Truth is, negative advertising is not some evil or nefarious practice. In fact, when I contributed to the Obama campaign in 2008, I wrote on the check: “For Negative Ads Only.” I love negative ads. When I see a positive ad, even one from a candidate I support, my reaction often ranges from bored to annoyed. But show me a negative ad—even one against a candidate I support—and my blood starts to race. What can I say? I’d much rather eat picante sauce than chocolate.

Some of our predilection for the negative may be due to evolutionary biology. Drew Westen, a psychologist and neuroscientist at Emory University, notes that “when we were evolving, failing to pick up on negative cues could lead us to fail to escape or fight a predator.” Positive cues, on the other hand, didn’t “save us from danger in the same way.” Then there’s the fact that there are fewer forms of positive cues: “friendship, loyalty, romantic desire, and emotional attachment to kids, parents, and partners.” Negative cues, by contrast, take a wide variety of forms: “distrust, contempt, anger, hate, fear, anxiety, sadness, pity. There are just many more ways to have negative feelings toward someone.”