In rodents: Probing learning by omitting reinforcement (treats) uncovers latent knowledge & identifies context -not “smartness”- as the major source of individual variability

Dissociating task acquisition from expression during learning reveals latent knowledge. Kishore V. Kuchibhotla et al. Nature Communications, May 2019. https://www.nature.com/articles/s41467-019-10089-0

Abstract: Performance on cognitive tasks during learning is used to measure knowledge, yet it remains controversial since such testing is susceptible to contextual factors. To what extent does performance during learning depend on the testing context, rather than underlying knowledge? We trained mice, rats and ferrets on a range of tasks to examine how testing context impacts the acquisition of knowledge versus its expression. We interleaved reinforced trials with probe trials in which we omitted reinforcement. Across tasks, each animal species performed remarkably better in probe trials during learning and inter-animal variability was strikingly reduced. Reinforcement feedback is thus critical for learning-related behavioral improvements but, paradoxically masks the expression of underlying knowledge. We capture these results with a network model in which learning occurs during reinforced trials while context modulates only the read-out parameters. Probing learning by omitting reinforcement thus uncovers latent knowledge and identifies context -not “smartness”- as the major source of individual variability.

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Popular version -- Study: Treats Might Mask Animal Intelligence. Chanapa Tantibanchachai. News Releases, May 14, 2019. https://releases.jhu.edu/2019/05/14/study-treats-might-mask-animal-intelligence


Rewards are necessary for learning, but may actually mask true knowledge, finds a new Johns Hopkins University study with rodents and ferrets.

The findings, published May 14 in Nature Communications, show a distinction between knowledge and performance, and provide insight into how environment can affect the two.

“Most learning research focuses on how humans and other animals learn ‘content’ or knowledge. Here, we suggest that there are two parallel learning processes: one for content and one for context, or environment. If we can separate how these two pathways work, perhaps we can find ways to improve performance,” says Kishore Kuchibhotla, an assistant professor in The Johns Hopkins University’s department of psychological and brain sciences and the study’s lead author.

While researchers have known that the presence of reinforcement, or reward, can change how animals behave, it’s been unclear exactly how rewards affect learning versus performance.

An example of the difference between learning and performance, Kuchibhotla explains, is the difference between a student studying and knowing the answers at home, and a student demonstrating that knowledge on a test at school.

“What we know at any given time can be different than what we show; the ability to access that knowledge in the right environment is what we’re interested in,” he says.

To investigate what animals know in hopes of better understanding learning, Kuchibhotla and the research team trained mice, rats and ferrets on a series of tasks, and measured how accurately they performed the tasks with and without rewards.

For the first experiment, the team trained mice to lick for water through a lick tube after hearing one tone, and to not lick after hearing a different, unrewarded tone. It takes mice two weeks to learn this in the presence of the water reward. At a time point early in learning, around days 3-5, the mice performed the task at chance levels (about 50%) when the lick tube/reward was present. When the team removed the lick tube entirely on these early days, however, the mice performed the task at more than 90% accuracy. The mice, therefore, seemed to understand the task many days before they expressed knowledge in the presence of a reward.