Sleep and incubation: using problem reactivation during sleep to study forgetting fixation and unconscious processing during sleep incubation

ABSTRACT

When people are stuck on a problem, they sometimes benefit from an incubation period—a break from working on the problem. Anecdotes and empirical evidence suggest that sleeping during incubation is useful, but the mechanisms remain poorly understood. We examined how targeted memory reactivation during sleep, which boosts next-day solving, relates to forgetting fixation, a well-supported explanation of awake incubation. In evening sessions, participants attempted puzzles, while a unique sound cue played during each puzzle. Half the time, puzzles included fixating information reinforcing an incorrect representation. Later, during deep sleep, sounds associated with half of participants’ previously unsolved puzzles were presented. The sounds should strengthen puzzle memories and reduce forgetting of the fixating information. In morning solving, overnight cueing reliably interacted with fixating information: participants solved numerically more cued than uncued puzzles, but only when puzzles included fixating information. These results suggest that additional processing occurred beyond simple fixation forgetting.

KEYWORDS:

• Problem solving
• incubation
• sleep
• targeted memory reactivation
• restructuring

Acknowledgements

We thank Ken A. Paller, Susan Florczak, Todd Anderson, Daniel Wetmore, and Sheepdog Sciences for the use of, and help with, the sleep monitoring and cueing system devices. We additionally thank Christopher Krause, Lane Patterson, Sophia McCullough, Alec Friswold, and James Crisafulli for data-collection and memory-coding assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data that support the findings of this study are available at https://osf.io/bucpe/.

Notes

1 This analysis incorporates the t test statistic and degrees of freedom from the original study into the analysis to derive a Bayes Factor (BF) that indicates the likelihood that the replication data more closely reflect the hypothesis that Cued puzzles are solved more than Uncued puzzles, or the null hypothesis. BFs greater than 1 indicate evidence for the experimental hypothesis, BFs less than 1 indicate evidence for the null hypothesis. Generally BFs between 0.33 and 3 are considered inconclusive while BFs less than 0.1 or greater than 10 are considered strong evidence (Wetzels et al., 2011).

Additional information

Funding

This work was supported by the National Institutes of Health’s National Institute of Child Health and Human Development awarded to M. Beeman under grant R03HD087111.