Chocolate? 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.'

--Christian Jarrett