Imagine you're taking a test--just for fun--to see how fast you can add numbers and alphabetize letters. Would it help you complete the test faster if you had a warning before each item indicating whether you'd be adding or alphabetizing?
Now imagine you're taking the same test--only this time the test will be used to determine whether you qualify for a promotion at work. In this, more stressful situation, do you think the warnings would help? Would you change your strategy on the test?
There is considerable evidence that cognitive performance changes when we are under stress. For example, women tend to perform worse on math tests than men when they are specifically told the test is designed to detect gender differences. Asian women perform worse on math tests when the opposite occurs, and the stereotype that Asians are better than others at math is invoked prior to the test.
Other studies have explored more generic reactions to stress and found that in many cases test-takers use different problem-solving strategies when they are under more stress: typically the strategy used under stress is one which utilizes fewer cognitive resources. Apparently simply being in a stressful state consumes some cognitive resources, so the adaptation is to use a less demanding strategy -- even if that strategy is slower or less effective.
But what about when a test involves switching between different tasks? A team led by Marco Steinhauser believes it has developed the first study to explore how stress affects the way people switch between tasks.
Their study involved two very simple tasks: determining whether a number was odd or even, and deciding whether a letter was a consonant or a vowel. These tasks were randomly mixed, so that sometimes a number task would be followed by another number task, and other times the assignment would switch to a letter task. In every case, participants were warned with a cue indicating which type of task was coming up -- a circle indicated a number task, and a square indicated a letter task. But the time between the appearance of the cue and the task varied.
Most importantly, some participants were under stress, while others were not. How was stress induced? Before beginning the task, the low-stress users took a very easy test, which involved selecting similar or different words, completing a number series, and so on. They were told this test was used for calibrating the study and their individual results would not be analyzed.
The high-stress users took a much more difficult version of the test, including some items that were not solvable. In addition, they were told this was an IQ test, and that they could compare their results in the ensuing study with the results from the local student population.
Here's how the results compared:
Both high- low-stress individuals improved performance (had faster reaction times) when the cue appeared sooner, giving them a longer time to prepare for each task. The results for both high- and low-stress individuals were similar when the task shifted between numbers and letters. However, when the same task was repeated, the groups responded very differently. As you might expect, both groups were faster to respond when the same task was repeated, but for low-stress individuals, the pattern of their results was significantly different when the task repeated compared to when it shifted, while for the high-stress group, it was not.
Steinhauser et al. argue that this means that the high-stress individuals are using the same strategy for responding to the cues, whether the task changes or not. The cost of a task shift was the same for both short and long cues for high-stress individuals, but not for low-stress individuals. This means that high-stress individuals must be using a different, and arguably a simpler method for dealing with the changing (or not-changing) tasks.
Interestingly, average performance was not different between the two groups on this task, but this isn't to say that in certain circumstances high stress might impair performance when people are frequently asked to switch between tasks (as indeed it does on the achievement tests we mention above). Another possibility, mentioned by the study authors, is that the brain automatically selects the strategy which uses the available resources most effectively.
However, this study about choking under pressure seems to bely that notion.
Steinhauser, M. Maier, M., & Hübner, R. (2007). Cognitive control under stress: How stress affects strategies of task-set reconfiguration. Psychological Science, 18(6), 540-545.
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As you might expect, both groups were faster to respond when the same task was repeated, but for low-stress individuals, the pattern of their results was significantly different when the task repeated compared to when it shifted, while for the high-stress group, it was not.
This is another case where looking at the graph and reading the above give two very different impressions -- error bars probably aren't enough; are you saying that an ANOVA analysis says that the two lines on the right aren't different?!
Are you saying that an ANOVA analysis says that the two lines on the right aren't different?!
No, they are different -- but they are different from each other in a different way compared to the two lines on the left, suggesting that people under stress use a different strategy to handle a task that might switch at a given moment.