Convergent creativity was tapped with the 'remote associates test', which required the students to identify the one word that matched three other words (e.g. for 'time', 'hair' and 'stretch' the answer would be 'long'). In this case, eye blink rate was negatively related with divergent creativity - the less a student blinked the better they tended to do at this task.
Why should eye blink rate be associated with creativity? The study authors Soghra Chermahini and Bernhard Hommel explained that eye blink rate is a marker for dopamine activity and in turn, dopamine has previously been linked with creativity.
The researchers pointed to evidence showing, for example, that patients diagnosed with schizophrenia, which is associated with excess dopamine, tend to have high eye blink rates. Patients with Parkinson's, by contrast, which is associated with reduced dopamine, show low eye blink rates. They also highlighted past research linking dopamine with creativity. For example, there's evidence that positive mood - which is related to dopamine levels - can enhance creativity, although the results in this area have been extremely inconsistent.
Chermahihin and Hommel said their research adds to the literature by showing that the dopamine-creativity link is far from straight-forward. There was a negative linear relationship with convergent thinking but a positive, inverted U-shaped relationship with divergent thinking. This could help explain the inconsistent research findings linking mood with creativity, as they explained:
'Participants with a relatively low level of dopaminergic functioning would be likely to benefit from better mood, whereas people with a relatively high level of dopaminergic functioning, such as individuals scoring high in psychoticism, would actually be expected to suffer from better mood. Depending on which part of the distribution happens to be more strongly represented in a given sample, the corresponding study may find a positive, negative, or no relationship between mood and the given performance measure.'_________________________________
Chermahini, S., & Hommel, B. (2010). The (b)link between creativity and dopamine: Spontaneous eye blink rates predict and dissociate divergent and convergent thinking. Cognition, 115 (3), 458-465 DOI: 10.1016/j.cognition.2010.03.007