3 . 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.

7 . On March 7, 1907, the English statistician Francis Galton published a paper which illustrated what has come to be known as the “wisdom of crowds” effect. The experiment of estimation he conducted showed that in some cases, the average of a large number of independent estimates could be quite accurate.

This effect capitalizes on the fact that when people make errors, those errors aren’t always the same. Some people will tend to overestimate, and some to underestimate. When enough of these errors are averaged together, they cancel each other out, resulting in a more accurate estimate. If people are similar and tend to make the same errors, then their errors won’t cancel each other out. In more technical terms, the wisdom of crowds requires that people’s estimates be independent. If for whatever reasons, people’s errors become correlated or dependent, the accuracy of the estimate will go down.

But a new study led by Joaquin Navajas offered an interesting twist (转折) on this classic phenomenon. The key finding of the study was that when crowds were further divided into smaller groups that were allowed to have a discussion, the averages from these groups were more accurate than those from an equal number of independent individuals. For instance, the average obtained from the estimates of four discussion groups of five was significantly more accurate than the average obtained from 20 independent individuals.

In a follow-up study with 100 university students, the researchers tried to get a better sense of what the group members actually did in their discussion. Did they tend to go with those most confident about their estimates? Did they follow those least willing to change their minds? This happened some of the time, but it wasn’t the dominant response. Most frequently, the groups reported that they “shared arguments and reasoned together”. Somehow, these arguments and reasoning resulted in a global reduction in error. Although the studies led by Navajas have limitations and many questions remain, the potential implications for group discussion and decision-making are enormous.