Daytime and season do not affect reinforcement learning capacity in a response time adjustment task

ABSTRACT

Seasonal and circadian rhythms have a broad impact on physiological aspects, such as dopamine neurotransmission, and may be involved in the etiology of mood disorders. Considering this, studies on the influence of season and daytime on cognitive function are rare. The present study aimed to assess the impact of seasonal and diurnal effects on the ability to maximize reward outcomes by optimizing response times adaptively. For this purpose, a reward-based learning task that required an adaptation of response time to either a fast or a slow response was used. Eighty German participants (mean age ± SD = 21.86 ± 1.89 years, 41 women) were examined twice, in the morning and in the evening. Half of the participants were tested during the summer, while the other half performed the test in the winter. No impact of daytime, season or of the external factors photoperiodicity and temperature on reinforcement learning could be found. However, a generally slower response speed in the morning compared to the evening appeared. Previously conducted tasks could not display behavioral differences in both times of season and daytime, although neurophysiological findings suggest it.

KEYWORDS:

• Circadian rhythms
• reward learning
• season
• daytime
• response time

Acknowledgements

We would like to thank I. Rostosky and A. Haferkorn for their contribution to the data acquisition. Further, we would like to thank M. Langbehn for programming the clock task.

Disclosure statement

The authors have no commercial associations that might pose a conflict of interest in connection with this manuscript.