[DISCLAIMER: Ideas and statements made in this blog post in no way are intended to insult or disrespect my fellow psychologists.]
In this post, I will discuss psychology’s replicability crisis from a new angle. I want to consider the possibility that confusion regarding what scientific theory is and how theory is developed may have contributed to the replicability crisis in psychology.
Scientific theories are internally consistent sets of principles that are put forward to explain various empirical phenomena. Theories compete in the scientific marketplace by being evaluated according to the following five criteria (Popper, 1959; Quine & Ullian, 1978):
1. parsimony: simpler theories involving the fewest entities are preferred to more complicated theories
2. explanatory power: theories that can explain many empirical phenomena are preferred to theories that can only explain a few phenomena
3. predictive power: a useful theory makes new empirical predictions above and beyond extant theories
4. falsifiability: a theory must yield falsifiable predictions
5. accuracy: degree to which a theory’s empirical predictions match experimental results
It is important to explicitly point out, however, that underlying all of these considerations is the fact that before a theory can be put forward, demonstrably repeatable empirical phenomena need to exist in the first place that need to be explained! Demonstrably repeatable is understood to mean that an empirical phenomenon “can be regularly reproduced by anyone who carries out the appropriate experiment in the way prescribed” (Popper, 1959, p. 23). Put simply, scientific theories aim to explain repeatable empirical phenomena; without repeatable empirical phenomena, there is nothing to explain and hence no theories can be developed.
The idea then is that confusion regarding these points may have contributed to the current replicability crisis. To support my point, I will briefly review some examples from the beleaguered “social priming” literature. [DISCLAIMER: I contend my argument likely also holds in other areas of experimental psychology; I’ve chosen this literature out of convenience, and hence my intention was not to pick on these specific researchers.]
For example, in a piece entitled “The Alleged Crisis and the Illusion of Exact Replication”, Stroebe and Strack (2014) state that:
“Although reproducibility of scientific findings is one of science’s defining features, the ultimate issue is the extent to which a theory has undergone strict tests and has been supported by empirical findings” (p. 60).
Stroebe and Strack seem to be saying that the most important issue (i.e., the “ultimate issue”) in evaluating scientific theory is whether the theory has been supported by empirical findings (accuracy criterion #5 from above), but at the same time downplay the reproducibility of findings as “one of science’s defining features”. This kind of position, however, doesn’t seem to fit with the considerations above whereby reproducible empirical phenomena are required before a scientific theory can even be put forward, let alone be evaluated viz-a-viz other theories.
In another example, Cesario (2014) — in the context of discussing what features of the original methodology need to be duplicated for a replication attempt to be informative — states:
“We know this only because we have relevant theories that tell us that these features should matter.” (p. 42) “Theories inform us as to which variables are important and which are unimportant (i.e., which variables can be modified from one research study to the next without consequence).” (p. 45)
Cesario seems to be saying that we can use a scientific theory to tell us which methodological features in an original study need to be duplicated to reliably observe an empirical phenomenon. Such a position would seem to be putting the cart in front of the horse, however, given that without demonstrably repeatable empirical phenomena to explain, no theory can be developed in the first place.1
A final example comes from an article by Dijksterhuis (2014, “Welcome back theory!”), who summarizes Cesario’s (2014) paper by saying:
“Cesario draws the conclusion that although behavioral priming researchers could show more methodological rigor, the relative infancy of the theory is the main reason the field faces a problem.” (p. 74)
Dijksterhuis seems to be saying that the field of behavioral priming currently has problems with non-replications because of insufficiently developed theory. This position is again difficult to reconcile with the standard conceptualization of scientific theory. With all due respect, such a position would be akin to saying that ESP researchers have yet to document replicable ESP findings because theories of ESP are insufficiently developed!
But how could this happen?
I contend that such confusion regarding scientific theory has emerged due (at least in part) to the relatively weak methods used in modal research (LeBel & Peters, 2011). This includes the improper use of null hypothesis significant testing (i.e., p<.05 indicates a “reliable” finding) and an over-emphasis on conceptual rather than direct replications. Conceptual replications involve immediately following up an observed effect with a study using a different methodology, hence rendering any negative results completely ambiguous (i.e., was the different result due to the different methodology or due to the falsity of the tested hypothesis). This practice effectively shields any positive empirical findings from falsification (see here for a great blog post precisely on this point; see also Greenwald et al., 1986). Granted, once the reproducibility of a particular effect has been independently confirmed (using the original methodology), it is of course important to subsequently test whether the effect generalizes to other methods (i.e., other operationalizations of the IV and DV). However, we simply cannot skip the first step. This broadly fits with Rozin’s (2001) position that psychologists need to place much more emphasis on first reliably describing empirical phenomena, before we set out to actually test hypotheses about those phenomena.
1. That being said, Cesario should be lauded for his public stance that behavioral priming researchers need to directly replicate their own findings (using the same methodology) before publishing their findings.
Cesario, J. (2014). Priming, replication, and the hardest science. Perspectives on Psychological Science, 9, 40–48.
Dijksterhuis, A. (2014). Welcome Back Theory!. Perspectives on Psychological Science, 9(1), 72-75.
Greenwald, A. G., Pratkanis, A. R., Leippe, M. R., & Baumgardner, M. H. (1986). Under what conditions does theory obstruct research progress?. Psychological Review, 93(2), 216.
LeBel, E. P., & Peters, K. R. (2011). Fearing the future of empirical psychology: Bem’s (2011) evidence of psi as a case study of deficiencies in modal research practice. Review of General Psychology, 15,371-379
Popper, K. R. (1959). The logic of scientific discovery. New York, NY: Basic Books
Quine, W. V. O., & Ullian, J. S. (1978). The web of belief (2nd ed.). New York, NY: Random House
Rozin, P. (2001). Social psychology and science: Some lessons from Solomon Asch. Personality and Social Psychology Review, 5(1), 2-14.
Stroebe, W., & Strack, F. (2014). The alleged crisis and the illusion of exact replication. Perspectives on Psychological Science, 9, 59–71.