Tag Archives: decision

Our brains tend to judge whole experiences by how they ended, which can lead to poor decisions in the future

How we remember our enjoyment of past experiences isn’t always reliable, according to new research. The study explains that humans tend to remember those that end well as more enjoyable and those that end poorly as less enjoyable, even if the two were equally pleasant.

Image credits Dariusz Sankowski.

The findings showcase why we shouldn’t blindly trust our past experiences to inform decisions in the present. If we keep in mind that the last bits of any experience have a disproportionately high effect on our memory of it, we’ll be able to make better choices, the authors hope.

Happy ending?

“When you’re deciding where to go for dinner, for example, you think about where you’ve had a good meal in the past. But your memory of whether that meal was good isn’t always reliable — our brain values the final few moments of the experience more highly than the rest of it,” said Dr Martin Vestergaard, a researcher in the University of Cambridge’s Department of Physiology, Development, and Neuroscience, who led the study.

This preference seems to come built-in in humans, Vestergaard explains. Its effect seems to dampen over time — our memory of something we did a long time ago will factor less into our decision-making than a more recent one.

The process has its roots in two different brain areas which are activated whenever we try to make a decision based on experiences in our memory. However, they also compete with each other while doing so, making us either overvalue experiences that started badly and end well or undervalue experiences that started well and end poorly.

A part of the brain known as the amygdala then uses our memories to work to determine the ‘objective value’ of an experience (such as how tasty a meal was). The other, called the anterior insula, makes older memories progressively less important in our decision-making process. This holds true even among our most recent memories — the further back in time it is, the less it factors into our decisions.

For the study, the team enlisted 27 healthy male volunteers and asked them to estimate which one of two pots of coins on a screen had the greatest total value (these pots were shown one at a time, not side-by-side). They were also shown how coins of varying sizes fell from the pots in quick succession. A functional magnetic resonance imaging (fMRI) machine was used to see what the participants’ brains were doing during the experiment. The task was repeated several times with different sequences of coins.

Participants routinely chose the wrong pot when the coins shown decreased in size by the end of the sequence, the team explains. This suggests that their brains were using this more modest end as a cue to estimate a lower total value. Although the intensity of this effect seemed to vary between participants, only a handful were able to completely bypass it and make rational estimations, according to the authors.

Such results suggest that our current theoretical models on decision-making — chiefly that sub-obtimal decision-making is handled by the amygdala, with higher brain areas handling more complex decisions — is correct. But on a personal level, they showcase to each of us how the final moments of an experience influence our perception of the whole, especially when judging from memory.

“Our attraction to the quality of the final moment of an experience is exploited by politicians seeking re-election; they will always try to appear strong and successful towards the end of their time in office,” said Vestergaard.

“If you fall for this trick, and disregard historical incompetence and failure, then you might end up re-electing an unfit politician. Sometimes it’s worth taking the time to stop and think. Taking a more analytical approach to complement your intuitive judgement can help ensure you’re making a rational decision.”

The paper “Retrospective valuation of experienced outcome encoded in distinct reward representations in the anterior insula andamygdala” has been published in the Journal of Neuroscience.

Excitement, not profit, drives young burglars to crime

Young burglars are driven more by excitement than anything else when committing their first crimes, a new study finds.

Image via Pixabay.

The authors wanted to highlight the role emotions, namely positive emotions such as excitement, play in the initial decision to commit a crime. This initial decision is very important, they explain, as the experience they gain until the rush fades off makes it more likely that individuals will turn to habitual offending.

Do it for the vine

“It’s important to understand under what circumstances young people make that initial decision to commit a crime, so we can think about intervention,” says Dr. Claire Nee, Reader in Forensic Psychology, who led the study.

“The role of emotion in driving the desire to commit crime is a much neglected area and our research indicates it could be key to stopping it in its tracks. The excitement drives the initial spate of offending, but skill and financial reward quickly take over resulting in habitual offending.”

The team worked with a group of young burglars (average age 20) and an older, more experienced group of residential burglars (average age 39). The participants were asked to carry out a virtual burglary, a simulated environment in which they had to pick and break into a property. The team asked them to ‘think aloud’ during the exercise, and later interviewed each participant on his decision-making process and actions. They were also asked about their experiences in the days or hours before their real-life burglary to see what process led them to commit the crime.

The team found that nobody was actually intent on being a burglar; the participants simply drifted to the ‘profession’, they didn’t rush headlong for it. Yet, offending was often considered an integral and almost inevitable part of participants’ lifestyles. One young burglar said that “where [he’s] from, that’s what it’s like, it’s crime, like, that’s the norm.” An older burglar also recounted that he “was just born on the streets” and “that’s what people do [on the streets]”.

“What really struck me about the research is how young offenders can’t identify a clear initial decision to commit a burglary — it’s just part of the ‘flow’ of what they’re doing with their adolescent comrades,” says Dr. Nee.

The authors say that their results suggest that the initial burglaries are linked with the desire for excitement; it’s a thrill the first couple of times, they explain, but this fades away with repeated offenses. After this point, the participants were more motivated by the prospect of making quick, easy money; one participant recalls “thinking, wow, is this what 10 minutes of work is?” after a burglary.

Better knowing how people turn to crime and what motivates them at various stages can help us design better intervention procedures to prevent or cut short a career in crime.

The paper “Expertise, Emotion and Specialization in the Development of Persistent Burglary” has been published in The British Journal of Criminology.

Doors choices.

Our brains don’t like having too many options to pick from because they’re lazy

Having too many choices to pick from can, ironically, make it impossible for us to decide. New research is looking into the neurological origins of this effect, known as choice overload.

Doors choices.

Image credits Arek Socha.

We all like to have options to pick from. Be it in the grocery food aisles, at the department store when looking for jeans, or at the pub, we enjoy browsing for that perfect item. The reality on the ground doesn’t seem to match our expectations, however. Past research has shown that, when faced with too large a number of similar options, our brain struggles to make a decision.

Too much of a good thing

A previous study conducted in California (Iyengar & Lepper, 2000, PRID) pitted customers at a grocery store against a table of jam samples — with quite interesting results. The team offered samples of either 6 or 24 kinds of jam at a time. While shoppers were much more likely to stop and try the jams when more varieties were made available, they were way less likely to actually purchase a jam. In contrast, when only six samples were put on display, shoppers were less likely to stop at the table — but 10 times more likely to purchase a jam than the first group.

We don’t really know why this happens. We know it can cause some real problems by impacting our decision-making ability in important areas — what retirement fund to invest in, for example, or what college to attend. In a bid to better understand the mechanisms that underpin choice overload, researchers at Caltech looked at the human brain as it was struggling to make a choice.

The team recruited volunteers, placed them in an fMRI (functional magnetic resonance imaging) scanner, and presented them with 6, 12, or 24 pictures of scenic landscapes. Participants were asked to pick the one they would like printed for them on a piece of merchandise (such as a coffee mug).  As a control, the volunteers were later asked to look through the images again, but without having to make a decision — instead, it was made randomly by a computer.

The team led by Colin Camerer, Caltech’s Robert Kirby Professor of Behavioral Economics, reports recording brain activity in two brain areas while the participants were making their choices. These were the anterior cingulate cortex (ACC), where the potential costs and benefits of decisions are weighed, and the striatum, a part of the brain responsible for determining value.

Activity peaked for subjects who had 12 options to pick from, the team reports, and was lowest for those given either 6 or 24 choices. Carmer believes this pattern of activity likely comes down to the interaction between the striatum and ACC, as these two areas communicate to weigh potential rewards (getting a mug with a picture they like printed on) against the effort required to decide which picture they like best.

‘That sounds like a lot of work’

When more options come into play, potential rewards increase — but after a point, they level off due to diminishing returns. In other words, even if your brain thinks it would be neat-o to have a cool picture on its shiny new mug, if there are too many pictures to look at and evaluate, it’s simply not worth the hassle. Our brains are looking to hit a sweet spot where the effort isn’t too great and the reward meaningful enough to bother making a decision.

“The idea is that the best out of 12 is probably rather good, while the jump to the best out of 24 is not a big improvement,” Camerer says.

This view is supported by the results of the control phase: the specific pattern of activation was not seen when participants just browsed the images because there was no potential for reward — so there was no point in seriously assessing the images.

Camerer notes that 12 isn’t this ‘sweet spot’ — the number is just an artifact of how the team designed their experiment. The ideal number of options for an average person, he estimates, is probably somewhere between 8 and 15 — depending on the perceived reward, the difficulty of evaluating the options, and the person’s individual characteristics.

Why, then, are shops stocked with ample products, giving us such a wealth of options to pick from? The team says it’s likely because we tend to feel like we have more control over our lives when we have more options to pick from, even if that means having a harder time choosing between them.

“Essentially, our eyes are bigger than our stomachs,” Carmer says. “When we think about how many choices we want, we may not be mentally representing the frustrations of making the decision.”

The team says that in the future, they’ll focus their research on attempting to quantify the mental costs of making a decision.

The paper “Choice overload reduces neural signatures of choice set value in dorsal striatum and anterior cingulate cortex” has been published in the journal Nature Human Behaviour.

Alan Turing Enigma

Decisions are reached in the brain by the same method used to crack the Nazi Enigma code

The highlight of the award winning film, “The Imitation Game”, is when Alan Turing and colleagues devise an ingenious statistical method that eventually helped decipher the Nazis’ Enigma code. This breakthrough allowed Allied intelligence to read previously unavailable German military positions and actions, vastly shortening World War II. Interestingly, a team of neuroscientists at Columbia University found that more or less the same statistical method applied by Turing and co. is used by the brain to make any kind of decision, be it going left instead of right in an intersection or placing a higher bet during a high raise power game instead of folding.

Enigmatic Brain

Alan Turing Enigma

Image: BBC

German military messages enciphered on the Enigma machine were first broken by the Polish Cipher Bureau, beginning in December 1932. Later versions, however, were of increased complexity and by the time the war broke out, cracking Enigma proved to be a cumbersome riddle. But while the machine was great at encrypting messages, its operators were not necessarily so. The British intelligence had their breakthrough after they systematically exploited German Enigma operator flaws. For instance, the Nazis had the bad habit of broadcasting messages which began with the same text, depending on the situation, like ‘The weather report for today is’. Knowing this, they could take the coded text and know how the first characters would decode. With the knowledge that no letter encrypted could be the same letter decrypted, the number of combinations possible was massively reduced.

Even so, the volume of work needed to break the codes by brute force alone was immense. It simply took too much time. Time they didn’t have. Eventually, Turing employed several statistical techniques to crack Enigma like Banburismus, which is a highly intensive, Bayesian system that allowed Turing and colleagues to guess a stretch of letters in an Enigma message, measure their belief in the validity of these guesses – using Bayesian methods to assess the probabilities – and add more clues as they arrived. Basically, this statistical test decided if two messages were similar enough then decide if these formed a pair, or not.

The animated GIF below gives you an idea of how the system worked. Corresponding pairs of letters from the two messages are aligned one above the other. At first glance, it all looks like gibberish, but the British WWII researchers knew they could preserve the matching probabilities of the original messages, as some letters are more common than others. So in any two messages, any matching pairs of letter were given a positive value and unmatched ones a negative value. When a positive threshold was researched, the code was deemed broken.

tuiring test

Michael Shadlen, MD, PhD, professor of neuroscience at Columbia draws an interesting parallel between the process employed in solving Enigma and the way the brain fires neurons to reach a decision. His team recorded the activity of neurons in the brains of two monkeys as they made a simple decision: choose between two spots for a reward. The decision had to be made fast, since the symbols – right and decoys – appeared in short 250 millisecond-long sequences. To reach the correct decision, the monkeys had to weigh different clues encoded in the symbols that flashed onto the screen. Some of the eight symbols were unreliable clues about the reward’s location; others were more dependable.

Meanwhile, researchers studied how the monkeys’ brains came to a decision by studying the neural activity. If a symbol was tied to a reward it would be assigned a positive value. Conversely a symbol was assigned a negative value if it wasn’t associated to a reward. Together, these amounted to the accumulated evidence range which was represented in the neuron’s firing rate. The more reliable the symbols were, the larger the impact on the firing rate. So, just like in Turing’s test once a positive – or negative, for that matter – threshold was reached, the monkey would come to a decision. The findings appeared in the journal Neuron.

Shadlen believes it’s sensible to claim the human brain works much in the same way to come to a decision.

“It’s the basis of a very basic kind of rationality,” he says.

“They’re decisions like, ‘I’m going to pick up a book,’ or ‘I’m going to walk toward the left of the coffee table, not the right,’” Dr. Shadlen adds.

“We make lots of these decisions every day, and it turns out, we’re making them by using the laws of probability in a way that statisticians think is optimal.”

I think we all knew all along there’s an ‘enigma’ tucked inside our minds somewhere. Now we know you can break it – you just need the right code.

How cockroaches make democratic group decisions

For cockroaches, it seems, collaboration comes naturally: when 50 cockroaches are presented with 3 shelters which can only host 40 (each), they’ll split into two groups, leaving the third shelter empty. Basically, they find a way to split themselves equally, in a democratic fashion.

In cockroach groups, there are no members higher than others – everybody is equal, apparently. Thus, group decision making is simplified, leading to patterns which can be understood and studied. What makes it even more interesting is that cockroaches don’t make sounds, so they must therefore communicate without vocalizing.

“Cockroaches use chemical and tactile communication with each other,” says Dr José Halloy, who co-authored the research in the current Proceedings of the National Academy of Sciences. “They can also use vision,” says Halloy, a scientist in the Department of Social Ecology at the Free University of Brussels in Belgium. “When they encounter each other they recognise if they belong to the same colony thanks to their antennae that are ‘nooses’, that is, sophisticated olfactory organs that are very sensitive,” he says.

Halloy wanted to see how the cockroaches would behave when faced with a decision. He placed the insects in a dish that contained three shelters. Initially, the shelters could only host 40 insects each, so the 50 bugs decided to split equally – 25 into one, 25 into the other, leaving the third one empty. However, when the shelters were larger than 50, they all moved into just one shelter, showing that they make rational, democratic group decisions.

“Cockroaches are gregarious insects [that] benefit from living in groups. It increases their reproductive opportunities, [promotes] sharing of resources like shelter or food, prevents desiccation by aggregating more in dry environments, etc,” he says.”So what we show is that these behavioural models allow them to optimise group size.”

The way they behave is so basic and rational, that it can be quite predictable to model. Researchers hope to draw insights for other insects as well – and not only insects.

“It looks both at the mechanisms underlying decision-making by animals and how those mechanisms produce a distribution of animals amongst resource sites that optimizes their individual fitness,” says Dr David Sumpter, a University of Oxford zoologist.”Much previous research has concentrated on either mechanisms or optimality at the expense of the other.”

The study documenting this behavior was published in PNAS in 2006.