In the psychological literature logical reasoning is
associated with System 2 processes
(characterized as slow, controlled, limited in
capacity, and effortful) whereas belief based
judgments are frequently linked to System 1
processes (described as fast, automatic, high in
capacity, and effortless). This dichotomization of
cognitive processes forms the basis for a variety
of dual process models in cognitive science (i.e.,
Kahneman, 2002). Here we focus on the default-
interventionist account (DI account; Evans, 2007)
which postulate that these processes operate in
a sequential fashion.
We investigated the effects of ego depletion on
hypothetical syllogistic reasoning by
manipulating self regulatory resources between
groups. Participants were subsequently
instructed to evaluate conclusions of syllogisms
either on the basis of their semantic believability
or logical validity.
We hypothesized that belief based judgments
would be faster and more accurate relative to
logic judgments and that
ego-depletion would interfere with the latter but
not with the former. This hypothesis was
motivated by the strength model of self-control
(Baumeister et al., 2007) and
the default-interventionist account of reasoning
(Evans, 2007).
Our experiment did not support the predictions.
Statistical analysis showed that:
• logic based judgments were faster compared to
belief based judgments (Figure 1).
• ego depleted participants performed more
accurate relative to controls (Figure 2).
The statistical results provide a replication of the
observations made by Handley et al. (2011) and
implicate that logical reasoning precedes belief
based reasoning, which stands in direct contrast
with the predictions
derived from the DI model (Evans, 2007).
In our view the dichotomous DI account draws
an oversimplified picture which leaves no room
for any gray shadings between Type 1 and Type 2
processes. It seem more plausible that the
transitions between Type 1 and Type 2 processes
are gradual and that these processes constantly
interact and never reside in absolute stasis.
• Baumeister, R. F., Vohs, K. D., & Tice, D. M. (2007). The strength model of self-
control. Current Directions in Psychological Science, 16(6), 351-355.
• Evans, J. S. B. T. (2007). On the resolution of conflict in dual process theories of
reasoning. Thinking & Reasoning, 13(4), 321-339.
• Kahneman, D. (2002). Nobel Prize lecture by Daniel Kahneman. [Video file].
Available from:
http:// nobelprize.org/mediaplayer/index.php?id=531
• Handley, S. J., Newstead, S. E., & Trippas, D. (2011). Logic, beliefs, and
instruction: a test of the default interventionist account of belief bias. Journal of
Experimental Psychology: Learning, Memory, and Cognition, 37(1), 28-43.
Figure 1. Reaction time as a function of instruction.
The effects of ego depletion on belief bias
Christopher Germann - christopher.germann@plymouth.ac.uk
Figure 2. Accuracy as a function of ego depletion condition
and problem type.
Type 1 Type 2 Response