Political attack ads – fear messaging being one type – have a shakier record. A review of more than 100 studies found no dependable evidence that negative campaigning wins elections, and some evidence that it lowers positive feelings toward the candidate who sponsors it.

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Fear does its most reliable work when it attaches to a stereotype voters already carry. The 1988 presidential race provides two classic examples.

One controversial ad, produced in support of Republican George H.W. Bush, showed a mugshot of a Black man. The ad named the man, Willie Horton, and a voiceover explained that he’d committed rape and assault while on a weekend furlough from prison as part of a program run under Massachusetts Governor Michael Dukakis, the Democratic candidate. The spot linked fears about crime to race without saying so directly.

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Political scientist Tali Mendelberg’s research described in “The Race Card” shows that these implicit appeals to prejudices and fears are powerful. But they lose much of their force once someone publicly names them as racial. Implicit appeals work because they slip past most voters’ commitment to racial equality; once the racial message is pointed out, voters recognize it and many reject it rather than see themselves as endorsing prejudice.

Gender works in a similar way.

In a national experiment, Public Policy researcher Mirya Holman and colleagues found that when campaign messages triggered fears of terrorism, voters turned to their stereotypes of strong leaders as masculine. Those stereotypes hurt a female Democratic candidate, while Republican candidates of either gender were unaffected, since Republicans are already seen as tough on security.

A message communicating a threat does not need to name a candidate’s identity to disadvantage them. It simply makes voters reach for the stereotypes they already hold.