Kennedy thought for a moment "The encephalographic part of the machine measures the exact pulsations in the individual corresponding to the various emotional reactions. It takes me about four hours to determine those with the necessary precision; then I have to make statistical analyses of the data, to winnow out random variations. Thereafter I put the subject in a state of light hypnosis--that's only to increase suggestibility, and make the process faster. As I pronounce the words and names I'm interested in, the machine feeds back the impulses corresponding to the emotions I want: a sharply-focused beam on the brain center concerned. "For instance, suppose you were an alcoholic and I wanted to cure you. I'd put you in hypnosis and stand there whispering 'wine, whisky, beer, gin,' and so on; meanwhile, the machine would be feeding the impulses corresponding to your reactions of hate, fear, and disgust into your brain. You'd come out unchanged, except that your appetite for alcohol would be gone; you could, in fact, come out hating the stuff so much that you'd join the Prohibition Party--though, in actual practice, it would probably be enough just to give you a mild aversion." "Mmmm--I see. Maybe." Fraser scowled. "And the--subject--doesn't remember what you've done?" "Oh, no. It all takes place on the lower subconscious levels. A new set of conditioned neural pathways is opened, you see, and old ones are closed off. The brain does that by itself, through its normal symbolizing mechanism. All that happens is that the given symbol--such as liquor--becomes reflectively associated with the given emotional state, such as dislike." Kennedy leaned forward with an air of urgency. "The end result is in no way different from ordinary means of persuasion. Propaganda does the same thing by sheer repetition. If you're courting a girl, you try to identify yourself in her mind with the things she desires, by appropriate behavior.... I'm sorry; I shouldn't have used that example.... The machine is only a direct, fast way of doing this, producing a more stable result." "It's still--tampering," said Fraser. "How do you know you're not creating side-effects, doing irreparable long-range damage?" "Oh, for Lord's sake!" exploded Kennedy. "Take your mind off that shelf, will you? I've told you how delicate the whole thing is. A few microwatts of power more or less, a frequency-shift of less than one percent, and it doesn't work at all. There's no effect whatsoever." He cooled off fast, adding reflectively: "On the given subject, that is. It might work on someone else. These pulsations are a highly individual matter; I have to calibrate every case separately." There was a long period of silence. Then Fraser strained forward and said in an ugly voice: