driven by what's out there in the world, but also by what's hidden inside the mind.