Month: December 2014

How feelings guide threat perception

JolieWormwood
JolieWormwood

“I was scared to death. The last thought I had go through my mind when I pulled the trigger, and I’ll never forget this… was that I was too late. I was too late. And because of that, I was gonna get killed. Worse, my (partner) was gonna get killed” –Officer Bron Cruz

“[He] had the most intense aggressive face. The only way I can describe it, it looks like a demon, that’s how angry he looked.” – Officer Darren Wilson

gun

Lately, policy makers, law enforcers, psychologists and lay people alike have wondered what makes officers shoot and kill young men who are ultimately unarmed. The above quotes, both from police officers who shot and killed unarmed youths in 2014, suggest that emotions play a role in the decision to use deadly force in the field. Of course, it is easy to imagine that having to make a split second, life-or-death decision would cause a person to experience heightened negative emotions such as anger or fear. Yet in my research, my colleagues and I hypothesized that the reverse might also be true: that heightened emotions can causally impact how we perceive and act in potentially life-threatening situations.

In a set of experiments from 2010, Dave DeSteno and I examined whether the experience of particular emotions influenced threat perception.  We first elicited experiences of different emotional states like anger and happiness in participants by having them recall and write about times in their lives that they remembered experiencing a given emotion very strongly. This made participants re-experience those specific emotions. We then had participants complete a simple video game involving the detection of guns. In each trial of our video game, participants were shown a series of background scenes (e.g., a park, a subway station) and then a Caucasian male appeared in the final background scene holding either an everyday object (e.g., a wallet, a soda can) or a hand gun. Participants were given less than a second to identify whether each individual was holding a gun or a neutral object.

Results from five separate experiments revealed that participants made to experience anger exhibited biased threat perception: they were more likely to perceive that the target individual was holding a gun as opposed to a non-threatening object. By contrast, participants in a more neutral mood did not exhibit any bias in threat perception. Importantly, this effect was not related to experiencing just any heightened emotional state. Threat perception performance was not influenced by the experience of a highly activated positive emotion (happiness), a lowly activated negative emotion (sadness), or even another highly activated negative emotion (disgust). It appears that the emotion being experienced needs to be applicable to judgments about potential violent or aggressive threats in order for participants to draw upon that feeling as a source of information for the judgment.

We also demonstrated that the effect of anger on threat perception bias was driven by anger’s impact on participants’ expectancies for encountering threats. That is, participants made to feel angry actually expected that they would encounter more guns in the threat perception task than did participants in a more neutral mood, and it was this heightened expectancy for guns that drove the observed differences in perception.

So how can this research be applied to the real world? Our findings suggest that emotions play a critical role as police officers and other law enforcers weigh life or death decisions in the field. Fortunately, our findings also suggest a viable means for intervention. We found that we could eliminate the effects of anger on biased perceptions by telling angry participants how many guns they should actually expect to see in the experiment. When participants knew that the average target wasn’t likely to be carrying a gun, they were less likely to let their anger bias their perception.  This suggests that providing law enforcement personnel better information about the actual likelihood of threats in their area may help them make snap decisions accurately, increasing efficacy while reducing collateral harm.

 

photo credit: https://www.flickr.com/photos/bnorthern/115132826/

The Social Brain: Thinking about Others

Steve Chang
Steve Chang

Our lives are greatly dependent on other people around us. As the holiday seasons approach, many of us are reminded that there are so many people whom we care about and who care about us. For some people, this time of the year may remind them of the loved ones who might no longer be around them. We are highly social animals, and we cannot escape this fact. Sociality creates, defines, and drives who we are.

Many scientists agree that the complexity of social environments was one of the key factors that actively steered primate brain evolution. This is of course supported by a seminal hypothesis known as the social brain hypothesis by Robin Dunbar. This hypothesis was primarily generated by the observations that there is a strong positive correlation between the brain size and the social group size across different primates (monkeys, apes, and humans). In a nutshell, larger the social group size became, the bigger the brain size became. It’s definitely not a stretch to state that social processing is one of the very most important functions carried out by our brains (especially in the parts of our brain called neocortex).kids playing

Animals that live in social groups are indeed very sensitive to information about other individuals in their societies. Processing social information can take many forms. Just to give some everyday examples, we constantly pay attention to what other people think of us, and vice versa. We are also very aware of things happening to others. We often feel happy, sad, angry, or jealous when we learn about others. Basically, it’s up to our brain to parse out the information about self and others in order to influence our future actions. Not surprisingly, this process is powerfully shaped by emotional feelings generated by different social information.

Neuroscientists are now hoping to unlock the mystery behind the “social brain”. This is a daunting task especially since social processing, by nature, is a product of numerous associations among sensory/motor, cognitive, and emotional processes. One of the big questions that many neuroscientists are asking is whether there are dedicated brain circuits for social processing. The alternative is that the neural circuits already being used for non-social processing also handle social functions. The answer still remains elusive, but the experiments asking questions about the social brain are becoming more sophisticated and more rigorous (which is exciting). We recently discussed how preexisting brain areas for carrying out non-social functions might have been repurposed and extended to serve social functions in primates. It remains to be seen whether some parts of the brain are newly expanded to accommodate exclusively social functions.

Let’s return to how the brain might process the information about others. In a recent study, we tested how the neurons in the brain that carry the information about one’s rewards (e.g., getting money, delicious food, etc.) respond when another individual is rewarded. In a task where monkeys got to choose whether they shared a reward with another monkey, we found that different parts of the prefrontal cortex (an area of the brain that is highly developed in humans and other primates) signal juice rewards received by an actor monkey and a recipient monkey in distinctive manners. Some neurons only care about one’s own reward outcome, but there are also other types of neurons that track the reward outcome of another individual either exclusively or in conjunction with one’s reward outcome. In another recent study, Matt Roesch and colleagues found that when a rat observes the rewarding event of another rat, dopamine is released in a brain region important for reinforcement learning. One important conclusion to be made from these and other recent studies (e.g., a, b, c) is that the brain structures that typically process one’s own information also signal the information of other individuals either by the same neurons or distinct “other” types of neurons.

The field investigating the mystery behind the social brain is rapidly growing. It would be fascinating to know more about how internal states, such as those regulated by emotion, control the way by which social information is computed. The success of our adventures into the social brain will critically depend on collective efforts by scientists who study human participants and non-human animals so that we can discover the complexities behind human social cognition as well as concurrently discover fundamental neuronal mechanisms in animal models. New exciting knowledge awaits us.

 photo credit: https://m.flickr.com/#/photos/kymberlyanne/2687290741/