By Christian Jarrett

In the ongoing, complex debates about the extent and meaning of psychological differences between the sexes, mental rotation ability is usually quoted as one of the most robust examples of where a difference can be found. This is the ability to rotate objects in your mind’s eye, and while there is a lot of overlap between men’s and women’s performance, there is plenty of evidence that men, on average, are better at this than women. Can we take this to reflect a genuine, specific difference in average cognitive ability between the sexes?

Not necessarily. A new, small study in Psychological Research reminds us why this field of science is so difficult to interpret. The findings suggest that the mental rotation ability of women who habitually suppress the public display of their emotions is equal to that of men. In other words, sex differences in mental rotation ability may reflect an emotional difference between the sexes – emotional suppression is known to be more common in men than women – rather than a cognitive difference.

Anne-Katharina Faltung and Markus Kiefer asked 28 men and 28 women to fill out some surveys about their emotional lives, including their proneness to angry outbursts and their tendency to suppress public displays of emotion (one example item was “I keep my emotions to myself”).

Then the participants completed 48 trials of a classic mental rotation task, which involved judging within four-seconds per trial whether or not a three-dimensional shape on the left of the computer screen was the same as the one on the right, just rotated to a different orientation. The trials got harder as the task went on, and emoji-type symbols and spoken feedback (such as “Oh dear, you made a mistake”) informed the participants whether they’d got each trial right or not.

Overall, the men outperformed the women in terms of making fewer total errors, and in being less likely to follow up one error with another. The researchers were particularly interested in these follow-on errors because they are a sign of the participant reacting badly to negative feedback, either through being distracted or giving up.

But then Faltung and Kiefer split up their male and female groups according to emotional suppression habits. Overall men reported suppressing their emotions more than women, but there was enough variation among the women to create two subgroups – one group who said they mostly let their emotions out, and another group who said they more often suppressed their emotions.

Women who did not habitually suppress their emotions made more total errors on the task than men (both high and low emotional suppressors) and more follow-on errors, but crucially, women who habitually suppressed their emotions performed as well as the men on the rotation task, in terms of total errors and follow-on errors (there was still a tendency for higher performance among men, but the difference in their scores and those of the emotion-suppressing women was not statistically significant).

We must beware over-interpreting such as small study, but the researchers say their results demonstrate an important principle, namely that investigations into potential cognitive differences between the sexes need to take sex differences in emotional strategy into account. Mental rotation ability – often heralded as one of the most robust examples of a sex-linked cognitive difference – may be more about emotions than about visuospatial ability.

This need for nuance in the field of sex-differences research is in addition to other findings that have highlighted the way that cultural pressures can influence sex differences in cognitive performance. For example, it’s been shown that women perform as well as men on maths when competing under an alias, presumably because this removes the pressure not to conform to sex-related prejudices about ability.

Another angle to these new findings concerns emotional regulation strategies. It’s a mistake to think that the male tendency for emotional suppression is inherently superior. In fact emotional suppression is usually considered unhelpful, especially over the longer term, because it’s linked with increased risk of stress and depression. But these findings suggest that in the short term, and in certain contexts, it may be advantageous by helping to avoid the distracting effect of negative feedback.

—Keep calm! Gender differences in mental rotation performance are modulated by habitual expressive suppression

Christian Jarrett (@Psych_Writer) is Editor of BPS Research Digest