It’s well known that people differ from one another in their cognitive functioning. Some people consistently have a better memory, learn faster, reason more accurately, and can understand things more quickly than others.
Our understanding of fluctuations in cognitive functioning within a person, over time, are much less well understood.
In a new paper, rising superstar Sophie von Stumm adds to this growing literature on within-person differences by looking at patterns of change in both cognitive functioning and mood within people, across time.
First, Sophie measured cognitive ability on five consecutive days, including short-term memory, processing speed and working memory. Second, she had participants complete daily measures of positive and negative emotions.
What did she find?
As you can see here, there were substantial fluctuations both within people and between people in cognitive functioning across the five days:
However, most of the differences really were evident between people:
Even so, within-person differences accounted for twice as much of variation in positive and negative emotions compared to the tests of cognitive ability. What’s more, between-person differences in affect were less consistent than cognitive functioning across the five days. It seems that cognitive functioning is simply more stable than mood. Also, the experience of positive and negative emotions were mostly independent of each other.
Perhaps most interestingly, at the within-person level of analysis, there was no significant correlation between daily changes in affect and daily changes in cognitive functioning.*
These findings are a bit perplexing. After all, there is prior evidence suggesting that extreme stress and anxiety can impact cognitive functioning. The prior research on this topic, however, has focused mainly on patterns of correlations between people, not within people. What’s more, this study suggests that our normal everyday fluctuations in emotional functioning do not significantly impact the consistency of our cognitive functioning.
This study adds to a growing and important literature that is part of the new and important “person-specific paradigm“. Between-person differences can reveal very different patterns of associations than within-person differences, and this is sure to have deep implications for a wide range of personality and motivational processes.
* With the exception of a significant association between positive emotions and processing speed. According to van Stumm, “Put bluntly, the results suggest that people who have a general tendency to be more enthusiastic and alert have faster brains but additional research will be needed to substantiate this observation.”