[P]sychometric analyses of 247 samples reveal that these ability differences are minute. In terms of percentage lie detection, real standard deviations in judge ability are less 1%. In accuracy, judges range no more widely than would be expected by chance, and the most accurate judges are no more accurate than a simple chance mechanism would produce.
As judges of deception, people differ more in credulity than ability: some are more inclined than others to regard statements as truthful. . . .
Some people are highly credible (whether lying or truth-telling), and others are not credible. The outcome of a deception judgment depends more on the target’s credibility than any other individual difference. In terms of percentage truth judgments received, real standard deviations from target to target are 11.58%.
Hat Tip to Science News.