The Replication Crisis

Successful replications of published research studies make psychologists (and scientists in general) more confident in those findings, but repeated failures tend to cast doubt on the legitimacy of the original article and lead scientists in different directions. For example, we might be eager to take a new drug if a study shows it improves peoples’ memories. But if other scientists cannot replicate the results, we would question the original study’s claims.

Replication is an important tool in “adapting as new data develop.” When results don’t replicate, we ask why – and can design more research to answer that question. Replication is not the same as “further research.” In replication, scientists attempt to repeat the exact methods and study design of the original research. In further research, scientists build on what has already been done, and the questions that rise from prior research. In almost all cases, one study cannot make definitive conclusions about a research question. At best, results from one study apply to the participants in that study (the sample). If we want to say something about a population of people, we need evidence from many studies – we call this generalization of results. Replication studies are one piece of the puzzle.

In recent years, concerns about a “replication crisis” have risen. This has affected several scientific fields, including psychology. Some of the most well-known scientists have produced research that has failed to replicate in another research lab.^[6] In some cases, this might be partially explained by a lack of transparency; there may be important details missing from the original research article that make the “recipe” hard to follow precisely. Also, sample sizes (numbers of participants) in the original studies were often too small and not representative of the general population. There is also a publication bias in psychology, where journals typically only publish significant results that support hypotheses, whereas studies that fail to show significant differences are not made public.

Finally, although psychologists are bound by a code of ethics, a very small number of researchers falsified their results—this is the scientific equivalent of fake news. When false reports are discovered, the original published research articles are often retracted from the scientific journals. Unfortunately, fake scientific news can sometimes have very disturbing and widespread consequences even after they are retracted. A critical example of this in medicine comes from false data about vaccine side effects. In 1998, a team of doctors in the UK led by Andrew Wakefield published a study on 12 children in a highly influential journal called The Lancet^[7] claiming that autism was linked to the measles, mumps, and rubella (MMR) vaccine. Subsequently, the article has been retracted, and the main author, Wakefield, has been discredited by indisputable evidence that he falsified the data. He also failed to get proper consent from the participants and their parents. Since then, many, many other studies have overwhelmingly shown that vaccination is NOT linked to autism. However, Wakefield’s article got a lot of media attention, and parents became reluctant to vaccinate their children, despite the fact that measles can result in blindness, encephalitis (swelling of the brain), pneumonia, and even death. This legacy continues today; increasing numbers of children are unvaccinated and the prevalence of measles is rising dramatically in Europe and the USA.^[8]

 

Bringing it all together

From Lillard’s critical examination of pretend play research to the ongoing debates about note-taking methods, we see how psychological science constantly reevaluates its methods and conclusions. Psychology is a living, evolving discipline. The scientific process —with its emphasis on empirical questions, systematic research, and public knowledge—combined with human creativity and critical thinking, ensures that theories evolve over time. The replication crisis, while challenging, demonstrates the field’s commitment to self-correction and improvement. By embracing new data, refining methodologies, and addressing biases, psychological science continues to strive for more accurate and reliable insights into human behavior and cognition. This adaptive nature strengthens the field and reminds us of the importance of critical thinking, tolerance for ambiguity, and the ongoing nature of scientific inquiry.

The Module 2 Supplement on the following pages describes various approaches to scientific inquiry, including some you may not hear about in your typical classes.

CHAPTER VOCABULARY

• Control of variables
• Correlational study
• Dependent variable
• Direct replication study
• Empirical question
• Experimenter bias
• Generalization
• Hypothesis
• Independent variable
• Longitudinal study
• Negative correlation
• Participant
• Phenomenological approach
• Quantitative research
• Quasi-experiment
• Random assignment
• Replication
• Replication crisis
• Systematic
• Theory