Soproni, K., Miklósi, A., Topál, J., & Csányi, V. (2001). Comprehension of human communicative signs in pet dogs (Canis familiaris). J Comp Psychol, 115(2), 122–126.
Abstract: On the basis of a study by D. J. Povinelli, D. T. Bierschwale, and C. G. Cech (1999), the performance of family dogs (Canis familiaris) was examined in a 2-way food choice task in which 4 types of directional cues were given by the experimenter: pointing and gazing, head-nodding (“at target”), head turning above the correct container (“above target”), and glancing only (“eyes only”). The results showed that the performance of the dogs resembled more closely that of the children in D. J. Povinelli et al.'s study, in contrast to the chimpanzees' performance in the same study. It seems that dogs, like children, interpret the test situation as being a form of communication. The hypothesis is that this similarity is attributable to the social experience and acquired social routines in dogs because they spend more time in close contact with humans than apes do, and as a result dogs are probably more experienced in the recognition of human gestures.
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Zentall, T. R., Klein, E. D., & Singer, R. A. (2004). Evidence for detection of one duration sample and default responding to other duration samples by pigeons may result from an artifact of retention-test ambiguity. J Exp Psychol Anim Behav Process, 30(2), 129–134.
Abstract: S. C. Gaitan and J. T. Wixted (2000) proposed that when pigeons are trained on a conditional discrimination to associate 1 duration sample with 1 comparison and 2 other duration samples with a 2nd comparison, they detect only the single duration, and on trials involving either of the 2 other duration samples, they respond to the other comparison by default. In 2 experiments, the authors show instead that pigeons lend to treat the retention intervals (such as those used by Gaitan and Wixted) as intertrial intervals, and thus, they tend to treat all trials with a delay as 0-s sample trials. The authors tested this hypothesis by showing that divergent retention functions do not appear when the retention interval is discriminably different from the intertrial interval.
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Urcuioli, P. J., DeMarse, T. B., & Zentall, T. R. (1998). Transfer across delayed discriminations: II. Differences in the substitutability of initial versus test stimuli. J Exp Psychol Anim Behav Process, 24(1), 47–59.
Abstract: In 2 experiments, pigeons were trained on, and then transferred to, delayed simple discriminations in which the initial stimuli signalled reinforcement versus extinction following a retention interval. Experiment 1 showed that discriminative responding on the retention test transferred to novel test stimuli that had appeared in another delayed simple discrimination but not to stimuli having the same reinforcement history off-baseline. By contrast, Experiment 2 showed that performances transferred to novel initial stimuli whether they had been trained on-baseline or off-baseline. These results suggest that the test stimuli in delayed simple discriminations acquire control over responding only in the memory task itself. On the other hand, control by the initial stimuli, if coded as outcome expectancies, does not require such task-specific training.
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Zentall, T. R., & Sherburne, L. M. (1994). Transfer of value from S+ to S- in a simultaneous discrimination. J Exp Psychol Anim Behav Process, 20(2), 176–183.
Abstract: Value transfer theory has been proposed to account for transitive inference effects (L. V. Fersen, C. D. L. Wynne, J. D. Delius, & J. E. R. Staddon, 1991), in which following training on 4 simultaneous discriminations (A+B-, B+C-, C+D-, D+E-) pigeons show a preference for B over D. According to this theory, some of the value of reinforcement acquired by each S+ transfers to the S-. In the transitive inference experiment, C (associated with both reward and nonreward) can transfer less value to D than A (associated only with reward) can transfer to B. Support for value transfer theory was demonstrated in 2 experiments in which an S- presented in the context of a stimulus to which responses were always reinforced (S+) was preferred over an S- presented in the context of a stimulus to which responses were sometimes reinforced (S +/-).
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Urcuioli, P. J., & Zentall, T. R. (1992). Transfer across delayed discriminations: evidence regarding the nature of prospective working memory. J Exp Psychol Anim Behav Process, 18(2), 154–173.
Abstract: Pigeons were trained successively either on 2 delayed simple discriminations or on a delayed simple discrimination followed by delayed matching-to-sample. During subsequent transfer tests, the initial stimuli from the 1st task were substituted for those in the 2nd. Performances transferred immediately if both sets of initial stimuli had been associated with the presence versus absence of food on their respective retention tests, and the direction of transfer (positive or negative) depended on whether the substitution involved stimuli with identical or different outcome associates. No transfer was found, however, when the initial stimuli were associated with different patterns of responding but food occurred at the end of every trial. These results are consistent with outcome expectancy mediation but are incompatible with response intention and retrospective coding accounts.
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Urcuioli, P. J., & Zentall, T. R. (1986). Retrospective coding in pigeons' delayed matching-to-sample. J Exp Psychol Anim Behav Process, 12(1), 69–77.
Abstract: In this study we examined how coding processes in pigeons' delayed matching-to-sample were affected by the stimuli to be remembered. In Experiment 1, two groups of pigeons initially learned 0-delay matching-to-sample with identical comparison stimuli (vertical and horizontal lines) but with different sample stimuli (red and green hues or vertical and horizontal lines). Longer delays were then introduced between sample offset and comparison onset to assess whether pigeons were prospectively coding the same events (viz., the correct line comparisons) or retrospectively coding different events (viz., their respective sample stimuli). The hue-sample group matched more accurately and showed a slower rate of forgetting than the line-sample group. In Experiment 2, pigeons were trained with either hues or lines as both sample and comparison stimuli, or with hue samples and line comparisons or vice versa. Subsequent delay tests revealed that the hue-sample groups remembered more accurately and generally showed slower rates of forgetting than the line-sample groups. Comparison dimension had little or no effect on performance. Together, these data suggest that pigeons retrospectively code the samples in delayed matching-to-sample.
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Aust, U., & Huber, L. (2006). Picture-object recognition in pigeons: evidence of representational insight in a visual categorization task using a complementary information procedure. J Exp Psychol Anim Behav Process, 32(2), 190–195.
Abstract: Success in tasks requiring categorization of pictorial stimuli does not prove that a subject understands what the pictures stand for. The ability to achieve representational insight is by no means a trivial one because it exceeds mere detection of 2-D features present in both the pictorial images and their referents. So far, evidence for such an ability in nonhuman species is weak and inconclusive. Here, the authors report evidence of representational insight in pigeons. After being trained on pictures of incomplete human figures, the birds responded significantly more to pictures of the previously missing parts than to nonrepresentative stimuli, which demonstrates that they actually recognized the pictures' representational content.
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Washburn, D. A., Smith, J. D., & Shields, W. E. (2006). Rhesus monkeys (Macaca mulatta) immediately generalize the uncertain response. J Exp Psychol Anim Behav Process, 32(2), 185–189.
Abstract: Rhesus monkeys (Macaca mulatta) have learned, like humans, to use an uncertain response adaptively under test conditions that create uncertainty, suggesting a metacognitive process by which human and nonhuman primates may monitor their confidence and alter their behavior accordingly. In this study, 4 rhesus monkeys generalized their use of the uncertain response, without additional training, to 2 familiar tasks (2-choice discrimination learning and mirror-image matching to sample) that predictably and demonstrably produce uncertainty. The monkeys were significantly less likely to use the uncertain response on trials in which the answer might be known. These results indicate that monkeys, like humans, know when they do not know and that they can learn to use a symbol as a generalized means for indicating their uncertainty.
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Brannon, E. M., Cantlon, J. F., & Terrace, H. S. (2006). The role of reference points in ordinal numerical comparisons by rhesus macaques (Macaca mulatta). J Exp Psychol Anim Behav Process, 32(2), 120–134.
Abstract: Two experiments examined ordinal numerical knowledge in rhesus macaques (Macaca mulatta). Experiment 1 replicated the finding (E. M. Brannon & H. S. Terrace, 2000) that monkeys trained to respond in descending numerical order (4-->3-->2-->1) did not generalize the descending rule to the novel values 5-9 in contrast to monkeys trained to respond in ascending order. Experiment 2 examined whether the failure to generalize a descending rule was due to the direction of the training sequence or to the specific values used in the training sequence. Results implicated 3 factors that characterize a monkey's numerical comparison process: Weber's law, knowledge of ordinal direction, and a comparison of each value in a test pair with the reference point established by the first value of the training sequence.
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Beran, M. J., Smith, J. D., Redford, J. S., & Washburn, D. A. (2006). Rhesus macaques (Macaca mulatta) monitor uncertainty during numerosity judgments. J Exp Psychol Anim Behav Process, 32(2), 111–119.
Abstract: Two rhesus macaques (Macaca mulatta) judged arrays of dots on a computer screen as having more or fewer dots than a center value that was never presented in trials. After learning a center value, monkeys were given an uncertainty response that let them decline to make the numerosity judgment on that trial. Across center values (3-7), errors occurred most often for sets adjacent in numerosity to the center value. The monkeys also used the uncertainty response most frequently on these difficult trials. A 2nd experiment showed that monkeys' responses reflected numerical magnitude and not the surface-area illumination of the displays. This research shows that monkeys' uncertainty-monitoring capacity extends to the domain of numerical cognition. It also shows monkeys' use of the purest uncertainty response possible, uncontaminated by any secondary motivator.
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