March 15, 2013
Creative Task Performance Improved By Turning Off Brain’s ‘Filter’
Alan McStravick for redOrbit.com — Your Universe Online
As you are reading these words, your ability to comprehend their meaning is being aided, in no small part, by your brain´s prefrontal cortex. This region of the brain is helping you to maintain focus from sentence to sentence and is filtering out irrelevant thoughts, perceptions and memories. It is this thought filtration that allows you to complete a task without thoughts of when the water bill is due creeping in.
The study, published in the journal Cognitive Neuroscience, builds upon previous studies that have established the functionality of the prefrontal cortex as a center supportive of cognitive control. More specifically, the left prefrontal cortex does most of the heavy lifting in this department. Study leader and Christopher H. Browne Distinguished Professor of Psychology and director of the Center for Cognitive Neuroscience, Sharon Thompson-Schill, and her colleagues and collaborators wanted to test whether or not effectively diminishing cognitive control could be beneficial when completing certain tasks. Assisting in the study were Evangelia Chrysikou of the University of Kansas, Roy Hamilton and H. Branch Coslett of the UPENN Perelman School of Medicine, and Abhishek Datta and Marom Bikson of the Department of Biomedical Engineering at the City College of New York.
To aid in their study, the team devised an experiment where participants would be shown pictures of 60 common, everyday items. In the nine seconds the object would be visible, the subjects were asked to provide a use for the item that would be considered unorthodox. For example, if shown a picture of a baseball bat, a subject might suggest it could be used as a rolling pin. The research team wanted to measure the time it took for the subjects to provide a valid response, or if they were even able to do so, before the next picture appeared.
The research team was working from the hypothesis that an elevated level of cognitive control would stifle the creativity needed to think of an uncommon use for a common object.
“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.”
The method devised for this experimentation was, until relatively recently, not possible. This is because the ability to monitor and inhibit activity in the brain had required techniques that were fairly invasive. As of late, new ways of non-invasively manipulating neurons in specific areas of the brain have been developed. This allows researchers to induce a variety of temporary changes in both perception and performance.
Specifically, the method employed by Thompson-Schill´s team is known as transcranial direct current stimulation, or tDCS. This technique utilizes a weak electrical charge that is directed to pass through the brain, with the charge being aimed in such a way that its path intersects with areas thought to be associated with a specific ability or behavior. The electrical charge can also influence the electrical activity that constitutes cell-to-cell communication in those areas as well.
“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.”
Once the subjects for the study had been selected, they were split into groupings that corresponded to three experimental conditions. The first group was to receive tDCS to their left prefrontal cortex for the entirety of the task. The second group would have tDCS administered to their right prefrontal cortex. And the third group would receive what, according to the research team, would amount to a placebo. As tDCS produces a slight tingling sensation on the scalp when first applied, the placebo group received an abbreviated stimulation just before the task began, rather than receiving stimulation throughout the task.
Creating sub-groups within the three subject groups, the team had one half of each method group perform the uncommon-use task with the other half simply stating what each object might usually be used for. Additionally, each participant in the study was asked to complete a task involving the memorization of a string of numbers. The memorization task is a common exercise in psychological experimentation that is known not to require the prefrontal cortex.
“We wouldn´t want to think that the stimulation affected everything,” Thompson-Schill said. “So if we found an effect when participants were remembering numbers, we´d be worried about our interpretation of the data.”
The team´s hypothesis was bolstered when, in fact, none of the experimental conditions were shown to have affected the study participants´ performance when asked to recall the number sequences. Also, the subjects asked to state the common uses of the objects presented were unaffected as well.
However, the subjects in the group receiving left prefrontal cortex stimulation when completing the uncommon-use task presented an impressive difference over those not receiving stimulation.
It was determined that participants receiving either the right prefrontal cortex stimulation or the placebo were unable, on average, to provide uncommon uses for 15 of the 60 objects presented. However, those participants receiving the left prefrontal cortex stimulation were stumped on only eight of the objects.
Additionally, the left prefrontal cortex stimulation group was able to provide their creative uncommon-use answers a full second faster than the other two groups. “A second faster difference is huge in psychology research,” claims Thompson-Schill. “We´re used to seeing differences measured in milliseconds. This is probably the biggest effect I´ve seen over my 20 years in research.”
The team suggests their results support the idea that elevated levels of cognitive control may be detrimental in some circumstances. Specifically, they cite the diminished cognitive control exhibited by humans in early development.
Thompson-Schill stated, “We differ from non-human primates in having a long period of immaturity in our prefrontal cortex, so we started considering whether this might not be an unfortunate accident of nature but rather a feature of our species´ developmental path.”
The team contends it is this slow development of the prefrontal cortex that explains why young children are often unable to complete attention based tasks. On the other hand, tasks requiring a vivid and lively imagination are performed with ease. Additionally, with the rapid introduction of new objects and situations, the researchers believe the diminished cognitive ability of children aids them in being able to acquire and process new knowledge.
“There are things that are important to not filter, in particular when you are learning,” Thompson-Schill said. “If you throw out information about your environment as being irrelevant, you miss opportunities to learn about those things.”