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Every decision we make is arrived at through hugely complex neurological processing. Although it feels as though you have a choice, the action that you ‘decide’ to take is entirely directed by automatic neural activity. Brain imaging studies show that a person’s action can be predicted by their brain activity up to 10 seconds before they themselves become aware they are going to act. Multiple neuroscientific studies show that even those important decisions that feel worked out are just as automatic as knee-jerk reactions (膝跳反应) (although more complex).

Decision-making starts with the amygdala: a set of two almond-shaped nuclei (杏仁状核) buried deep within the brain, which generate emotion. The amygdala registers the information streaming in through our senses and responds to it in less than a second, sending signals throughout the brain. These produce an urge to run, fight, freeze or grab, according to how the amygdala values various stimuli.

Before we act on the amygdala’s signals, however, the information is usually processed by other brain areas, including some that produce conscious thoughts and emotions. Areas concerned with recognition work out what’s going on, those concerned with memory compare it with previous experiences, and those concerned with reasoning, judging and planning get to work on constructing various action plans. The best plan—if we are lucky—is then selected and carried out. If any of this process goes wrong, we are likely to hesitate, or do something silly.

The various stages of decision-making are marked by different types of brain activity. Fast (gamma)waves, with frequencies of 25 to 100 Hz, produce a keen awareness of the multiple factors that need to be taken into account to arrive at a decision. If you are trying to choose a sandwich, for instance, gamma waves generated in various cells within the ‘taste’ area of the brain bring to mind and compare the taste of ham, hummus, wholemeal, sourdough, and so on. Although it may seem useful to be aware of the full range of choice, too much information makes decision-making more difficult, so irrelevant factors get dismissed quickly and unconsciously.

After this comparison stage, the brain switches to slow-wave activity (12 to 30 Hz). This extinguishes most of the gamma activity, leaving just a single ‘hotspot’ of gamma waves which marks the chosen option.

Although there is no ‘you’ outside your brain to direct what it’s doing, you can help it to make good decisions by placing yourself in a situation which is likely to make the process run more smoothly. Doing something that is physically or mentally stimulating before making a decision will help your brain produce the initial gamma waves that generate awareness of the competing options. Getting over-excited, on the other hand, will prevent the switch to the slow brainwaves, making it much harder to single out a choice.