It is human nature to seek out explanations for phenomena in the natural world, and one of the main goals of the modern practice of science is to construct such explanations. A long tradition in philosophy has studied scientific explanations in general, proposing frameworks for deciding which explanations are true and what form such explanations should take (e.g., Garfinkel, 1981; Hempel & Oppenheim, 1948; Strevens, 2008). Explanations of psychological phenomena have posed a particularly interesting set of puzzles, as scholars have debated whether such explanations should fruitfully be made at the level of the mind or reduced to talk about the brain (van Riel & Van Gulick, 2016). In this article, we consider the question of whether people prefer reductive explanations for psychology and explore how people’s explanatory preferences may shape their understanding of science in general.
Explanatory reduction
While explanations can take many forms, one common form is reductive: providing an explanation of a phenomenon in terms of smaller component parts or more fundamental processes (see Craver, 2007). Issues of reduction are not unique to psychology and neuroscience, as this explanatory form can be found across the sciences. Consider the relationship between chemistry and physics, for example. While it is logically possible that atoms (and other elements of a physical ontology) could exist without there being any molecules, it is not logically possible that molecules could exist without atoms. Atoms, then, are logically prior to molecules. If an explanation of a molecular phenomenon is translated in terms of atoms, and if the atomic translation does not omit any aspect of the molecular version of the explanation, then we can say that the explanation has been reduced from the chemical to the physical level (Kemeny & Oppenheim, 1956; Oppenheim & Putnam, 1958).
Similarly, in the case of psychology, brains can exist without our having to postulate minds. But if brains are responsible for executing mental processes, then minds cannot exist without brains. Brains are in this sense prior to minds, as atoms were prior to molecules in the previous example. Accordingly, neuroscientists often attempt to explain the neural processes that underlie behavioral, perceptual, and cognitive phenomena. A reductive neuroscientific explanation of a psychological phenomenon is successful if it adequately captures all the features of the phenomenon at the neural level of description.
In practice and in theory, reduction is easier between some sciences than others. Since molecules necessarily include atoms in their definitions, reducing a chemical unit (molecule) to a group of physical units (atoms) is relatively straightforward. But the ontological units of psychology are not so neatly identified. According to some theories, neural processes are not logically necessary constituents of conscious experiences or intentional behaviors. Further, psychological explanations often rely heavily on theoretical inference. Therefore, any attempt to reduce the psychological to the neural will itself rely upon theoretically informed, psycho-neural bridge laws (e.g., Nagel, 1961). To date, there is no scientific consensus regarding the structure of such laws, nor is there consensus regarding what counts as a scientific law generally, even within a discipline (Godfrey-Smith, 2008). This means that there is no generally agreed upon proper form for explanations of psychological phenomenon.
The case of seductive allure
Regardless of the objectively correct form for explanations in psychology, these might not be the explanations that people subjectively find satisfying. Indeed, prior work has found that people’s subjective sense of understanding or satisfaction is often decoupled from whether or not an explanation is accurate (Trout, 2002, 2016). For example, people tend to prefer teleological explanations even when they are not appropriate, as for natural phenomena (Lombrozo & Carey, 2006). People also prefer longer explanations (Kikas, 2003; Langer, Blank, & Chanowitz, 1978), explanations with more causal factors (Zemla, Sloman, Bechlivanidis, & Lagnado, 2017), and explanations that additionally provide a vacuous label for a phenomenon (Giffin, Wilkenfeld, & Lombrozo, 2017).
One particular instance of this kind of error in explanatory preferences is known as the seductive allure effect: people without advanced training prefer explanations for psychological phenomena when those explanations include a neuroscience component, even when that component is irrelevant to the logic of the explanation. In the initial demonstration of this phenomenon, participants judged explanations for psychological phenomena that were either good or bad (i.e., circular) and that either did or did not contain irrelevant neuroscience jargon. This jargon was irrelevant primarily because it merely translated information already present in the description of the phenomenon into neuroscientific terms (e.g., replacing “how people process faces” with “how the fusiform face area in the brain responds to faces”); expert neuroscientists agreed that this added jargon did not explain why the phenomenon happened.
Participants tended to accurately judge the bad explanations as less satisfying than the good ones, but they also judged that explanations containing irrelevant neuroscience language were more satisfying, particularly the bad ones (Weisberg, Keil, Goodstein, Rawson, & Gray, 2008). Although neuroscience information is not seductive in all circumstances (Diekmann, König, & Alles, 2015; Scurich & Shniderman, 2014), this effect has been replicated both directly (Fernandez-Duque, Evans, Christian, & Hodges, 2015; Weisberg, Taylor, & Hopkins, 2015) and conceptually (Rhodes, Rodriguez, & Shah, 2014). Additionally, similar effects have been found in other domains. For example, bogus mathematical terms in paper abstracts about biology and social science phenomena led participants to rate these abstracts more highly (Eriksson, 2012).
Why does this effect happen? Several possibilities have been discussed in the literature, and these explanations generally fall into two categories: those that emphasize the unique properties of psychology or neuroscience and those that see this as an instance of more general issues in judging scientific explanations in all fields. In terms of the first category, the most prominent possibility is that people are naïve dualists, assuming that brain processes and mental processes are separate (e.g., Harris & Richert, 2008; Preston, Ritter, & Hepler, 2013; see reviews in Bloom, 2004; Musolino, 2015). Because neuroscience provides evidence that this assumption is false, neuroscience information becomes correspondingly more surprising and hence attractive. Other explanations in this category point to the fact that neuroscience uses expensive equipment (e.g., NIH’s $150 million BRAIN Initiative) and produces visually appealing images (McCabe & Castel, 2008). Yet another possibility along these lines is that psychology is not seen as scientific (Keil, Lockhart, & Schlegel, 2010; Lilienfeld, 2012), and so adding any other type of information to psychological explanations makes them seem better.
In terms of the second category, the seductive allure of neuroscience could be an instance of a more general preference for reductive explanations. The sciences can be seen as being organized in a reductive hierarchy, whereby social science (i.e., studies of the behavior of groups of people) could be reduced to psychology (i.e., studies of individuals’ behavior), which in turn could be reduced to neuroscience (i.e., the brain processes that underlie behavior), and so on through biology, chemistry, and physics (see Fanelli & Glänzel, 2013; Smith, Best, Stubbs, Johnston, & Archibald, 2000). On this explanation, people prefer neuroscience language in explanations of psychological phenomena not necessarily because of a fascination with neuroscience per se, but because they believe that reductive explanations are superior in general.
A recent study found empirical support for this latter explanation by presenting participants with scientific phenomena across six different fields (social science, psychology, neuroscience, biology, chemistry, and physics). As in the initial demonstration of the seductive allure effect, participants read one of four explanations for each phenomenon, crossing good or bad with the presence or absence of irrelevant language from the immediately more reductive field (e.g., an explanation for a biological phenomenon that either did or did not include irrelevant language from chemistry). Participants judged explanations that contained the irrelevant reductive language as better across the sciences (Hopkins, Weisberg, & Taylor, 2016). This finding suggests that the seductive allure of neuroscience is a more specific instance of a general preference for reductive explanations: a reductive allure.
However, the effect of bogus reductionist language was somewhat stronger for explanations that reduced psychology to neuroscience. This suggests that neuroscience additionally has some unique features that might play an independent role in people’s judgments. What is it about neuroscience that leads to this special attraction? Or, conversely, what is it about psychology that makes people more likely to prefer a reductionist explanation for these phenomena? The current study was designed primarily to answer these questions, using a different method than in previous work. Rather than asking participants to rate explanations, we presented participants with scientific phenomena and asked them to select which investigative methods (e.g., “analyzing neural activity”) they thought would be appropriate for a variety of scientific phenomena. The main impetus behind using this method was to provide participants with more freedom to tell us about how they see the inter-relations among sciences, serving as a proxy for their explanatory preferences. By providing only brief descriptions of methods without any specific content, this task avoids a potential criticism levied at earlier work: that the irrelevant reductionist information included in the explanations used in those studies may have genuinely improved these explanations in some way, even though it was verified by experts to be non-explanatory. This current task, by providing only abstract investigative methods, ensures that participants are choosing among exactly the same kind of information for every item.
Another advantage of the current method is that it allows us to investigate a wider range of questions than previous work, specifically the issue of how people view reduction across the entire scientific hierarchy. Hopkins et al. (2016) provided participants with explanations that included language from the immediately more reductive level (e.g., chemistry for a biology phenomenon), but that study did not investigate whether there was a general preference for ever-more reduction (e.g., physics for a biology phenomenon). After all, many arguments in science and philosophy emphasize that the ultimate source of all of these phenomena are physics, or at least that all scientific explanations will ultimately consist of physical terminology (e.g., Carnap, 1937; Neurath, 1931; see Huttemann & Papineau, 2005; Stoljar, 2010 for analyses). Do people agree that this is the right way to explain all of science; are people maximally reductive? Previous work also has not investigated whether people might prefer explanations at a higher level (e.g., social science for a psychology phenomenon). Are there cases where referring to the larger or higher-order structures provides a satisfying explanation for a particular phenomenon?
The current study thus aimed to investigate the issue of whether and how the relationship between psychology and neuroscience might be special in the context of the full reductive hierarchy of the sciences using a novel method to explore this question: asking participants to select which methods would be appropriate for investigating phenomena from five different sciences. This method allowed us to investigate four main hypotheses. First, based on findings from previous work, we predicted that people would be more likely to choose neuroscience as an investigative method for psychological phenomena than to choose reductive methods for any other science; neuroscience itself is alluring as well as being at the potentially privileged reductive level for psychology. Second, we predicted that participants would be less likely to choose methods from psychology than methods from any of the other sciences, given prior work showing a general skepticism about psychological research.
Third, we predicted that people would be more likely to choose neuroscience as an investigative method for social science phenomena. Even though neuroscience is two levels below the social sciences in the hierarchy, rather than just one, we predicted that people would be attracted to neuroscience methods whenever they were available as a reductive option. Fourth, and conversely, we predicted that participants would be less likely to choose any reductionist methods (chemistry or biology) when asked which methods should be used to investigate a neuroscience phenomenon.
Additionally, we aimed to investigate people’s general preference for reductive explanations, as found in Hopkins et al. (2016), using a method that allowed people to select any method as appropriate for investigating any phenomenon. We particularly wanted to see whether our participants would prefer methods from the field that was immediately below the phenomenon in the hierarchy or whether they might prefer maximally reductive explanations, choosing methods from physics for all phenomena.