On magnets and lies, and checking sources

The historian’s attitude, when attempting to establish matters of fact, toward the sources, is one of tempered but universal skepticism. The same applies to the history of the present. For example:
Don’t depend on popularizations for your knowledge of neuroscience (see the previous item in this blog for a similar issue concerning the biology of sex). A recent headline in several newspapers and online sources reads something like this: “Magnetic Pulses To The Brain Make It Impossible To Lie”. Wow! That’s exciting! And scary too…
The only problem is, it’s false. The original study, which takes two minutes to retrieve if you have access to the journal (Behavioural Brain Research, Volume 225.1 (Nov 2011) 209-214; doi:10.1016/j.bbr.2011.07.028) states its main result as follows:
In our study we found support for the general hypothesis: rTMS targeted at DLPFC changed spontaneous truth-telling/lying rate in a task with no mock-criminal, guilty knowledge, or personally relevant information processing contexts being involved. Importantly, clear hemispheric differences were found. In principle, artificial inhibition of the sustained neuronal activation-states in left DLPFC and possibly the concomitant effect on the systems intimately associated with DLPFC decreases the willingness to tell the truth (more non-truthful answers produced) and/or increases the willingness to tell lies. Conversely, inhibitory rTMS effect on right DLPFC and possibly the concomitant secondary effect on the DLPFC-associated systems increases willingness to tell truth (more truthful answers produced) and/or decreases willingness (or capability) to lie.
[Acronyms unpacked: rTMS = repetitive transcranial (from outside through the skull) magnetic stimulation; DLPFC = dorsolateral prefrontal cortex.]
The authors carefully note the limitations of their study.
  • The effects of the magnetic stimulation may spread beyond the area adjacent to the coil; and so “ interpretations on causal effects of TMS exclusively through the TMS-targeted area should be taken with care”.
  • The dorsolateral prefrontal cortex has many functions, and in a complicated task like “spontaneous” lying more than one may be activated: because “perceptual stimuli had to be named and two response variants chosen and reversed from time to time, the number of possible neural mechanisms that influence readiness to lie in our task and their possible interactions remain too numerous at present” to be sorted out.
  • The spontaneity of the lying was limited to some unknown degree. Subjects were “instructed to name the colour correctly or just lie about it, naming the other colour that was not presented in this trial, being free to choose whether to lie or not”, but they were also told that only lying or only telling the truth would not be “good for the experiment”.
The upshot is that there is a positive correlation between spontaneous truth-telling and rTMS stimulation of the right dorsolateral prefrontal cortex; and between spontaneous lying and stimulation of the left DLPFC. That’s very interesting. But it’s far from what you would gather from the headlines and stories online.
The moral should be obvious. In matters of science, there is no substitute for reading the original studies. Science journalists, and for that matter popularizing philosophers, should be drawn upon cautiously. Moreover, the studies often present complexities and issues (as here) that summaries, especially of the ax-grinding sort, tend to omit.
I learned this long ago when reading studies on animal perception that were cited over and over in the philosophical literature on representation. It was clear that only a few people had read the original studies; everyone else drew on their predecessors’ summaries. When I read the original studies, I discovered not only mistakes in the summaries but also a world of fascinating work that the “poor diet of examples” in the literature had simply omitted. Insect senses in particular offered much food for thought, and I recommend it highly if you’re thinking about the origins of representation or defining sensory modalities.
Philosophers have done a better job in the last twenty years. A much broader range of scientific results is brought to bear on philosophical debate, and prejudices according to which doing so is somehow unphilosophical have waned. Experimental Philosophy even generates its own results. But it’s well worth remembering, both when doing philosophy and when judging scientific results of political import, that although a great deal of expertise is required to contribute to ongoing research, rather less is needed to acquire a basic understanding of the results of research, to understand their limitations, and to evaluate second-hand accounts.

LinkSeptember 9, 2011 in NewAPPS · Psychology · Science · Society