Dr. David Amodio has graciously taken the time to respond to many of the criticisms of his paper, Neurocognitive correlates of liberalism and conservatism, made by The Neurocritic and others. [EDIT: His comments first appeared here, and I have taken the liberty to repost them as a new entry.]
Hi Neurocritic,And here is my reply.
I like your blog – it’s important to a have a critical voice out there. However, given how this study has been misconstrued and sensationalized in the media, as well as among science bloggers, it’s important to address the criticisms directly. Though I’ve generally not worried about the “lay” coverage (how can you argue science with pundits?), it might be worthwhile to respond to a blog that is read by neuroscientists (including myself from time to time):
1) There were no gender differences on any variable. Moreover, 63% women is actually fairly balanced for a psychology study, so I’m surprised this has even come up. We didn’t report gender effects for the sake of brevity, though in hindsight, I wish we had slipped it in.
2) People have complained that there were more liberals the conservatives in the sample. True, in an absolute sense. But this is typical in political psychology: Americans are more conservative on average, and so more extreme conservatives usually rate themselves as moderate conservatives, whereas moderate liberals tend to rate themselves more extremely (see Linda Skitka’s work and comments on the paper). It’s a scaling issue that psychologists deal with all the time.
Nevertheless, we’re talking about a correlation. The clear linear effect suggests the stronger liberalism is associated with greater conflict-related ACC activity. Not sure how anyone can argue with that.
3) The sample was actually rather large for a neuro study. Also, please note our use of *inferential statistics* – I’ve been surprised by the criticism of the size given the strength of the effect!
4) Outliers? There weren’t any. (Not sure what Broussard was referring to in the highly-critical comment you posted. Maybe someone should lend him a stats book…)
5) On reporting group differences in RTs and error rates – to be clear, we did not conduct group analyses (though one graph displays the median split of ERN waves). We looked at correlations along a continuum. Group analyses would have been psychometrically problematic, and furthermore, we didn’t want to suggest that political orientation is categorical. Though of course this didn’t stop the media and bloggers to speak in terms of categories…
In the end, the study reports a correlation. You can’t “disprove” it – you can only interpret it. Our interpretation was face valid – this measure of political orientation was strongly correlated with the ERN and No-Go N2 from the Go/No-Go task. Simple as that. Might there be 3rd variables at play? Probably. But that doesn’t contradict our interpretation or cast doubt on the quality of the study.
Good science is an art. But so is good science critique. Without a plausible alternative interpretation, you don’t have a critique. I suppose people are just cranky because this bullet-point of a study has been so over-sensationalized. Or maybe some folks just aren’t familiar with how you do this kind of research. So I hope this post clarifies some things.
Thank you for taking the time to respond and for being so gracious despite some...well...highly critical remarks. Some of which are not my own, so perhaps I should not have been such a "sounding board." I just have a couple of replies to your comments.
1) I (personally) didn't have an issue with possible gender differences, but it's good to have that clarified.
2) I'm rather ignorant of standard rating systems in political psychology, but is self-rating always used? Aren't there more "objective" questionnaires used to classify American participants along the liberal-conservative continuum?
I'm not familiar with Linda Skitka's work. I wouldn't know where to start [even if I had time to read her papers], perhaps with Skitka & Tetlock (1993)? 1 [Hmm, Mullen et al. (2003) looks quite interesting, if not entirely relevant here.]
3) Your correlations are strong, yes. It seems people had more of a problem with the restricted range of the conservative sample.
4) You're right, he's wrong, not sure which points would be considered outliers. I went back to the original post and put the offending passages in strikeout font. However, it does seem the 7 conservatives' ERNs were quite variable (values from -2 to -23).
5) I was basing my comments about group analyses on the fact that you had to do them to show the EEG data in Figure 1b. And the fact that mean accurate rates were reported in (ahem) newspaper articles. My criticism about the lack of RT data in the paper still stands:
There was absolutely no information about RTs at all, so we don't know whether there was a speed-accuracy trade-off in the conservatives (a reckless and disinhibited response style) or whether they were "conscientious" (RT comparable to [or slower than] liberals), but just couldn't stop themselves from pressing the key on No-Go trials.That could comprise part of an alternate explanation, along with "3rd variables at play" as I've sarcastically suggested with my Liberals Are Neurotic and Conservatives Are Antisocial quip.
At any rate, I would beg to differ that good science critique must provide an alternate interpretation. Some science critique can be based on methods, analysis, reporting of results, etc. Standard peer-review stuff.
My closing remarks are based on the assumption that the error-related negativity (ERN) brain wave is a direct measure of conflict monitoring in the anterior cingulate cortex (ACC). [I've focused on the ERN rather than the N2 because the former is illustrated in the paper and the latter is not.] A quick review of the literature indicates that's not necessarily the case. First, not everyone agrees that the ERN measures response conflict rather than error processing more specifically (Carbonnell & Falkenstein, 2006), or that ACC hemodynamic activity during error commission is a reflection of response conflict (Critchley et al., 2005; Garavan et al., 2003). Second, when people make mistakes, it seems that more of the brain is active than just the ACC (Klein et al., 2007; Ullsperger & von Cramon, 2006).
At least, these are my impressions...
To measure the cognitive conservatism and liberal-humanism factors identified in earlier research (high scores on dogmatism, authoritarianism, and identification with the political right; Skitka & Tetlock, 1992) we adopted Altemeyer's (1981, 1988) 30-item balanced Right-Wing Authoritarianism (RWA) scale. The RWA scale is an updated measure with sound psychometric properties (see review by Winter, 1990) that we judged to be superior to the scales we used in earlier studies of ideo-affective resonances. The scale ranges from liberal-democrat to authoritarian (see Altemeyer, 1988, p. 263). Altemeyer (1981) reported Cronbach's alpha of .88 for a sample of 965 University of Manitoba students. We observed an alpha of .86 with the present sample, indicating adequate internal consistency in measuring the construct.
Carbonnell L, Falkenstein M. (2006). Does the error negativity reflect the degree of response conflict? Brain Res. 1095:124-30.
Critchley HD, Tang J, Glaser D, Butterworth B, Dolan RJ. (2005). Anterior cingulate activity during error and autonomic response. Neuroimage 27:885-95.
Garavan H, Ross TJ, Kaufman J, Stein EA. (2003). A midline dissociation between error-processing and response-conflict monitoring. Neuroimage 20:1132-9.
Klein TA, Endrass T, Kathmann N, Neumann J, von Cramon DY, Ullsperger M. (2007). Neural correlates of error awareness. Neuroimage 34:1774-81.
Mullen, E., Bauman, C. W., & Skitka, L. J. (2003). Avoiding the pitfalls of politicized psychology. Analyses of Social Issues and Public Policy, 3, 171-176.
This article provides two arguments for using caution when interpreting the results of a Global Change Game simulation indicating that people high in right-wing authoritarianism are particularly likely to bring the world to ruin. First, we review research that demonstrates that extremists on both the political left and right share characteristics likely to be associated with poor performance in the Global Change Game (e.g., lower levels of integrative complexity) and that there are reasons to be cautious about letting political extremists on either the left or right inherit the earth. Second, we caution that political psychologists need to be aware of how their own values shape the types of research they conduct and the inferences they draw from that research and that the same results can be construed very differently depending on the lens through which they are viewed.
Skitka, L. J. & Tetlock, P. E. (1993). Providing public assistance: Cognitive and motivational processes underlying liberal and conservative policy preferences. Journal of Personality and Social Psychology, 65, 1205 - 1223.
Previous research in a wide variety of policy domains (e.g., azidothymidine for AIDS patients, low-income housing) has indicated that under no scarcity, liberals tend to help all claimants for assistance, whereas conservatives withhold assistance from people who are personally responsible for their predicament (Skitka & Tetlock, 1992). Three studies explore 6 explanations for this robust finding: deterrence, self-interest, punitiveness, mindlessness, value orientation, and avoidance of trade-off reasoning. The findings shed light on both the cognitive strategies and motivational priorities of liberals and conservatives. It was discovered that liberals are not mindlessly egalitarian, but try to avoid socially awkward value trade-offs that require placing monetary values on lives. By contrast, conservatives are motivated to punish violators of social norms (e.g., deviations from traditional norms of sexuality or responsible behavior) and to deter free riders.
Ullsperger M, von Cramon DY. (2006). The role of intact frontostriatal circuits in error processing. J Cog Neurosci. 18:651-64.
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