Stress, tiredness, and general cognitive strain make it much harder for us to ignore signals in the environment for something rewarding -- such as bright neon signs for fast food joints.
We all have impulses we'd like to have a better handle on. Some of you might be trying to diet, quit smoking, or kick some other habit; good luck. New research says that tiredness, stress, or any other drain on your mental resources can make it harder for you to resist tempting cues and thus make good on your decision. The team says that trying to hold information in our memory also produces this effect, the first time this link has been demonstrated.
"We knew already that participants find it hard to ignore cues that signal a large reward," says study lead Dr. Poppy Watson at UNSW.
"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 refer to the cognitive processes that allow us to pay attention, organize our life, focus, or regulate our emotions as 'executive control'. It wasn't yet clear whether our ability or inability to ignore reward cues (i.e. temptation) was related to executive control or a separate ability, but the present research suggests that the former is true: executive control processes are employed to keep us from distractions or temptations. However, the findings also show that these resources are limited.
"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," says Dr. Watson.
For the study, the team had participants look at a screen on which various shapes -- including a colorful circle -- were being displayed. Their task was to locate and look at a diamond shape on the screen, and if successful, they'd be given money. However, if they looked at the colored circle -- which played the part of the distraction/temptation -- they wouldn't receive money. To make things even harder, participants were told that the presence of a blue circle on-screen meant that they'd be paid more if they successfully completed the diamond task than if an orange circle was shown.
The team tracked where each participant was looking using eye-tracking technology. The team ran a low-memory load and a high-memory load version of the experiment. In the high-memory load version, the participants were also asked to memorize a sequence of numbers while performing the larger task. This set-up was used to further draw from the participants' cognitive resources and to see how this impacted their ability to perform 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 says.
"Crucially, the circles became harder to ignore when people were asked to also memorize numbers: under high memory load, participants looked at the coloured circle associated with the high reward around 50% of the time, even though this was entirely counterproductive."
The findings suggest that people need access to either full or at least a sizeable chunk of their cognitive control processes to successfully block distractions or temptations from the environment. This mechanism, ironically, seems to make it harder to ignore cues regarding habits or behaviors you want to change -- because you're paying attention to changing them specifically. This might also explain why people find it harder to focus on dieting or beating an addiction if they are under a lot of stress.
"There's this strong known link between where your attention is and what you eventually do, so if you find it hard to focus your attention away from reward cues, it's even harder to act accordingly," says Dr. Watson. "Constant worrying or stress is the equivalent to the high-memory load scenario of our experiment, impacting on people's ability to use their executive control resources in a way that's helping them manage unwanted cues in the environment."
The team wants to see if executive control can be strengthened and if that can be used in the context of drug rehabilitation.
The paper "Capture and Control: Working Memory Modulates Attentional Capture by Reward-Related Stimuli" has been published in the journal Psychological Science.