human rationalityThis is the second in a two-part discussion about human rationality. Click to read Part 1, Are We Rational Animals?.

Intelligence as a predictor of rationality

Some may be surprised to learn that high levels of intelligence do not necessarily indicate high levels of rationality.  In fact, some people may rank high in intelligence while low in rationality.  There is more to sound thinking than intelligence.

Below is a list of rational thinking tasks and their association with cognitive ability/intelligence from Stanovich (2010, p.221).

Tasks that fail to show associations with cognitive ability

  • Noncausal base-rate usage (Stanovich & West, 1998c, 1999, 2008)
  • Conjunction fallacy between subjects (Stanovich & West, 2008)
  • Framing between subjects (Stanovich & West, 2008)
  • Anchoring effect (Stanovich & West, 2008)
  • Evaluability less is more effect (Stanovich & West, 2008)
  • Proportion dominance effect (Stanovich & West, 2008)
  • Sunk cost effect (Stanovich & West, 2008; Parker & Fischhoff, 2005)
  • Risk/benefit confounding (Stanovich & West, 2008)
  • Omission bias (Stanovich & West, 2008)
  • Perspective bias (Stanovich & West, 2008)
  • Certainty effect (Stanovich & West, 2008)
  • WTP/WTA difference (Stanovich & West, 2008)
  • My-side bias between and within S (Stanovich & West, 2007, 2008)
  • Newcomb’s problem (Stanovich & West, 1999; Toplak & Stanovich, 2002)

Tasks that show some associations with cognitive ability

  • Causal base-rate usage (Stanovich & West, 1998c, 1998d)
  • Outcome bias (Stanovich & West, 1998c, 2008)
  • Framing within subjects (Frederick, 2005; Parker & Fischhoff, 2005; Stanovich & West, 1998b, 1999)
  • Denominator neglect (Stanovich & West, 2008; Kokis et al., 2002)
  • Probability matching (Stanovich & West, 2008; West & Stanovich, 2003)
  • Hindsight bias (Stanovich & West, 1998c)
  • Ignoring P(D/NH) (Stanovich & West, 1998d, 1999)
  • Covariation detection (Stanovich & West, 1998c, 1998d; Sá et al., 1999)
  • Belief bias in syllogistic reasoning (Stanovich & West, 1998c, 2008)
  • Belief bias in modus ponens (Stanovich & West, 2008)
  • Informal argument evaluation (Stanovich & West, 1997, 2008)
  • Four-card selection task (Stanovich & West, 1998a, 2008)
  • EV maximization in gambles (Frederick, 2005; Benjamin & Shapiro, 2005)

Rationality is a multi-dimensional concept and it can be assessed by the use of numerous rationality tasks.  The Stanovich Research Lab suggests the need for RQ tests (rationality quotient) tests.  Rationality is probably more malleable than intelligence and just as important, if not more important.

Rationality requires three different classes of mental characteristic

“First, algorithmic-level cognitive capacity is needed in order that override and simulation activities can be sustained. Second, the reflective mind must be characterized by the tendency to initiate the override of suboptimal responses generated by the autonomous mind and to initiate simulation activities that will result in a better response. Finally, the mindware that allows the computation of rational responses needs to be available and accessible during simulation activities.  Intelligence tests assess only the first of these three characteristics that determine rational thought and action. As measures of rational thinking, they are radically incomplete” (Stanovich, 2010, pp.217-218).

Implications of Research and Future Research on Rationality

When asked to define rationality, the lay public will provide answers that vary substantially.  Just as when people try to describe intelligence, the definitions are so ambiguous they can be interpreted to mean virtually anything.  Cognitive science offers a definition of rationality that differs from the definition of intelligence.  As I have shown in this paper, many rational thinking tasks can be assessed and a fair amount of data has shown it is not unusual for intelligence and rationality to be dissociated.  It is a mistake to label rationality as just another form of intelligence.  This furthers the problem of associating all sound thinking qualities with intelligence.  Intelligence and rationality are vastly different and should differentiated.

Preliminary indicators have shown that rationality may be more malleable than intelligence.  In an effort to foster rational thinking skills it is important to acquire specialized mindware.  There is no reason this mindware should not be presented to students.  In order to promote learning of the mindware necessary for rational thinking, educators need to become familiar with what is needed for rational thinking and be able to properly define this concept.

Irrationality is often due to mindware gaps.  Knowledge in the domains of scientific thinking, probabilistic thinking, and logic decrease irrationality tendencies.

The ability to override the autonomous mind is often negated when proper mindware is not available.  Learned mindware alleviates the problem.  Fully disjunctive reasoning, the tendency to consider all possible states of the world when deciding among options or when choosing a problem solution in a reasoning task, is a rational thinking strategy that can be taught (Reyna & Farley, 2006).  The teaching of considering alternative hypotheses is a relatively easy strategy that promotes rational thinking.   To promote the idea the simple instruction, “think of the opposite,” is given. Studies have demonstrated this strategy can help prevent the occurrence of various thinking errors (Sanna & Schwartz, 2006).  Probabilistic thinking has been shown to be more difficult to teach than the previously mentioned strategies, yet still teachable (Stanovich, 2009).  Causal reasoning, an important element in achieving rationality is teachable.

Acquiring specialized mindware is needed for rational thinking, but avoiding contaminated mindware is also important.  “[T]he principle of falsifiability provides a wonderful inoculation against many kinds of nonfunctional beliefs” (Stanovich, 2009).  The principle is taught in many low-level methodology courses and should be taught to high school students.  Many pseudoscientific claims can be dismissed when applying the falsifiability principle.


Reyna, V.F., & Farley, F. (2006).  Risk and rationality in adolescent decision making.  Psychological Science in the Public Interest, 7, 1-44.

Sanna, L.J., & Schwartz, N. (2006).  Metacognitive experiences and human judgment: The case of hindsight bias and its debiasing.  Current Directions in Psychological Science, 15, 172-176.

Stanovich, K. E. (2009). What intelligence tests miss: The psychology of rational thought. New Haven, CT: Yale University Press.

Stanovich, K. E., & Stanovich, P. J. (2010).  A framework for critical thinking, rational thinking, and intelligence. In D. Preiss & R. J. Sternberg (Eds.), Innovations in educational psychology: Perspectives on learning, teaching and human development (pp. 195-237).  New York: Springer.

Photo by Sweeney Art Gallery, avialable under a Creative Commons attribution license.



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    Last reviewed: By John M. Grohol, Psy.D. on 12 Feb 2011
    Published on All rights reserved.

APA Reference
Hale, J. (2011). Are We Rational Animals? Part 2. Psych Central. Retrieved on March 2, 2015, from


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