Do you know that feeling when someone is trying to explain something you already know? Maybe your GPS is trying to tell you how to get to your own house. Annoying, right? But imagine you’ve just arrived in an unfamiliar city: any hint is welcome. This phenomenon, in which well-intentioned help sometimes does more harm than good, is known as the “expertise-reversal effect” in educational research.

Recently, Tetzlaff and colleagues published an extensive meta-analysis on this effect. Simply put, the expertise-reversal effect shows that beginners learn better when they receive extra guidance, while advanced learners are better off when they receive less guidance.

Why does this happen? Beginners lack the prior knowledge to perform complex tasks without help. For them, additional explanations or clear step-by-step plans give their learning process a big boost. But advanced learners already have enough knowledge, which can make the same explanation redundant and even distracting.

The analysis by Tetzlaff and his team not only confirms that this effect is strong but also emphasises that it is especially powerful for beginning students. Additional support for beginners, therefore, has a greater positive effect than omitting unnecessary support for experts. In concrete terms, this means that if you are in doubt, it is better to provide too much guidance than too little.

However, there is also nuance. The effect appears to be less pronounced in young students and within specific subject areas such as languages ​​and humanities. This may be because tasks within these subject areas are less ‘complex’ or interactive, which means that the advantage of extra support is less pronounced. Moreover, the expertise-reversal effect is not symmetrical: offering additional help to beginners has a more substantial positive impact than reducing help for advanced students. So you run less risk with more help than with less.

What does this mean for you, whether you teach, train, or coach people? The key insight is that it pays to check what someone already knows before offering help. Beginners will be grateful if you help them get started, but advanced learners will grow even more if you give them the space to work independently. That way, you get the most out of every learning process.

Abstract of the meta-analysis :

Background
Different learners thrive under different instructional conditions, thus requiring adaptivity. Such differential effects became known as aptitude-treatment interactions (ATIs). An example of an ATI is the expertise reversal effect. The expertise reversal effect is present when instructional assistance leads to increased learning gains in novices, but decreased learning gains in experts.
Aims
We conducted a meta-analysis to evaluate the strength of the expertise reversal effect as well as to identify potential moderators.
Sample
A standardized literature search was conducted in the online databases PsycINFO and ERIC in December 2022 and November 2024. Of 1590 identified studies, 176 effect sizes from 60 experimental studies and a total of 5924 participants were finally included in the meta-analysis.
Methods
The meta-analysis followed the PRISMA guidelines (Page et al., 2021). The data was analyzed using the metaphor package in R, accounting for dependency among effect sizes.
Results
Low prior knowledge learners learn better from high-assistance instruction (d = 0.505). High prior knowledge learners learn better from low-assistance instruction (d = −0.428). These effects are moderated by the type of prior knowledge assessment, the educational status of the sample, and the domain of the learned content.
Conclusion
Our results suggest that the expertise reversal effect is robust across a wide variety of contexts. However, for younger students and some fields of study (ie, humanities and language learning), the evidence for effectiveness is less clear.
Furthermore, the expertise reversal effect is not symmetrical: providing novices with assistance has a stronger effect than withholding assistance from experts.