Buying a house is a complicated and important decision that requires weighing risks against benefits. Common wisdom says we should "sleep on it" before officially making an offer or signing the contract. In fact, there is scientific support for this advice: performance on complex decision-making tasks, like the Iowa Gambling Task, is disrupted by sleep deprivation and enhanced by post-learning sleep.
In a new paper published in Behavioral Neuroscience, Seeley and colleagues (2016) (PDF, 180KB)opens in new window tested the sleep stage and cortical activity underlying the beneficial effect of sleep on complex decision making.
Polysomnogram recordings were taken during sleep between two sessions of the Iowa Gambling Task. In the Iowa Gambling Task, participants choose cards from one of four decks (A, B, C, D) that vary in the magnitude and frequency of monetary rewards and punishments. Decks A and B are "bad decks," because although they have high reward, they also have high punishment; decks C and D are "good decks" because they have low reward and low punishment.
Initially, decision-makers show a preference for the decks within each bad/good pair with low-probability of punishment (p = .1; B and D) compared to those with high-probability punishment (p = .5; decks A and C). However, optimal performance requires shifting choices away from deck B – although punishment is less probable for deck B, it is large, which outweighs the benefits of the high reward.
Consistent with previous studies, in Session 1 participants preferred high value/low-probability punishment deck B. However, this preference was reduced after sleep. Furthermore, the magnitude of this reduction in deck B choices in Session 2 was correlated with the magnitude of theta activity during rapid eye movement (REM) sleep in the left and right medial prefrontal cortex and the left lateral prefrontal cortex.
The authors speculate that theta activity in the left prefrontal cortex may reflect online monitoring of unexpected outcomes and more general learning processes, whereas theta activity in the right prefrontal cortex may reflect emotional insight into the task or processing information that was below conscious awareness.
Indeed, the relationship between right prefrontal cortex activity and emotional or subconscious insight is supported by the fact that participants who had some notion that deck B was bad in Session 1, as indicated by higher skin conductance responses prior to deck B choices, showed larger changes in theta activity in the right prefrontal cortex during REM sleep after Session 1 compared to a baseline measure taken the night before Session 1.
Theta activity during REM sleep was not correlated with either behavioral changes or skin conductance responses for the other decks, suggesting that sleep-related changes in performance were specific to insight about deck B.
Thus, although more work is needed to determine the origin of theta activity in the prefrontal cortex during REM sleep, these results suggest that sleep can improve complex decision-making by enhancing emotional insight.
Citation:
- Seeley, C. J., Smith, C. T., MacDonald, K. J., & Beninger, R. J. (2016). Ventromedial prefrontal theta activity during rapid eye movement sleep is associated with improved decision-making on the Iowa Gambling Task. Behavioral Neuroscience, 130(3), 271–280. https://dx.doi.org/10.1037/bne0000123
Note: This article is in the Basic / Experimental Psychology topic area. View more articles in the Basic / Experimental Psychology topic area.