Motivation, Learning and Memory (Part 2)


Do monetary (extrinsic) rewards enhance motivation and/or memory consolidation?

I’ve been very clear in the past about my issues with school incentive schemes and how they don’t necessarily produce the intended results (here and here). That said, research conducted by Kou Murayama (University of Reading) and Christof Kuhbandner (University of Munich) suggests that the cognitive and neurological processes involved are even more complicated than I thought.

The assumption that extrinsic rewards are an effective and reliable way to enhance motivation in students remains very strong, with several companies now making a considerable profit through selling their schemes to schools.

But does money (or Xbox games, iTunes vouchers, etc.) really lead to greater motivation and performance?

The answer is far from clear. Neurological findings appear to suggest they do. It has been discovered that monetary rewards promote memory consolidation by activating the mesolimbic reward system, which increases dopamine release in the hippocampal memory system.

But there are problems with this…

Studies have found that hippocampus-dependent memory consolidation requires an extended period of time to complete so that the effects of money on memory manifest themselves only after some time has elapsed. However, very little research has been conducted into the impact of money at different time points (for example, immediately after encoding or after a delay).

Another problem is highlighted by motivational psychology. Psychological studies have found that monetary rewards can actually undermine task engagement, especially for ‘interesting’ tasks. The generally held view is that extrinsic rewards can ‘crowd out’ the intrinsic value of the interesting task – this process is known as the ‘undermining effect’.

What’s interesting to note here is that the ‘undermining effect’ only seems to occur when the task is interesting.

This is pretty much what Murayama and Kuhbandner found. Participants were divided into two groups (money group and no-money group) and presented with a list of trivia questions. Some of the questions had been classed as uninteresting (e.g. “What is the name of the author of the book 1984?”) while others had been classed as interesting (e.g. “What is the only consumable food that won’t spoil forever?”) – the classifications of interesting and uninteresting had been decided by a panel of independent judges.

Both groups were presented with the trivia questions that they had to answer. This was followed by an immediate memory test then a time-delayed memory test one week later.

…they discovered:

  • Monetary rewards helped memory only after a delay
  • Monetary rewards helped memory only when the material was uninteresting
  • Monetary rewards had little impact on memory when the material was considered interesting

…and now for some neuroscience:

The striatum is a subcortical part of the forebrain and is thought to be responsible for executive functions and working memory but is also responsible for reward induced memory consolidation. fMRI studies conducted by Murayama et al (2010) found that extrinsic rewards appeared to dampen down activation of the striatum, but only when the task was considered to be interesting. This would suggest that paying someone to do a task they love could actually make them worse at it!

Striatum - active and inactive

Striatum – active and inactive


It seems odd that we could actually negatively affect the learning of students through extrinsic rewards, but this is (in part) what this research is suggesting. If the student is genuinely interested in the subject area, extrinsic rewards could actually prevent the learning from taking place because the area of the brain needed to induce memory consolidation has been dampened down by the extrinsic reward. This has been posited for some time (for example, as far back as 1973, Stanford psychologist Mark Lepper discovered that rewarding young children for something they loved to do actually led to a reduction in motivation within two weeks of the implementation of the incentive scheme). With the evidence from brain scans the hypothesis is strengthened further.

On the positive side, extrinsic rewards work for the boring stuff – just not straight away.

The problem is that not all students find the same things interesting and others are motivated by other factors unrelated to extrinsic rewards. There is also an ecological validity issue here (as there is with all laboratory-based experiments) as well as the continuing discussions surrounding the interpretation of brain scans.

Nevertheless, all this does suggest that we should be cautious before we begin to employ extrinsic rewards.


Murayama K & Kuhbander C (2011) Money enhances memory consolidation – But only for boring material. Cognition 119, 120-124

Murayama K, Matsumoto M, Izuma K & Matsumoto K (2010) Neural basis of undermining effect of monetary reward on intrinsic motivation PNAS doi: 10.1073/pnas.1013305107


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