1. The study used participants who were of the ages 7 to 11, ages far lower than what is required by DSM and PCL-R standards for a diagnosis of antisocial personality disorder and psychopathy, respectively. And because the study was conducted only a few months ago, it's impossible to determine if these little jackasses are even psychopaths at all, at least until they hit 18. As we all know, the reason for these age requirements is that a child's personality is still very malleable. It's entirely possible they'll see that ultra-violence isn't all that fun any more, and maybe they'll become productive members of society.

2. The study either didn't indicate their method of differentiating between primary and secondary psychopathy in the participants, or they didn't do it at all, which I highly suspect to be the case. As we all know, secondary psychopathy is the result of a combination of other mental disorders, mostly brought on by a poor childhood. Secondary psychopaths are high in anxiety, whereas primary psychopaths are not. Furthermore, they perceive and experience emotion differently. In fact, one study found... "Results generally indicated that primary psychopathic-traits were positively correlated with accuracy of perception of fearful faces and [positive emotion], and negatively associated with [negative emotion], while secondary psychopathic-traits were not related to emotional recognition or [positive emotion], but positively associated with [negative emotion]." [Del Gaizo, Ariel L. Primary and Secondary Psychopathic-traits and their relationship to perception and experience of emotion. Personality and Individual Differences, Vol 45(3).

3. The researchers used the APSD to determine psychopathic traits in these wee tots, a scale which is largely based on Hare's PCL-R. This is good and all (considering the PCL-R is the most reliable measurement of psychopathic traits on the market at this time), but the PCL-R does not measure anxiety traits in individuals, as noted by the fact that secondary psychopaths oft score very high on the PCL-R despite their high anxiety.

4. Their sample study was essentially comprised of a bunch of insufferable, little jackasses. What did they expect to find? Considering their sample, I'd put money on the notion that most of those kids were not primaries, but secondary psychopaths in the making, as secondary psychopaths are known for their erratic, violent, antisocial behaviour and emotional disturbance.