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No voodoo, just can- and of brain scanning NO THANKS, I JUST IMAGINED EATING SOME If your snack-based new year’s resolutions are already failing, you could try applying the lessons from a new study by psychologists at Carnegie Mellon University. Carey Morewedge and his colleagues showed that imagining repeatedly eating a specific food led participants to subsequently eat less of that food when given the opportunity (Science: tinyurl.com/5vgn7gu). Across five experiments, Morewedge’s team found that participants who imagined eating 30 chocolate sweets subsequently ate fewer sweets from a bowl than control participants who imagined eating just three of them, or control participants who imagined inserting 30 quarters into a laundry machine. The effect was specific – imagining eating the chocolates did nothing to reduce participants’ subsequent consumption of cheese. The researchers think the effect occurs via habituation. After imagining eating lots of cheese cubes, participants worked less hard at a simple computer game in which they could earn points in return for cheese. Yet their self-reported liking of cheese remained unchanged by the imagination task. In other words, the participants’ motivational drive to obtain the food was attenuated even while their liking was unaffected, which is indicative of habituation. ‘The results show that top-down processes can enact habituation in the absence of pre-ingestive sensory stimulation,’ the researchers said. ‘The difference between actual experience and mental representations of experience may be smaller than previously assumed.’ CJ I For more ways to be good, see Christian Jarrett’s feature on the psychology of sin on p.98
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The brain scanner – has it provided a window into the mind as so many claimed it would? Or is it little more than an expensive toy? Brain-imaging labs attract generous grants and their output is published in high-impact journals. But in 2009 a paper surfaced prior to publication (tinyurl.com/34mp83u; see News, February 2009) in which Ed Vul and his colleagues claimed that numerous neuroimaging studies in social neuroscience had deployed iffy statistical methods, leading them to identify ‘voodoo correlations’ between psychological states and regions of brain activity. The charge caused a storm of controversy and the paper, when it finally came out in print, had been renamed with a less provocative, voodoo-free title. Now the dust has settled, the same journal, Perspectives in Psychological Science, has published a special issue on what brain imaging can and can’t tell us.
In the lead article, Gregory Miller of the University of Illinois, himself a user of brain-imaging techniques, is highly critical of ‘naive’ reductionists who claim that psychological phenomena are somehow based in brain processes or located in particular neural structures. ‘Functions do not have a location,’ he writes, adding later, with reference to a particular study on voters: ‘Trust decisions and political attitudes do not occur in the brain. Decisions, feelings, perceptions, delusions, memories do not have a spatial location. We image brain events… We do not image, and cannot localise in space, psychological constructs.’ Miller reminds readers that brainimaging studies are only able to provide correlations between brain activity and psychological processes and that how each affects the other, if at all, remains largely mysterious. He also reminds us that although many researchers act as though the neural is somehow more
NO-TRICKERY PLACEBO To harness the power of the placebo effect with an inert pill, doctors must take the morally dubious step of tricking their patients into thinking the pill has an active ingredient. Or must they? The first study of its kind, led by Ted Kaptchuk at Harvard Medical School, suggests not, at least not when dealing with patients with irritable bowel syndrome (PLOS One: tinyurl.com/2et68az).
Kaptchuk and his colleagues randomly allocated 37 patients with IBS to receive two inert pills twice daily and 43 to act as no-treatment controls. The former group were told the pills had no active ingredient and were further informed that: ‘placebo pills, something like sugar pills, have been shown in rigorous clinical testing to produce significant mind–body self-healing
processes’. Before the group allocation, all patients were talked through the benefits and power of the placebo effect by a physician, including the fact that taking the pills is critical for the effect to work. The researchers took care to ensure that patient–physician contact time and quality was similar across the two groups. Amazingly, the
vol 24 no 2
february 2011