How brain structure and heartbeat affect your judgement
The structure of our brain controls our behaviour, but we think with our hearts more than our heads.
Most of the time, we think with our heads, but occasionally, especially in moments of distraction, we unconsciously switch to thinking with our hearts. We do this far more than we know, or care to admit.
Our heart rate fluctuates many times every day, even during calm conditions such as sitting or lying down and these fluctuations can affect the way we think. Without realising it, our heartbeat works hand in hand with our thinking processes to help us come to terms with and make reasonable decisions about social issues.
Scientists at the University of Waterloo, Canada, and the Australian Catholic University have tried to identify the conditions under which psychophysiology can affect the cognitive basis of wisdom and judgement.
They found that people who have greater heart rate variability and who are able to think about social problems from a distanced viewpoint demonstrate a greater capacity for wise reasoning. In other words, the physiology of the heart – specifically, the variability of heart rate during low physical activity – relates to less biased and wiser judgment.
There’s a growing consensus among scientists that wise judgment includes the ability to recognize the limits of one’s own knowledge, the ability to understand others’ points of view and the ability to seek reconciliation of opposing viewpoints.
Participants in the study were instructed to reflect on a social issue from a third-person perspective. People with more varied heart rates were found to be more capable of reasoning in a wiser, less biased fashion. But when the participants were instructed to reason about the issue from a first-person perspective, no relationship between heart rate and wiser judgment was apparent.
Specialists in this area already know that people with greater variation in heart rate show superior performance in the brain’s executive functioning, such as working memory. But that doesn’t necessarily mean that these people are wiser – some people may use their cognitive skills to make unwise decisions. In order to harness one’s cognitive abilities for wiser judgment, people with greater heart rate variability first need to overcome their egocentric viewpoints.
The study was published in the journal Frontiers in Behavioural Neuroscience.
Heart rate aside, it researchers also believe that people who act impulsively and who are prone to thrill seeking may have less grey matter, that is, the wrinkly outer layer of the cerebral cortex.
Scientists led by Professor Avram Holmes of Yale University, together with researchers from Harvard and Massachusetts General Hospital, used magnetic resonance imaging (MRI) to scan the brains of more than 1,200 men and women aged between 18 and 35.
They measured the size and volume of specific regions of each participant’s brain, and then compared them with the results of a questionnaire about their behaviour. They were asked about their impulsiveness and their need for ‘novel and intense’ or sensation-seeking experiences, their willingness to take risks, and whether or not they were prone to making rapid and impetuous decisions. They were also asked about their use of alcohol, tobacco, and caffeine. None of the volunteers had any history of substance abuse.
The scans and questionnaires showed that people who seek high levels of stimulation or excitement – for example people predisposed to substance abuse or high adventure pursuits, or aggressive business practices, or even gambling – had reduced thickness in areas of the brain involved in decision-making and self-control. They were also less averse to risk. Two specific regions – the anterior cingulate and middle frontal gyrus – the areas that regulate emotions and behaviour – showed the biggest differences.
The most pronounced of these were found where differences coincided with a participant’s tendency to act on impulse. The relationship was just as strong in people who did not use drugs as those who did, showing that it is the thinner brain structure that affects behaviour and not the behaviour that affects the structure.
Other research has already confirmed that drug use can affect brain anatomy, and that genetics plays a part in thrill-seeking and impulsive behaviour.
The significance of individual variability in brain anatomy is still a matter of debate, but the findings allow for a better understanding of how variation in brain anatomy might affect temperamental characteristics and heath related behaviours and the possibility of predicting the likelihood of substance abuse in individuals, as well as risk-taking and impulsive behaviour.
The results of that study were published in the April 2017 edition of the Journal of Neuroscience.