Vasconcelos, M., Urcuioli, P.J. & Lionello-Denolf, K.M. (2007).
Failure to replicate the “work ethic” effect in pigeons.
Journal of the Experimental Analysis of Behavior, 87, 383-399.
We report six unsuccessful attempts to replicate the “work ethic” phenomenon reported by Clement, Feltus,
Kaiser, and Zentall (2000). In Experiments 1 - 5, pigeons learned two simultaneous discriminations in which
the S+ and S– stimuli were obtained by pecking an initial stimulus once or multiple (20 or 40) times.
Subsequent preference tests between the S+ stimuli and between the S– stimuli mostly revealed indifference,
on average, between the S+ from the multiple-peck (high-effort) trials and the S+ from the one-peck (low-effort)
trials, and likewise between the two respective S– stimuli. Using a slightly different procedure that
permitted assessment of the relative aversiveness of low versus high effort, Experiment 6 again revealed a
pattern of indifference despite showing that pigeons took considerably longer to begin pecking on high- than
on low-effort trials. Our findings call into question the reliability of the original findings and the
sufficiency of the hypothesized within-trial contrast mechanism to produce them.
Key words: work ethic, stimulus value, simultaneous discrimination, within-trial contrast, delay-reduction hypothesis, key peck, pigeons