Neuroscientist Richard Davidson is perhaps best known for having helped to topple the once widely accepted scientific dogma that after we leave adolescence behind, our brains become forever fixed. As a pioneer of the study of adult brain plasticity, he’s also spent years pinpointing the measurable effects of meditation on the brain, and investigating concrete ways in which people can be trained to take better control of common mental irritations like intrusive thoughts, negative emotions, and a wandering attention span.
The common theme that ties all of this research together is a deep interest in the tight, complex relationship between our minds and our bodies. In his experiments on the neural substrates of emotional states, for instance, Davidson has tried to figure out what specific patterns of brain activity are associated with feelings like anger, sadness, desire, or joy, as well as with personality traits like resilience and self-awareness.
Davidson has also examined how powerful emotional experiences interact with other neuropsychological functions. In 2011, his laboratory published an inventive study relating stress to visual cognition. The study’s 32 participants were asked to perform a simple visual task—keeping their attention on a series of target arrows that pointed either up or down, without being sidetracked by distractor icons that popped up on either side. The goal was to press the corresponding up or down arrow on a keyboard whenever a target appeared.
The heart of the experiment, though, was the following: Participants agreed to receive brief electric shocks to their fingers, delivered at random moments during blocks of time the researchers called “threat blocks.” During “safety blocks,” participants knew they would be completely unplugged from the electrode stimulator. The shocks weren’t physically harmful, but they certainly hurt.
Now it was time to look at scans of electrical activity in each subject’s brain over the course of the experiment. The stress of anticipating and experiencing shocks during threat blocks, wrote Davidson’s colleague Alexander Shackman in a report on the study, “potentiates early and attenuates late stages of visual processing.” In other words, tension or anxiety heightened people’s immediate sensory responses to the on-screen targets—they gathered information about the orientation of the target arrows more quickly and accurately. But stress also dampened people’s subsequent task-related performances—they weren’t as fast at actually pressing the keys in response to the stimuli. (As a result of these conflicting effects, subjects’ mean performance remained about the same during threat blocks as during safety blocks.)
These findings are complicated, but not impossible to make sense of. We evolved, it seems, to be extremely sensitive to sensory signals of potential threats in stressful environments. Our brains are very good at automatically picking up on the presence of danger. But once we’re in a state of stress, it may be that we shift into a more evaluative, cognitive mode of processing that prioritizes slightly slower decisions.
To hear about Davidson’s latest scientific insights, join him in a session on human emotions with psychologist Paul Ekman and physician Esther Sternberg this Saturday in San Francisco, during the second annual Being Human event. And if you can’t make it, we invite you to bring both mind and body to our live online streaming of the conversation.