The inevitability of variation in human behavior is a phenomenon psychologists have long recognized and developed statistical methods to account for in their analyses. Human behavior varies not only between people, but within separate instances for one individual as well.
The study of that individual variability, called "noise" by many psychologists, is the topic of focus in a special issue of Perspectives on Psychological Science , published in March 2025.
Joakim Sundh and his coauthors from Uppsala University set the stage for this discussion by first providing an historical review of how noise has previously been studied in psychological research. They argue that noise is typically studied as an external factor that needs to be minimized rather than an internal factor that can provide information about the process being studied.
"All noise has a source, and different sources of noise can give rise to different expressions of noise," they wrote. "If these different sources of noise are associated with distinct processes, then one can use the way noise is expressed in data to draw conclusions regarding those processes."
Sundh and his team also describe their own research with their Precise/Not Precise (PNP) model, which was developed to help determine how different sources of noise are associated with different psychological processes. They apply the PNP model to three experiments, illustrating how distributions of noise can be studied to determine analytic and intuitive ways of reasoning (Sundh et al., 2025).
The authors end by previewing the three additional contributions to the special issue, concluding that each of the papers "represent excellent example of the possibilities inherent in using noise to inform scientific inquiry by treating it as a source of information."
Adam Sanborn and his team from the University of Warwick expand on this discussion by exploring the purpose of noise in the human thought process.
"Asking participants to perform the same task on multiple occasions, even when those occasions are close together in time, produces surprisingly noisy behavior," the authors wrote.
Is that noise an error in our cognitive processes or does it actually help us perform better? To answer this question, Sanborn and his coauthors discuss the role of noise throughout the stages of information processing, from perception to computation to response. They argue that it is more accurate to view noise as a feature of cognitive processing rather than a glitch that disrupts it (Sanborn et al., 2025).
"Not only could one say that 'noise' in cognition is a feature and not a bug, but even that it is an essential feature, which underpins our ability to deal with an uncertain world of such complexity that precise analysis is computationally impossible," Sanborn and his coauthors wrote.
Though noisy behavior is widely acknowledged as inevitable, in many cases it is preferable for individuals to be consistent in how they categorize information. For example, a doctor assessing for the presence of skin cancer is expected to make a consistent and correct diagnosis every time. In their study, Florian Seitz (University of Basel) and his coauthors work to better understand the ways noise can be reduced as individuals categorize information.
To do this, they present a simulation that accounts for possible sources of behavioral variability during the process of perceiving and processing information. In their simulation Seitz and colleagues used two common category structures: (1) rule-based structures where a category is based on a single feature, and (2) information-integration structures where a category is determined by multiple features that are considered simultaneously. The researchers argue that by integrating continuous data into experiments that assess categorization, researchers may be better able to identify the sources of behavioral noise and categorize the cognitive processes at play (Seitz et al., 2025).
"Assessing people's category beliefs in a continuous way may therefore help disentangle perceptual and process-related sources of behavioral variability," Seitz and his team wrote, adding that this finding could inform both future cognitive models and applied interventions.
Inspired by recent chaotic responses to current events like the COVID-19 pandemic and ongoing campaigns of misinformation, APS Fellow Michel Regenwetter and his team from the University of Illinois at Urbana-Champaign explore the presence of irrational moral judgement. They use the concept of transitivity as a foundation for their discussion. This philosophical concept is used in discussions of morality as a kind of logic equation— the understanding that if A is better than B, and B is better than C, then A is better than C.
Regenwetter and his coauthors investigate whether participants can be described by the principle of transitivity, despite the large amount of variation in their behavior. Their study included 28 participants from the Urbana-Champaign, Illinois, area. Each participant was presented with a survey of 126 moral vignettes, each of which was accompanied by a binary-choice question. For each vignette, they were instructed to choose the option that was "worse" or the most "morally wrong."
Based on their sample, the team found that participants did adhere to transitive moral thinking, suggesting that a shared set of moral principles underlies how people judge the moral value of one item over another (Regenwetter et al., 2025).
"Despite the amazing heterogeneity of behavior in the world around us, there may be order underneath the chaos," they wrote.
References
Regenwetter, M., Currie, B., Huang, Y., Smeulders, B., & Carlson, A. (2025). (Ir)rationality of moral judgement . Perspectives on Psychological Science, 0(0).
Sanborn, A. N., Zhu, J., Spicer, J., Leon-Villagra, P., Castillo, L., Falben, J.K., Li, Y., Tee, A., & Chater, N. (2025) Noise in cognition: Bug or feature? Perspectives on Psychological Science, 0(0).
Seitz, F., Jarecki, J., Rieskamp, J., & von Helversen, B., (2025). Disentangling perceptual and process-related sources of behavioral variability in categorization . Perspectives on Psychological Science, 0(0).
Sundh, J., Millroth, P., Colsioo, A., & Justlin, P. (2025). Enriching psychological research by exploring the source and nature of noise . Perspectives on Psychological Science, 0(0).
