A kind of thing that humans can learn during sleep

The industry devoted to “sleep learning” aside, it’s been unclear that people can learn much of anything while they are asleep. An experiment (by much the same team that later noted the phenomenon of contagious sniffing), says it has identified one kind of thing that people can indeed learn while they are asleep:

Humans can learn new information during sleep,” Anat Arzi,  Limor Shedlesky, Mor Ben-Shaul, Khitam Nasser, Arie Oksenberg, Ilana S Hairston and Noam Sobel, Nature Neuroscience, October 2012. vol.  15(10), pp. 1460-5.  The authors, at Weizmann Institute of Science, Loewenstein Rehabilitation Hospital, and the Academic College of Tel Aviv, report:

“During sleep, humans can strengthen previously acquired memories, but whether they can acquire entirely new information remains unknown. The nonverbal nature of the olfactory sniff response, in which pleasant odors drive stronger sniffs and unpleasant odors drive weaker sniffs, allowed us to test learning in humans during sleep. Using partial-reinforcement trace conditioning, we paired pleasant and unpleasant odors with different tones during sleep and then measured the sniff response to tones alone during the same nights’ sleep and during ensuing wake. We found that sleeping subjects learned novel associations between tones and odors such that they then sniffed in response to tones alone. Moreover, these newly learned tone-induced sniffs differed according to the odor pleasantness that was previously associated with the tone during sleep. This acquired behavior persisted throughout the night and into ensuing wake, without later awareness of the learning process. Thus, humans learned new information during sleep.”

Professor Sobel was noted early in his career for the discovery that humans can, if they go about it properly, follow a scent trail across an open field.