We are what we repeatedly do
We’re publishing the shortlisted entries to the 2012 Wellcome Trust Science Writing Prize. Here, Dave MacLeod on what our habits tell us about ourselves.
Imagine how difficult life would be if you couldn’t develop habits. If every time you made a cup of tea, tied your shoes or left the house you had to consciously focus on every action. Life wouldn’t just be difficult; it would be impossible. Fortunately, much of what we do every day can be described as habitual behaviour. Our habits define us, and whilst they might not all be desirable, habits have a clear evolutionary advantage.
The brain is constantly looking for ways to save energy. It uses more than any other organ in the body and habits allow it to work less and use less. When routine behaviour becomes habitual, its focus is freed up for other tasks. This was an evolutionary advantage for our ancestors, when a loss of attention at the wrong moment was the difference between catching dinner and becoming it. The humans who were best at forming habits became us.
When habits form, neural pathways in the brain associated with sequences of activity are integrated into a whole, in a process known in psychology as “chunking”. Studies have also shown that as habits develop there is a downward shift in brainwave frequency from high-frequency gamma to low-frequency beta waves. In the brain, gamma waves are generally associated with highly attentive states, whereas beta waves are associated with a lack of movement.
A specific part of the brain associated with habit formation has been also identified: a protein known as an NMDA receptor, found on dopamine neurons. In recent experiments, researchers bred mutant mice missing the receptor, which were incapable of developing habits. When presented with a food-giving lever to push, the mutant mice pushed it and ate their fill, but showed no intention of pushing it once they were satisfied. Normal mice on the other hand kept on pushing the lever even after they were full, indicating that they had a habit that the mutant mice without NMDA failed to develop.
These receptors help to generate an electrical response when an animal is repeatedly exposed to a rewarding cue. This is what scientists believe turns ordinary learning into automatic behaviour. With no receptor present, there is no electrical response, and thus no habit forms.
The researchers also did the opposite experiment, breeding another mouse with an excess of the NMDA receptor. This mouse was able to learn faster, recognising objects better and solving mazes quicker than a normal mouse. Other experiments have shown further that a significant part of the NMDA receptor is higher in rats at birth and declines as they age – which may be one reason why younger brains are able to more easily learn new routines and absorb new information quicker.
However, our success as habit-forming creatures is a double-edged sword. We can habitually exercise, or consistently watch too much television. Most drivers unconsciously check their mirrors and put on their seatbelt before setting off while others habitually drive too fast. The flipside of our ease of forming habits is our difficulty in removing them, but by better understanding the nature of our habits we might perhaps more easily break them.
Studies have suggested that habit-breaking strategies that work by goal-setting and internal motivation are ineffective, and more successful strategies target environmental triggers. Researchers have shown that our environment rather than our willpower is often responsible for triggering our habits. For instance, the way we consume food is strongly influenced by our kitchens, tables and plates – the environment in which we eat has an effect on what kind of food we eat and how much, so reengineering our eating areas may have a more positive impact on our health than just relying on willpower alone.
Habit change strategies are also most effective when people are naturally changing their environment. In one study, participants who had recently moved were more likely to change their mode of transport than others who had not moved. This explains why, in order to increase public transport use, bus companies often supply free passes and route information to new residents in an area, since they are yet to establish relevant habits.
Advice to “know thyself” has been around a long time. By better understanding our habits we understand ourselves.
- Wang LP, Li F, Wang D, Xie K, Wang D, Shen X, & Tsien JZ (2011). NMDA receptors in dopaminergic neurons are crucial for habit learning. Neuron, 72 (6), 1055-66 PMID: 22196339
- Chang LR, Liu JP, Zhang N, Wang YJ, Gao XL, & Wu Y (2009). Different expression of NR2B and PSD-95 in rat hippocampal subregions during postnatal development. Microscopy research and technique, 72 (7), 517-24 PMID: 19306263
- Sobal, J., & Wansink, B. (2007). Kitchenscapes, Tablescapes, Platescapes, and Foodscapes: Influences of Microscale Built Environments on Food Intake Environment and Behavior, 39 (1), 124-142 DOI: 10.1177/0013916506295574
- Neal, D., Wood, W., Labrecque, J., & Lally, P. (2012). How do habits guide behavior? Perceived and actual triggers of habits in daily life Journal of Experimental Social Psychology, 48 (2), 492-498 DOI: 10.1016/j.jesp.2011.10.011
- Wood, W., & Neal, D. (2007). A new look at habits and the habit-goal interface. Psychological Review, 114 (4), 843-863 DOI: 10.1037/0033-295X.114.4.843
- Tang YP, Shimizu E, Dube GR, Rampon C, Kerchner GA, Zhuo M, Liu G, & Tsien JZ (1999). Genetic enhancement of learning and memory in mice. Nature, 401 (6748), 63-9 PMID: 10485705
This is an edited version of Dave’s original essay. Views expressed are the author’s own.
Over the next couple of months, we’re publishing the shortlisted essays from the 2012 competition. Read all, and the 2011 essays, in our archive.