Lyang flashed the arrow around the screen with frightening speed, opening and closing folders. There were three graph files in each of the Graph folders, but instead of being empty, the Pics folders now contained jpeg images of all the photographs the testees had been shown during the MERMER demonstration.
Li said, ‘Bill told me that one of Pan’s students thought she still had those on disk at home.’
‘Looks like she came up with the goods, then,’ Lyang said. ‘We can look at all of these.’
Margaret leaned in closer to the screen. ‘But you won’t be able to see the graphs, will you? Not without the software.’
Lyang’s arrow shot across the screen and double-clicked on the MRM icon. ‘Looks like Bill thought of everything,’ she said. The computer whirred, and images flashed across the screen as the MERMER software loaded up. ‘He’d have known he’d need a copy of this to work with the graphs at home.’
‘What’s this?’ Li stabbed a finger at the thirteenth folder. It was labelled, Report.
Lyang opened it up to reveal a word-processing document. She double-clicked to open it. A document unfolded on the screen. It was headed Preliminary Findings, MERMER Demo — Bill Hart. ‘Seems he already started to write up what he found,’ Lyang said, and her voice cracked on found. She put her hand to her mouth to hold back her emotion, and bit hard on her finger. ‘Typical Bill,’ she said.
Li pulled his chair closer to read the document which Hart had written.
A careful comparison of the first of the three graphs in each folder with the known sequence of photographs shown to each subject has enabled us to identify which of them was briefed on the murder for the purposes of the demonstration. MERMER responses to the ‘probe’ photographs, all of which related to the murder, were easily identified on the graphs. As a result, we were able to pinpoint A, B and C as the ‘murderers’, thereby eliminating them from our attempts to identify subject D, whom Professor Pan had labelled a ‘Liar’.
Li sat stunned. He knew who had been briefed on the murder, because he was one of them. And the Procurator General and Commissioner Zhu were the others. Which meant that Zhu was not the liar, and therefore almost certainly not the killer.
‘That blows a bit of a hole in your theory about the Commissioner,’ Margaret said helpfully. ‘Who’s left?’
Li said, ‘His deputy, Cao Xu, the Deputy Minister, and Yan Bo, the Director General of the Political Department.’ And he remembered Yan Bo scribbling in red ink on his notepad.
‘Jesus,’ Margaret said. ‘So now we’re climbing even higher up the ladder.’
Li turned back to the screen, agitated now. There was more.
Identifying why Professor Pan labelled subject D a ‘Liar’ has proven more difficult. Apart from a continuity of response to the ‘probe’ pictures — that is to say, none of them showed a MERMER response — the graphs relating to the ‘target’ and ‘irrelevant’ pictures appear to be anomalous.
And that was as much as Hart had written.
‘Is that it?’ Li said.
Lyang shook her head, scrolling up and down the page. ‘There’s nothing else. If he knew more than that he’s taken it with him.’
‘But what does he mean, anomalous?’ Li said.
‘Hang on,’ Margaret interrupted. ‘You two are way ahead of me here. Would someone like to explain what targets and probes and irrelevants are? It’s like another language.’
Lyang turned towards her. ‘Three of the six subjects were briefed on a murder, for the purposes of the demo. When it came to the test all six were shown nine photographs relating to that murder — things that only the ones who’d been briefed would recognise. They’re called probes. They were also shown nine photographs of things that were known to them — their apartment, their dog, their car. And these are called targets. The idea being that the brain’s response to these things that are known to them will be the same as the response to the probe photographs. In the case of the ones who were briefed, that is. And not, in the case of the other three.’
Margaret was nodding. ‘Okay, and let me guess. The irrelevants are photographs that don’t mean anything to any of them, so they have negative responses to compare to the positive ones.’
‘You got it,’ Lyang said. ‘And they get to see thirty-six irrelevants.’
‘So what did Bill mean by anomalous?’ Li asked again.
Lyang rubbed her tired and swollen eyes. ‘I don’t know. It may be that they were getting a MERMER response from some of the irrelevants.’
‘You mean recognising pictures of things they weren’t expected to?’ Margaret said.
‘Exactly,’ Lyang said. ‘It can happen. Sometimes an irrelevant is accidentally known to them. Usually they are given a list of things in advance, so that if they might be shown something they recognise it can be changed before the actual test. That wouldn’t have been done for the demo.’
Li was shaking his head, baffled. ‘So how could Lynn Pan possibly tell from any of these responses that somebody was lying? I mean, lying about what? Lying how? All they were doing was looking at pictures.’
‘Wait a minute, wait a minute,’ Margaret said suddenly. She looked at Li. ‘You remember Mei Yuan’s riddle?’ He looked at her blankly. ‘The one about the two deaf mutes in the paddy field.’
Li blinked in surprise. ‘So she tried that one out on you after all.’
But Margaret wasn’t listening. Her mind was racing off on lateral plains. ‘Each of them thought he was left in that field on his own,’ she said. ‘And that the other one had sneaked off with the food or the drink to keep it for themselves.’
‘You’ve lost me,’ Lyang said, looking from one to the other through a haze of fatigue.
So Margaret told her the riddle, but didn’t wait for her to work it out. ‘It was dark,’ she said. ‘That’s why they couldn’t see one another. They were both there, and neither of them was lying about it. They were both telling the truth, but they just didn’t know it.’
‘You’ve lost me now, too,’ Li said.
Margaret was searching for a way to unfuzz her mind, to express herself clearly. She waved a hand at the computer. ‘This MERMER thing. It can’t tell if you’re lying, right? Your brain sees something it recognises, it makes an involuntary response. You record it right there on the graph, and it’s plain for everyone to see. You see something you don’t recognise, you have no response. That’s also on the graph. So it’s got nothing to do with lying. But it’s got everything to do with telling the truth.’
They were both looking at her, concentrating hard, waiting, still not getting it.
‘Don’t you see? You can’t help but tell the truth, because you have no control over how your brain responds. Lynn Pan must have known there were anomalies in the irrelevants. But that’s neither here nor there. If you have a MERMER response to something you’re not supposed to, well that’s just a measure of the imperfect conditions in which the test was being conducted. But if you don’t have a MERMER response to something you should have, then that’s weird. That’s really off the wall. That doesn’t make any sense at all.’
Light began to dawn in Li’s eyes. ‘It’s one of the targets,’ Li said. ‘He didn’t recognise something he should have.’ Then he frowned. ‘What the hell could that be?’