The new study goes a step further, showing that there seem to be ways to help kickstart the dlPFC through the use of what Hare calls "external cues" that allow us to exhibit more self-control than we might have otherwise.
The researchers came to their conclusions based on data from a brain-imaging experiment conducted with 33 adult volunteers, none of whom were following a specific diet or trying to lose weight for any reason. Each of the volunteers was shown 180 different food itemsfrom chips and candy bars to apples and broccolithrough a set of video goggles while in a functional magnetic resonance imaging (fMRI) machine.
The hungry subjectsthey were asked to fast for at least three hours prior to the experimentwere given up to three seconds to respond to each picture with a decision about whether or not they'd want to eat the food shown after the experiment was over. They could either give the food a "strong no," a "no," a "yes," or a "strong yes." Once all of the images had been flipped through, a single food image was chosen at random; if the volunteer had said "yes" or "strong yes" to the idea of eating that food, he or she was served that item.
"Because only one random trial was selected to 'count,'" says Rangel, "the optimal strategy for subjects is to treat each decision as if it were the only one."
Simple, right? But here's the catch: before every 10 food choices, an instruction would come on the screen for five seconds telling the subjects either to "consider the healthiness," "consider the tastiness," or "make decisions naturally." This meant that of the 180 decisions, the subjects made 60 in each of the three "instruction conditions."
What this was meant to do, Rangel explains, is shift the subject's attention during the experiment and, potentially, shift the way in which they made decisions.
Afterwardoutside the scannerthe subjects were asked to rate th
|Contact: Deborah Williams-Hedges|
California Institute of Technology