Margaret shrugged. ‘What’s to know? It’s just a bunch of wires and sensors that read heart-rate, breathing, perspiration. The operator is the lie detector, not the machine. It’s all psychology. Smoke and mirrors.’
Hart laughed infectiously. ‘You’re right, of course, Margaret. Which is why experience counts for so much.’
‘Then how come you manage to get it wrong so often?’
‘Margaret…’ Li said, a hint of warning in his voice.
But Hart was unruffled. ‘Relax, Li Yan, I’m enjoying this. It’s good to do battle with someone who can make a good argument.’ He turned back to Margaret. ‘Actually, we have a pretty high success rate. Ninety per cent or higher.’
But Margaret was unimpressed. ‘Not according to the OTA. You know what that is?’
‘Sure. The Office of Technology Assessment. It’s an arm of the US federal government that analyses and evaluates current technology.’
‘Whose evaluation of the success rate of the polygraph is as low as fifty per cent. Hell, I can guess and be right half the time.’
Lyang was grinning. ‘Still enjoying the argument, Bill?’
But Margaret wasn’t finished. ‘I read somewhere that between one and four million private citizens in the US submit to a polygraph every year. Even assuming you did have a ninety per cent success rate, that’s a heck of a lot of people to be wrong about. People who might lose or fail to gain employment, people stigmatised as liars because of inaccurate polygraph tests. It’s not science, Bill, it’s voodoo.’
Hart’s grin never faltered as he eyed Margaret with something approaching admiration. ‘Jesus, Margaret, they were right about you. I’d love to get you in the chair and wire you up. Pin you down on my territory.’
‘Okay,’ Margaret said, to everyone’s surprise.
‘What, you mean you’d let me give you a polygraph test?’
‘If you let me give you an autopsy.’ The others roared with laughter. And Margaret broke into a smile for the first time. ‘I reckon I’d find out a lot more about you in an hour and a half than you’d ever find out about me.’
Hart nodded, still smiling, acknowledging defeat. ‘Okay,’ he said. ‘I give in. Let’s eat.’
And the waitresses brought the mushrooms to the table and started cooking them in the stock with the chicken. Lyang showed Margaret how to mix up her own dip from three dishes of sesame paste, chilli and garlic, and dip the cooked pieces of mushroom in the mix before eating. Margaret was surprised at just how delicious the mushrooms were, each with its own distinctive flavour and texture. A waitress broke up the chicken in the pot and served portions of it into each of their individual bowls. It melted in the mouth.
‘Actually,’ Hart said, washing down mushroom with beer, ‘I’m not in favour of using the polygraph on employees or job applicants. I regard it only as a useful tool in criminal interrogation. It is at its most effective when the suspect believes the machine will catch him in a lie. You’d be amazed at how often they just confess.’ He spooned some of the stock into his bowl and drank it like soup. ‘You know, the Chinese invented a pretty good method of lie detection about three thousand years ago.’
Li looked up surprised. ‘We did?’
‘Sure we did,’ Lyang said. ‘Works on the principle that if you are telling a lie you produce less saliva. So the ancient Chinese gave the suspect a mouthful of rice to chew, then told him to spit it out. If he was afraid of the test, because he was lying, he would suffer from dry mouth and the rice would stick to his tongue and the roof of his mouth. An innocent person, on the other hand, would be able to spit it out clean.’
Hart said, ‘But the Indians had an even better one. They would put lampblack on the tail of a donkey and lead it into a dark room. Suspects were ordered to go into the room and pull the donkey’s tail. They were told that it was a magic donkey and would be able to tell if the suspect was being truthful or not. When the suspects came out of the room their hands were examined. If they didn’t have any lampblack on them they hadn’t pulled the donkey’s tail. Why? Obviously because they were scared of being found out. Guilty as charged.’
‘Almost as scientific as the polygraph,’ Margaret said.
‘Well, if it’s science that impresses you,’ Lyang said, ‘it’s a pity you won’t be at the MERMER demonstration this afternoon.’
Margaret looked at Li. ‘And why am I not invited?’
Li said, ‘Because it’s a demonstration for top Ministry of Public Security people, Margaret. The deputy minister himself is going to be there.’
‘We’re trying to secure funding for further research,’ Hart explained.
‘Don’t worry, I’m not invited either,’ Lyang said. ‘Husbands don’t like their wives seeing them caught in a lie.’
Hart held his hands up. ‘I am taking no part in this demonstration. I just set it up for Lynn.’
‘Who’s Lynn?’ Li asked.
‘Professor Lynn Pan. She’s an American Chinese. She was a pupil of the system’s inventor, Doctor Lawrence Farwell, back in the States. She came to live and work in China last year, sponsored by the Chinese Academy to develop a Chinese version of MERMER.’
‘What exactly is Mermer?’ Margaret asked, intrigued.
‘It’s an acronym,’ Lyang said. ‘It stands for Memory and Encoding Related Multifaceted Electroencephalographic Responses.’
‘Sorry I asked,’ Margaret said. ‘What does it mean?’
Hart said, ‘Electroencephalography is a non-invasive means of measuring electrical brain activity.’
Lyang waved her hand dismissively. She turned to Margaret. ‘He’s a scientist, he doesn’t know anything about language. In layman’s terms, they put sensors on your scalp and use a computer to measure your brain’s electrical responses to certain stimuli. Might be something as simple as a photograph of your child. You recognise it, so your brain makes an entirely involuntary electrical response. Proof that you know this child. They show you a picture of someone else’s child, you have no response. You don’t know the kid.’
Hart said, ‘It can be used to discover guilty knowledge in the brain of a criminal. They’ve done extensive testing in the States, using FBI and CIA personnel.’ He smiled. ‘Since you’re so interested in percentages, Margaret, you’ll be pleased to know it has proved one hundred per cent successful in all tests to date.’
‘Sounds like it could put you guys out of business.’
‘Oh, I doubt it,’ Hart said. ‘MERMER has very specific and narrow applications. It requires a lot of expensive equipment and meticulous preparation.’ He glanced at his watch. ‘Speaking of which, we don’t want to be late.’ He signalled the waitress for the check and a gaggle of girls rushed to get their jackets from the stand.
As they rose from the table, Lyang said, ‘Are you busy this afternoon, Margaret?’
Margaret laughed. ‘Lyang, these days I’m never busy.’
Lyang said, ‘I’m going for a foot massage later. Why don’t you join me?’
‘A foot massage?’ Margaret was incredulous. She had seen the signs for foot massage springing up all over the city. It was the latest fashion. But it seemed a little decadent.
‘It’s the most wonderful way of relaxing I know,’ Lyang said.
‘It’s not so easy to relax with an eleven-month-old baby demanding your attention twenty-four hours a day.’
‘That’s what’s so good about the place I use,’ Lyang said. ‘They have a crèche. You can forget baby for an hour and a half.’ She smiled. ‘Go on, treat yourself.’
‘On you go,’ Li said. ‘And when you learn how it’s done you can practise on me.’
Margaret gave him a look.
As a waitress handed Li his coat, Qian’s book slipped from the pocket and fell to the floor.
Lyang stooped to pick it up and raised an eyebrow as she read the title. ‘The Murders of Jack the Ripper.’
Hart laughed. ‘What’s this? Becoming a student of unsolved murders, Li?’
Li smiled reluctantly. ‘I hope not,’ he said.