Latent learning is a form of learning that is not immediately expressed in an overt response; it occurs without any obvious reinforcement of the behavior or associations that are learned. Interest in latent learning arose largely because the phenomenon seemed to conflict with the widely held view that reinforcement was necessary for learning to occur.
In a classic experiment by Edward C. Tolman, three groups of rats were placed in mazes and their behavior was observed each day for more than two weeks. The rats in Group 1 always found food at the end of the maze; the rats in Group 2 never found food; and the rats in Group 3 found no food for 10 days, but then received food on the eleventh. The Group 1 rats quickly learned to rush to the end of the maze; Group 2 rats wandered in the maze but did not preferentially go to the end. Group 3 acted the same as the Group 2 rats until food was introduced on Day 11; then they quickly learned to run to the end of the maze and did as well as the Group 1 rats by the next day. Other experiments showed that latent learning can happen in shorter amounts of time such as in three or seven days. Among other early results, it was also found that animals that were allowed to wander in the maze but were detained for one minute in the empty goal box then learned the maze much more rapidly than groups that were not given such goal orientation.
Rats were placed in a T-maze in which one arm was white and the other black. One group of rats had thirty minutes to explore this maze with no food present, and the rats were not removed as soon as they had reached the end of an arm. The experimenters then placed food in one of the two arms. Rats in this exploratory group learned to go down the rewarded arm much faster than another group of rats that had not previously explored the maze.
Latent learning was examined through use of a water maze. Rats were required to escape a water maze while satiated for food, with food located on one of the escape platforms. Upon being returned to the maze while food deprived, the rats learned where the food was located at a rate that increased with the number of pre-exposures given the rat in the training phase. This indicated varying levels of latent learning.
Most early studies of latent learning were done with rats, but a study by Stevenson explored the phenomenon in children. Stevenson required children to explore a series of objects to find a key, and then he determined the knowledge the children had about various non-key objects in the set-up. Latent learning was found in children; that is, they found non-key objects faster if they had previously seen them. Their ability to learn in this way increased as they became older.
Wirsig et al. (1982)
The taste of sodium chloride was used to explore which parts of the brain are necessary for the latent learning function in rats. Decorticate rats were just as able as normal rats to accomplish the latent learning task.
Some work with humans
An experiment with infants explored latent learning at an early age. Three-month olds were exposed to two different hand puppets simultaneously. Then the infants were periodically presented with one of the puppets until they reached 6-months of age, at which point a target behavior was demonstrated on the first puppet. Finally, the infants were presented with the alternate puppet and performed the target behavior on that puppet at a higher rate than the control group who had not seen the two puppets paired. This suggests that the pre-exposed infants had formed an association between the puppets without obvious reinforcement.
Another experiment suggested that not all potential associations are easily formed by latent learning. Human participants undeprived of caffeine were given a novel caffeinated drink for four days and then were given the drink on a caffeine-deprived fifth day. These participants did not show an increased liking for the flavor upon being caffeine-deprived, while subjects who underwent the same procedure while deprived of caffeine every day showed an increased liking for the flavor each day. In this case, flavor quality as a function of caffeine did not seem to be acquired through latent learning.
There have been a few indications as to the neural processes involved in latent learning. In one study, patients with medial temporal amnesia had particular difficulty with a latent learning task which required representational processing. Another study, done with mice, found intriguing evidence that the absence of a prion protein disrupts latent learning and other memory functions in the water maze latent learning task, while phencyclidine was found to impair latent learning in mice on a water finding task.
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- Karn, H. W.; Porter, J. M., Jr. (1 January 1946). "The effects of certain pre-training procedures upon maze performance and their significance for the concept of latent learning.". Journal of Experimental Psychology 36 (5): 461–469. doi:10.1037/h0061422.
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- Wirsig, Celeste R.; Grill, Harvey J. (1 January 1982). "Contribution of the rat's neocortex to ingestive control: I. Latent learning for the taste of sodium chloride.". Journal of Comparative and Physiological Psychology 96 (4): 615–627. doi:10.1037/h0077911.
- Campanella, Jennifer; Rovee-Collier, Carolyn (1 May 2005). "Latent Learning and Deferred Imitation at 3 Months". Infancy 7 (3): 243–262. doi:10.1207/s15327078in0703_2.
- Yeomans, Martin; Ripley, Tamzin, Lee, Michelle, Durlach, Paula (2001). "No evidence for latent learning of liking for flavours conditioned by caffeine". Psychopharmacology 157 (2): 172–179. doi:10.1007/s002130100765.
- Myers, Catherine E.; McGlinchey-Berroth, Regina, Warren, Stacey, Monti, Laura, Brawn, Catherine M., Gluck, Mark A. (1 January 2000). "Latent learning in medial temporal amnesia: Evidence for disrupted representational but preserved attentional processes.". Neuropsychology 14 (1): 3–15. doi:10.1037/0894-4184.108.40.206.
- Nishida, Noriyuki; Katamine, Shigeru, Shigematsu, Kazuto, Nakatani, Akira, Sakamoto, Nobuhiro, Hasegawa, Sumitaka, Nakaoke, Ryota, Atarashi, Ryuichiro, Kataoka, Yasufumi, Miyamoto, Tsutomu (1 January 1997). Cellular and Molecular Neurobiology 17 (5): 537–545. doi:10.1023/A:1026315006619.
- Noda, A. "Phencyclidine Impairs Latent Learning in Mice Interaction between Glutamatergic Systems and Sigma1 Receptors". Neuropsychopharmacology 24 (4): 451–460. doi:10.1016/S0893-133X(00)00192-5.