Here’s what they found. In the brains of the students who received negative feedback the sympathetic nervous system lit up. This is the “fight or flight” system, the system that mutes the other parts of the brain and thus allows us to focus only on the information most necessary to survive. When this part of the nervous system is triggered, your heart rate goes up, endorphins flood your body, your cortisol levels rise, and you tense for action. This is your brain on negative feedback: it responds as if to a threat, and it narrows its activity. The strong negative emotions produced by criticism “inhibits access to existing neural circuits and invokes cognitive, emotional, and perceptual impairment,” psychology and business professor Richard Boyatzis said in summarizing the researchers findings.

Negative feedback doesn’t enable learning. It systematically inhibits it and is, neurologically speaking, how to create impairment.

In the students who received attention focused on their dreams and how they might go about achieving them, however, the sympathetic nervous system was not activated. Instead it was the parasympathetic nervous system that lit up. This is sometimes referred to as the “rest and digest” system. To quote the researchers again: “[T]he Parasympathetic Nervous System . . . stimulates adult neurogenesis (i.e., growth of new neurons) . . . , a sense of well being, better immune system functioning, and cognitive, emotional, and perceptual openness.”

In other words, positive, future-focused attention gives your brain access to more regions of itself and thus sets you up for greater learning. We’re often told that the key to learning is to get out of our comfort zones, but this finding gives the lie to that particular chestnut—take us out of our comfort zones and our brains stop paying attention to anything other than surviving the experience. It’s clear that we learn most in our comfort zone, because that’s our strengths zone, where our neural pathways are most concentrated. It’s where we’re most open to possibility, and it’s where we are most creative and insightful.

Rather than informing an appropriate course of action, the more immediate, visceral, intensely powerful, emotional - possibly blunter - response can overwhelm the slower, more elaborately calibrated, evaluative system. We become paralysed by fear. We lose a sense of control and panic ensues. Our thoughts are distorted and we become disorganised by fear. In this frenzied state of mind we cannot respond to reason.

Loneliness is more pervasive than ever before, and our ancient brains, designed to seek the safety of groups, experience those negative feelings as life-threatening, which leads to stress and sickness.

Summarizing their own and other’s research, a distinguished group of Canadian psychologists led by Toni Schmader (Schmader, Micheal Johns, and Chad Forbes) points to three things that typically happen when people are under this threat. First, they’re stressed. Their heart rate, blood pressure, and sweating are elevated. Activity in their prefrontal cortex is often suppressed— which makes it more difficult to control attention, thinking, emotions, and behaviour. It’s harder to engage in the task at hand. Second, they’re self-conscious. The exhort themselves to double down, to disprove the stereotype. Then they monitor themselves to see if their efforts are working. Third, they try to suppress negative thoughts that, if allowed to surface, would deepen their sense of threat.

They exposed people to loud noise, then measured their reactions— psychological and physiological— to see how much stress it caused. Half of the participants were given a way of coping: a red button on their desk that they were told could lower the noise. The other half experienced the noise with no red button, no way of coping. By this time, the literature was clear on a major point: the mere knowledge that one has a way of coping with a stressor can reduce its impact.