Incognito by David Eagleman Page B

sounds, all these findings passed the statistical thresholds for significance. The effects are not large, but they’re verifiable. We are influenced by drives to which we have little access, and which we never would have believed had not the statistics laid them bare.
TICKLING THE BRAIN BELOW THE SURFACE OF AWARENESS
     
    Your brain can be subtly manipulated in ways that change your future behavior. Imagine I ask you to read some pages of text. Later, I ask you to fill in the blanks of some partial terms, such as
chi___ se___
. You’re more likely to choose terms that you’ve recently seen—say,
chicken sexer
rather than
china set
—whether or not you have anyexplicitmemory of having recently seen those words. 15 Similarly, if I ask you to fill in the blanks in some word, such as
s_bl_m_na_
, you are better able to do so if you’ve previously seen the word on a list, whether or not you remember having seen it. 16 Some part of your brain has been touched and changed by the words on the list. This effect is calledpriming: your brain has been primed like a pump. 17
    Priming underscores the point thatimplicit memory systems are fundamentally separate from explicit memory systems: even when the second one has lost the data, the former one has a lock on it. The separability between the systems is again illustrated by patients with anterograde amnesia resulting from brain damage. Severely amnesic patients can be primed to fill in partial words even though they have no conscious recollection of having been presented with any text in the first place. 18
    Beyond a temporary tickling of the brain, the effects of previous exposure can be long lasting. If you have seen a picture of someone’s face before, you will judge them to be more attractive upon a later viewing. This is true even when you have no recollection of ever having seen them previously. 19 This is knownas the
mere exposure effect
, and it illustrates the worrisome fact that your implicit memory influences your interpretation of the world—which things you like, don’t like, and so on. It will come as no surprise to you that the mere exposure effect is part of the magic behind product branding, celebrity building, and political campaigning: with repeated exposure to a product or face, you come to prefer it more. The mere exposure effect is why people in the public spotlight are not always as disturbed as one might expect by negative press. As famous personalities often quip, “The only bad publicity is no publicity,” or “I don’t care what the newspapers say about me as long as they spell my name right.” 20
    Another real-world manifestation of implicit memory is known as the
illusion-of-truth effect
: you are more likely to believe that a statement is true if you have heard it before—whether or not it is actually true. In one study, subjects rated the validity of plausible sentences every two weeks. Without letting on, the experimenters snuck in some repeat sentences (both true and false ones) across the testing sessions. And they found a clear result: if subjects had heard a sentence in previous weeks, they were more likely to now rate it as true, even if they swore they had never heard it before. 21 This is the case even when the experimenter
tells
the subjects that the sentences they are about to hear are false: despite this, mere exposure to an idea is enough to boost its believability upon later contact. 22 The illusion-of-truth effect highlights the potential danger for people who are repeatedly exposed to the same religious edicts or political slogans.
    A simple pairing of concepts can be enough to induce an unconscious association and, eventually, the sense that there is something familiar and true about the pairing. This is the basis of every ad we’ve ever seen that pairs a product with attractive, cheery, and sexually charged people. And it’s also the basis of a move made byGeorge W. Bush’s advertising team during his 2000 campaign againstAl