From its inception in the mid-1950's, the cognitive revolution was guided by a single metaphor: the mind is like a computer. We are a set of software programs running on 3 pounds of neural hardware. (Cognitive psychologists were interested in the software.) While the computer metaphor helped stimulate some crucial scientific breakthroughs - it led, for instance, to the birth of artificial intelligence and to insightful models of visual processing, from people like David Marr - it was also misleading, at least in one crucial respect. Computers don't have feelings. Because our emotions weren't reducible to bits of information or logical structures, cognitive psychologists diminished their importance.
Now we know that the mind is an emotional machine. Our moods aren't simply an irrational distraction, a mental hiccup that messes up the programming code. As this latest study demonstrates, what you're feeling profoundly influences what you see. Such data builds on lots of other work showing that our affective state seems to directly modulate the nature of attention, both external and internal, and thus plays a big role in regulating thinks like decision-making and creativity. (In short, positive moods widen the spotlight, while negative, anxious moods increase the focus.) From the perspective of the brain, it's emotions all the way down.
(From The Frontal Cortex.)