Humans and monkeys of one mind when it comes to changing it

June 19, 2014
Wild Capuchin monkey (Cebus capucinus), on a tree near a river bank in the jungles of Guanacaste, Costa Rica. Image: David M. Jensen/Wikipedia.

Covert changes of mind can be discovered by tracking neural activity when subjects make decisions, researchers from New York University and Stanford University have found. Their results, which appear in the journal Current Biology, offer new insights into how we make decisions and point to innovative ways to study this process in the future.

"The methods used in this study allowed us to see the idiosyncratic nature of decision making that was inaccessible before," explains Roozbeh Kiani, an assistant professor in NYU's Center for Neural Science and the study's lead author.

The study's other authors included Christopher Cueva and John Reppas of Stanford's Department of Neurobiology and William Newsome, who holds appointments at the university's Department of Neurobiology and at the Howard Hughes Medical Institute at Stanford's School of Medicine.

Previous work on the decision-making process—a plan of action based on evidence, prior knowledge, and payoff—has been methodologically limited. In earlier studies, scientists analyzed one neuron at a time, then averaged these results across neurons to develop an understanding of this activity. However, such a measurement offers only snapshots of neurological behavior and misses the fine-scale dynamics that lead up to a decision.

In the Current Biology study, the researchers examined many neurons at once, giving them a more detailed understanding of decision making.

"Now we can look at the nuances of this dynamic and track changes over a specified period," explains Kiani. "Looking at one neuron at a time is 'noisy': results vary from trial to trial so you cannot get a clear picture of this complex activity. By recording multiple neurons at the same time, you can take out this noise and get a more robust picture of the underlying dynamics."

The researchers studied , running them through a series of tasks while monitoring the animals' neuronal workings.

In the experiment, the monkeys viewed a patch of randomly moving dots on a computer screen. Following the stimulus, monkeys received a "Go" signal to report the motion direction by making an eye movement. The scientists sought to predict the monkeys' choices purely based on the recorded neural responses before the Go signal. Their model achieved highly accurate predictions.

The same model was then used to study potential dynamics of the monkeys' decision at different times before the Go signal. The scientists confirmed these predictions by stopping the decision-making process at arbitrary times and comparing the model predictions with the monkeys' actual choices.

Surprisingly, the ' decisions were not always stable. Occasionally, they vacillated from one choice to another, indicating covert changes of mind during . These changes of mind closely matched the properties of human changes of mind, which were uncovered in a 2009 study. They were more frequent in uncertain conditions, more likely to correct an initial mistake, and more likely to happen earlier during a decision.

The research was supported by the Howard Hughes Medical Institute, the Air Force Research Laboratory (FA9550-07-1-0537), a Berry Postdoctoral Fellowship, and a Sloan Research Fellowship.

Explore further: Brain cell mechanism for decision making also underlies judgment about certainty

Related Stories

Recommended for you

How cells 'climb' to build fruit fly tracheas

November 25, 2015

Fruit fly windpipes are much more like human blood vessels than the entryway to human lungs. To create that intricate network, fly embryonic cells must sprout "fingers" and crawl into place. Now researchers at The Johns Hopkins ...

How cells in the developing ear 'practice' hearing

November 25, 2015

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular ...

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.