House of Mind

Considering I’ve been suffering from lack of sleep lately, a post about sleep and cognitive performance seems appropriate. I visited this poster on my last day at SfN10 and I finally got around to blogging about it. So here it goes…

Sleep is thought to benefit decision-making and creativity as well as aid in problem-solving, consolidation of memory and transitive relationships. To test the effect of sleep on cognitive performance, Karmakar and others assigned experimental subjects to one of two different sleep sessions and conducted a cognitive task after the 12-hour period. Both groups had 12 hour sessions, but one group had 12 hours (sleep time included, from PM-AM) before the test while the other had 12 hours awake (AM-OM) before the test. For example, the 12 hour session of the sleep group were from 8PM to 8AM and then they went to take the test. 

Results:

1. Sleep improves memory recall. 

2. Sleep increases accuracy of attribute recall. 

3. Sleep decreased the perception of decision quality and the time of day did not account for differences in recall or perceived decision quality. (Individuals who slept before the exam had less confidence and were less satisfied with their choices.)

4. Sleep benefits recall of positive information and hinders recall of negative information.

Author Abstract (Karmarkar et. al): Impact of Sleep on Attribute Recall and Choice Satisfaction

A wealth of recent studies has illustrated a role of sleep in memory but also many other cognitive processes such as problem-solving and creativity. While sleep deprivation has been shown to diminish decision-making, to date, studies have failed to directly investigate the impact of sleep on decision-making or choice. Yet, we often follow the wisdom that “sleeping on it” is beneficial to decisions. Thus, we examined whether periods of sleep influence recall for information pertaining to a decision as well as subjective perceptions of decision quality.

Across studies, participants attended two experimental sessions separated by 12 hrs, either spent awake (AM-PM) or containing sleep (PM-AM). All studies were incentive compatible. During the first session, participants were informed that their selection from a choice set would be honored if they were chosen in a later random drawing. Participants viewed several positive and negative attributes relating to each of four commonly used items (laptop messenger satchels). Following an unrelated filler task, recall was assessed and participants rated the valence of each remembered attribute. In the second session, recall was tested again in a similar manner. After this, participants then indicated their preferred item from the choice set and rated the ease of this decision process, their confidence and their satisfaction with their choice.

Overall, sleep significantly benefited attribute recall. Individuals in the PM-AM group showed an increase in responses, while those in the AM-PM group showed a decrease. These results applied to the total attributes recalled (inclusive of errors) as well as the accurate attributes only. Data from subsequent experiments with balanced numbers of positive and negative attributes suggest that the differences between groups may be due to improved memory for positive compared to negative attributes after sleep. Notably, despite the boost in their knowledgeability, PM-AM participants found the choice process more difficult and were less confident and less satisfied with their decision. These findings do not appear to be dependent on time of day. Single-session control groups, tested in the AM or PM, revealed no differences in baseline recall performance or perceptions of decision quality. Emerging data suggest that single item (yes/no) choices also result in less satisfaction after “sleeping on” decision-relevant information. Thus our results suggest that sleep may have some negative consequences for decision-making, decreasing decision satisfaction, despite improving knowledgeability about the choice set.