[Gnosital]

Victus wrote

Where reactive aggression is linked to poor behavioral inhibition (seen in psychopaths and other disorders), instrumental aggression, I would posit, is a function of poor socialization. One of the unique factors seen in psychopathy is a limited emotional affect (Factor 1 PCL-R). This could explain why instrumental aggression is more prevalent in psychopaths.

Why would you link psychopathy to poor socialization, when there is a fair bit of evidence for altered neurophysiology? I'm not really familiar with the literature on psychopathy outside of what I've read on neurophysiology (sorry, I don't have the refs), but I recall seeing papers on hypoactivity of cortical (and maybe limbic?) structures, and something about smaller orbitofrontal regions. Besides that, I recall there is a component of the diagnostic criteria in DSM-IV that includes manipulative qualities of the psychopath, and as I understand it, psychopaths can be incredibly charming and highly socially skilled when it suits them to be. Anyway, I'm not sure that it's necessary to bring in socialization for the purposes of your study, as socialization is not a variable in your proposed design, nor does it sound like you'll be making any generalizations about socialization from your results.

The study I'm considering doing would use a community sample (university students), and as such would use a diagnostic device other than the PCL-R (gold standard in forensic psychopathy diagnosis, but inappropriate for community samples), almost certainly the Psychopathic Personality Inventory (PPI) would be used. It's fairly easy to complete, score and interpret. In line with some studies, I would be using what's called an 'extreme group analysis', where in the top 10% are taken as 'psychopaths' and the bottom 10% as 'non-psychopaths'.

Maybe a potential stumbling block here is your sampling population... I don't know the instrument you plan to use, but I suspect it would have to be pretty sensitive to detect a significant difference in psychopathy among non-incarcerated (and hopefully not extremely psychopathic) college students. Is that something that it can do reliably? If so, then you are in good shape. If not, then you might have a problem creating a big enough difference in the means for statistical power.

Participants will complete a 'game' on a computer, which is described as follows...

1) There are believed to be 3 players, when it is actually only them playing against the computer.
2) Each player can choose to either gain 1 point per trial, or to steal points from other 'players' in set amounts (1, 10, 25, 50), there are 100 trials.
3) Players can only 'mug' one other player per trial.
4) The amount they mug for is directly linked to the probability that they will be revealed as the theif to their victim (1%, 10%, 25% or 50% respectively). Regardless of whether or not they are revealed, the keep what they steal.
5) Participants are told that only those scoring over 100 points at the end will receive the credit point normally given for participating in experiments (they actually get it either way, this is simply a prompt for instrumental aggression)
6) Their current score is always on screen.
7) The participants are never, themselves, robbed.

The hypothesis is that participants scoring high on the Fearless-Dominance and Impulsive-Antisociality factors (analagous to Factors one and two on the PCL-R) of the PPI will show more intense mugging, earlier onset mugging, and more frequent mugging.

I wonder how much trouble you'd have getting this through your IRB? I mean, it's sort of like Milgram's study that revealed to people how vicious and Nazi-like they could be. There would definitely have to be some deception, and you probably couldn't do a full reveal on the debriefing, and I'm not sure you could get an informed consent on that little detail of them not getting credit. Do you have a pretty flexible review board?

One other thing; and I may not fully understand the context of the study, so please set me straight if I'm not interpreting well, but I'm wondering what would be the point of doing a study to show a correlation between a psychopathic personality type and a score on a game that tests tendency toward instrumental aggression (as a psychopathic personality trait)? If the link between psychopathy and instrumental aggression is already as well established as you indicated, then are you testing the PPI for use as a diagnostic or predictive tool? Or is the correlation between instrumental aggression and psychopathy not as definite as I'm thinking?

You might want to try getting permission to access a sampling frame at a prison instead of a college. You will more than likely get a nice sample of psychopaths there. Of course, that might increase the costs of your study, you'd have to pay your participants in cigarettes instead of grade points. (joking... sort of...)