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12 Jul 2019

A University of New South Wales psychology experiment has shown why it can be so hard to direct attention away from cues that might lead to excessive alcohol drinking and eating of unhealthy food.

When someone is stressed, tired or otherwise straining their brain power, ubiquitous neon lights and advertisements can be harder to ignore, especially when they might be signalling something rewarding.

Psychologists at UNSW Sydney conducted an experiment that found exactly that. The research has been published in Psychological Science.

The experiment showed for the first time that ignoring such cues becomes harder as soon as a task has to be performed while also holding other information in one’s memory.

“We knew already that participants find it hard to ignore cues that signal a large reward,” said study lead Dr Poppy Watson.

“We have a set of control resources that are guiding us and helping us suppress these unwanted signals of reward. But when those resources are taxed, these become more and more difficult to ignore.”

Researchers did not know before whether a general inability to ignore reward cues was something people have no control over or whether executive control processes are used to constantly work against distractions.

It has now become clear that the latter is the case, but executive is a limited resource.

Executive control is a term for all cognitive processes that allow us to pay attention, organise, focus, and regulate our emotions.

“Now that we have evidence that executive control processes are playing an important role in suppressing attention towards unwanted signals of reward, we can begin to look at the possibility of strengthening executive control as a possible treatment avenue for situations like addiction,” Dr Watson said.

In the experiment, participants looked at a screen that contained various shapes including a colourful circle. They were told they could earn money if they successfully located and looked at the diamond shape, but that if they looked at the coloured circle – the distractor – they would not receive the money.

They were also told that the presence of a blue circle meant they would gain a higher amount of money (if they completed the diamond task) than the presence of an orange circle. The scientists then used eye tracking to measure where on the screen participants were looking.  

To manipulate the ability of participants to control their attention resources, they had to do the task under conditions of both high memory load and low memory load.

In the high-memory load version of the experiment, participants were asked to memorise a sequence of numbers in addition to locating the diamond, meaning they had fewer attention resources available to focus on the diamond task.

“Study participants found it really difficult to stop themselves from looking at cues that represented the level of reward – the coloured circles – even though they were paid to try and ignore them,” Dr Watson said.

“Crucially, the circles became harder to ignore when people were asked to also memorise numbers. Under high memory load, participants looked at the coloured circle associated with the high reward around 50 per cent of the time, even though this was entirely counterproductive.”

The findings demonstrate that people need full access to cognitive control processes to try and suppress unwanted signals of reward in the environment.

This is especially relevant for circumstances where people are trying to ignore cues and improve their behaviour, for example consuming less alcohol or fast food.

The researchers now want to look at how executive control can be strengthened – and if that presents an opportunity for situations like drug rehab. 

Published: 12 Jul 2019