Why does psychology struggle so much to achieve meaningful findings? In what has been termed the “replication crisis,” psychology’s much-hyped positive findings typically fail to replicate in later studies, leaving uncertainty about whether the discipline has truly discovered anything of use.
In a new article in Trends in Cognitive Sciences, a team of researchers led by Christiana Westlin at Northeastern University and Lisa Feldman Barrett at Northeastern University, Massachusetts General Hospital, and Harvard Medical School propose a solution. They question the existing assumptions of neuropsychology and provide new ways of understanding the complexity of the brain and mind that might help psychological science move forward from the replication crisis.
“A productive way forward may be to fundamentally rethink what a mind is and how a brain works,” they write.
Many of the most well-known findings in psychology have failed to replicate in later studies; others turned out to have been outright falsehoods. Researchers in a top journal, Nature, have written that almost all brain imaging findings are likely to be false. Some researchers argue that “psychology is incompatible with hypothesis-driven theoretical science” because psychology researchers tend to spin their results to support vague, unfalsifiable theories. Because of this, researchers in the American Psychologist have even written that “everyone knows psychology is not a real science.”
One solution to the replication crisis is focused on the methods used in individual studies. Open science practices, such as pre-registering outcome measures and publishing negative results, can help ensure that spin is kept to a minimum and that researchers don’t adjust their methods repeatedly until they find the results they’re looking for—an activity that is reportedly all too common.
However, according to Westlin and her colleagues, this doesn’t address the issues that are really at the core of psychology’s failures. They write that, at least in neuropsychology, the “foundational assumptions” on which psychological research is based are flawed and thus lead to the failure to find a meaningful, consistent result.
“Methodological rigor is important, but there are other overlooked possibilities: most published studies share three foundational assumptions, often implicitly, that may be faulty,” they write.
These three flawed assumptions are as follows:
- The localization assumption: That a single, identifiable brain structure or neural circuit is involved in creating a psychological experience (for instance, that the experience of “fear” can be traced to a specific brain region or brain pattern);
- The one-to-one assumption: That the neural pattern maps exactly onto the experience, universally (for example, that everyone who feels “fear” has the same brain activation pattern);
- The independence assumption: That neurobiology is the only part of the experience that matters (that the social and environmental context, and the rest of the body, are irrelevant to the brain pattern causing the psychological experience of “fear”).
This leads researchers to study the brain and mind in a certain way. Because of the assumption that the environmental context doesn’t matter, for instance, researchers study neurobiology in the lab and assume that this will generalize to real life.
As an example, researchers might study fear by showing someone a horror movie while hooked up to an MRI to measure brain activity. They might then suggest that the experience of fear—and whatever brain pattern they detected along with it—is the same as it would be for someone experiencing a horrific event in real life. But this assumption may be flawed: after all, people might feel fear differently in real life than when they watch a scary movie, especially watching a scary movie while knowing you are part of a psychological study!
Instead of these flawed assumptions, the researchers propose three new ones:
- The whole-brain assumption: Rather than a single piece of neurobiology creating a psychological experience, the researchers propose that the whole brain works in different ways to create the experience, with various parts more or less active, in a complex, interconnected system.
According to the researchers, brain scan studies typically focus on only the strongest signals, highlighting the biggest spike of activity and dismissing the vast complexity of constant brain signalling as “noise.” But the researchers argue that this “noise” may be an integral part of the brain’s functioning, as the whole pattern works to create an experience.
They add that brain scans use modelling to determine which signals to focus on—and the way this is done leads researchers to focus on the very signals they are hoping to find while ignoring as “noise” any other brain activity.
- The many-to-one assumption: Rather than one universal neurobiological state, the researchers propose that various complex whole-brain changes can all lead to the same experience (eg, “fear”) despite appearing differently on an MRI.
One often overlooked aspect of this is that everyone’s experience of that psychological state is different. One person may enjoy the feeling of suspense or fear generated by a horror movie, while another may hate that feeling! These are not likely to be caused by the same exact brain activity—despite the same stimulus.
- The complexity assumption: The whole body, as well as the environment, are integral parts of an experience. People feel fear throughout their bodies, and it can be exacerbated by their perceptions of their bodily reactions, even if these are unconnected to the stimulus.
For instance, if someone is already feeling nauseated or their heart rate is already high (say, from exercising), they may experience a horror movie as more disgusting or scary. And the environment matters too—watching a horror movie in a brightly lit room with your friends is pretty different from watching it alone with the lights off.
Moreover, even just the brain functioning aspect is a complex, interconnected system that is more than just the sum of its parts. Contrary to popular belief, the researchers write, the brain is not much like a machine:
“The machine metaphor implies that the system can be broken down into independent, separable mechanisms, where each mechanism can be studied independently of one another. But many domains of biology have shown that biological systems cannot be studied as independent mechanisms, because the systems’ functions emerge through the collective interaction of their parts. Instead, biological systems are thought to function as complex systems, where many weak, causal factors interact in a nonlinear way to produce a larger-scale collective outcome.”
In the end, the researchers suggest rethinking these assumptions can help rebuild psychological science from the ground up. Instead of wasting resources to try to find single brain circuits for presumed universal psychological states, studies can be designed to look at the complexity of the brain, body, and environment. Perhaps this reinvention can allow scientists to investigate the vast and unique experiences of human nature with humility.
“We have suggested that mental events arise from a complex ensemble of signals across the entire brain, as well as the from the sensory surfaces of the body that inform on the states of the inner body and outside world, such that more than one signal ensemble maps to a single instance of a single psychological category (maybe even in the same context),” the researchers write.
“To this end, scientists might find inspiration by mining insights from adjacent fields, such as evolution, anatomy, development, and ecology, as well as cybernetics and systems theory. At stake is nothing less than a viable science of how a brain creates a mind through its constant interactions with its body, its physical environment, and with the other brains-in-bodies that occupy its social world.”
Westlin, C., Theriault, J. E., Katsumi, Y., Nieto-Castanon, A., Kucyi, A., Ruf, S. F., . . . & Barrett, L. F. (2023). Improving the study of brain-behaviour relationships by revisiting basic assumptions. Trends in Cognitive Sciences. Published online February 02, 2023. https://doi.org/10.1016/j.tics.2022.12.015 (Link)
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