By Emma Young
How do children learn to fear things that aren’t obviously scary, but that do pose a threat — to learn, say, that touching the base of a lit barbecue is a very bad idea, so should never be done? A parent might explain that it’s dangerously hot. But as a new paper published in Scientific Reports explores in detail, we also benefit from another more direct, wordless method of learning about threats. Or rather, we may typically benefit from it — but, Marie-France Marin at the University of Quebec and her colleagues argue, it might also help to explain how anxiety disorders are transmitted down through generations.
Marin and her team set out to explore so-called vicarious learning between 83 child-parent pairs. This entails learning by observing another person’s reactions to objects or events. So if a child sees a parent flinch after touching a lit barbecue, despite never having experienced that pain themselves, they can learn never to do it. The team wanted to look, though, at how this type of learning might manifest at the physiological level. Fear and anxiety are characterised by an increase in physiological arousal — a raised heart rate, blood pressure, sweating, and so on — all of which gear up the individual for fight or flight.
For this study, the team focused on skin conductance as an indicator of general physiological arousal. Each parent was fitted with sensors to measure this, as well as electrodes that were set to deliver an “annoying” rather than painful shock. The parent was then videotaped while they watched, via a monitor, a lamp that flashed various colours. When one particular colour flashed (either red or blue), five times out of eight the parent received a shock. When another colour (yellow) was flashed, a shock was never administered. They learned, then, to associate one particular colour with receiving a shock, and one with being safe.
Each child was shown the video of their own parent’s reactions and also a video of a stranger of the same sex as their parent undergoing the same procedure. (The shocks were associated with a different colour for the stranger and parent: if the parent was shocked when a red light flashed, for instance, the stranger was shocked when the blue light flashed). The child was then put in the same experimental set-up as the adults, except that they were never actually shocked.
The skin conductance data showed that children reacted with alarm to the red and blue lights, but not the yellow light. They had, then, learned to fear the colours associated with a shock to either their parent or a stranger. This suggests that children can learn from any adult, at least to some extent. But the team also found that children who showed greater “physiological synchrony” with their parent — so the child’s shifts in skin conductance levels more closely mirrored those of its parent during the course of the experiment — had stronger alarm reactions when they saw their parent being shocked. This suggests that children who are better “tuned” into their parents’ emotional states vicariously learn fear faster. (Exactly what underpins “better tuning” is not clear, but the quality of the parent/child relationship and the expressiveness of the adult will play a role.)
In the real world, the team notes, “parents transmit a lot of information to their children through their body language and their reactions to environmental stimuli”. If a parent responds appropriately to objects or events in the environment — signalling an appropriate level of fear or pain in response to something that is genuinely dangerous, but not to non-threats — then the child will clearly benefit. However, if the parent has a fear or anxiety disorder and becomes afraid or anxious when there is no genuine threat, their child could then learn these inappropriate responses.
Anxiety disorders often emerge in childhood, with a median age of onset of 11. “Given that [the] risk for anxiety and fear-based disorders is transmitted within families, it is essential to study how children form fearful associations when learning from their parent’s experience,” the researchers stress. Clearly, there’s more work to be done to understand these processes, but this research suggests that the level of physiological synchrony between a child and parent has an influence. This is an area that the team now plans to explore further, in the hope of finding new approaches to preventing or treating anxiety disorders in children.