Recent Research
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Imitation and emulation by dogs using a bidirectional control procedure.
Holly C. Miller, Rebecca Rayburn-Reeves, Thomas R. Zentall
A successful procedure for studying imitative behavior in non-humans is the bidirectional control procedure in which observers are exposed to a demonstrator that responds by moving a manipulandum in one of two different directions (e.g., left vs. right). Imitative learning is demonstrated when observers make the response in the direction that they observed it being made. This procedure controls for socially mediated effects (the mere presence of a demonstrator), stimulus enhancement (attention drawn to a manipulandum by its movement), and if an appropriate control is included, emulation (learning how the environment works). Recent research with dogs has found that dogs may not demonstrate imitative learning when the demonstrator is human
Read Entire ArticleObject permanence in dogs: Invisible displacement in a rotation task
Holly C. Miller, Cassie D. Gipson, Aubrey Vaughan, Rebecca Rayburn-Reeves, and Thomas R. Zentall
Dogs were tested for object permanence using an invisible displacement in which an object was hidden in one of two containers at either end of a beam and the beam was rotated. Consistent with earlier research, when the beam was rotated 180º, the dogs failed to find the object. However, when the beam was rotated only 90º, they were successful. Furthermore, when the dogs were led either 90º or 180º around the apparatus, they were also successful. In a control condition, when the dogs could not see the direction of the 90º rotation, they failed to find the object...
Read Entire ArticleEpisodic-like memory: Pigeons can report location pecked when unexpectedly asked
Thomas R. Zentalla, Rebecca A. Singer, Jessica P. Stagner
Pigeons were tested for their ability to report the location they recently pecked, without prior experience having to do so. Theywere first pretrained to report the location that they had just pecked. Theywere then trained on a conditional discrimination to associate yellow and blue samples with vertical and horizontal comparisons, respectively, independent of comparison location. On probe trials in testing, when after choosing a vertical or horizontal line following the yellowor blue sample, the pigeonswere ‘asked’ which location they had just pecked, they showed a significant tendency to choose correctly in spite of the fact that location of the correct comparisonwas incidental to the task...
Read Entire ArticlePreference for rewards that follow greater effort and greater delay.
Thomas R. Zentall, Jérôme Alessandri, Jean-Claude Darcheville, and Yvonne Delevoye-Turrell
Humans prefer (conditioned) rewards that follow greater effort (Aronson & Mills, 1959). This phenomenon can be interpreted as evidence for cognitive dissonance (or as justification of effort) but may also result from (1) the contrast between the relatively greater effort and the signal for reinforcement or (2) the delay reduction signaled by the conditioned reinforcer. In the present study, we examined the effect of prior force and prior time to produce stimuli associated with equal reinforcement. As expected, pressing with greater force or for a longer time was less preferred than pressing with less force or for a shorter time. However, participants preferred the conditioned reinforcer that followed greater force and more time...
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