Navarro, A. D. & Fantino, E. (2005).
The sunk cost effect in pigeons and humans.
Journal of the Experimental Analysis of Behavior, 83, 1-13.
The sunk cost effect is the increased tendency to persist in an endeavor once
an investment of money, effort, or time has been made. To date, humans are
the only animal in which this effect has been observed unambiguously. We
developed a behavior-analytic model of the sunk cost effect to explore the
potential for this behavior in pigeons as well as in humans. Each trial
started out with a short expected ratio, but on some trials assumed a longer
expected ratio part way through the trial. Subjects had the (usually
preferable) option of “escaping” the trial if the longer expected
ratio had come into effect in order to bring on a new trial that again had
a short expected ratio. In Experiments 1 through 3, we manipulated two
independent variables that we hypothesized would affect the pigeons’
ability to discriminate the increase in the expected ratio within a trial:
(a) the presence or absence of stimuli that signal an increase in the
expected ratio, and (b) the severity of the increase in the expected
ratio. We found that the pigeons were most likely to persist nonoptimally
through the longer expected ratios when stimulus changes were absent and
when the increase in the expected ratio was less severe. Experiment 4
employed a similar procedure with human subjects that manipulated only
the severity of the increase in the expected ratio and found a result
similar to that of the pigeon experiment. In Experiment 5, we tested
the hypothesis that a particular history of reinforcement would induce
pigeons to persist through the longer expected ratios; the results
suggested instead that the history of reinforcement caused the pigeons
to persist less compared to pigeons that did not have that history.
Key words: sunk cost, Concorde fallacy, escalation, choice, diminishing
returns, discriminative stimuli, pigeons