"When we use objects in daily life, our cognitive control helps us focus on what the object is typically used for and 'filters out' irrelevant properties," Chrysikou said. "However, to come up with the idea of using a baseball bat as a rolling pin, you have to consider things like its shape and the material it's made of."
"The real takeaway," Thompson-Schill said, "is that when you give people a task for which they do not know the goal such as showing them an object and asking, 'What else can you do with this thing' anything that they would normally do to filter out irrelevant information about the object will hurt their ability to do the task."
Experiments to test such hypotheses have been aided by new ways of non-invasively manipulating neurons in specific areas of the brain, inducing a variety of temporary changes in perception and performance.
The method Thompson-Schill's team used, called transcranial direct current stimulation, or tDCS, involves passing a weak electrical charge through the brain, aiming the charge's path so it intersects with areas thought to be associated with an ability or behavior. This charge can influence the electrical activity that constitutes cell-to-cell communication in those areas.
"TDCS is believed to induce incremental shifts in the electrical potential of neuronal membranes, making it more or less likely that neurons will reach their threshold for firing," Hamilton said. "In this instance, we employed stimulation in a way that would make it harder for neurons to fire, thereby diminishing behaviorally relevant activity in that part of the brain."
Participants were first split into groups corresponding to three experimental conditions: one would receive tDCS to their left prefrontal cortex for the duration of the task, another would receive it to their right prefrontal cortex and a third would receive what amounted to a placebo. TDCS produces a slight tingling sensati
University of Pennsylvania