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Petruso, E. J., Fuchs, T., & Bingman, V. P. (2007). Time-space learning in homing pigeons (Columba livia): orientation to an artificial light source. Anim. Cogn., 10(2), 181–188.
Abstract: Time-space learning reflects an ability to represent in memory event-stimulus properties together with the place and time of the event; a capacity well developed in birds. Homing pigeons were trained in an indoor octagonal arena to locate one food goal in the morning and a different food goal in the late afternoon. The goals differed with respect to their angular/directional relationship to an artificial light source located outside the arena. Further, the angular difference in reward position approximated the displacement of the sun's azimuth that would occur during the same time period. The experimental birds quickly learned the task, demonstrating the apparent ease with which birds can adopt an artificial light source to discriminate among alternative spatial responses at different times of the day. However, a novel midday probe session following successful learning revealed that the light source was interpreted as a stable landmark and not as a surrogate sun that would support compass orientation. Probe sessions following a phase shift of the light-dark cycle revealed that the mechanism employed to make the temporal discrimination was prevailingly based on an endogenous circadian rhythm and not an interval timing mechanism.
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Chiandetti, C., Regolin, L., Sovrano, V. A., & Vallortigara, G. (2007). Spatial reorientation: the effects of space size on the encoding of landmark and geometry information. Anim. Cogn., 10(2), 159–168.
Abstract: The effects of the size of the environment on animals' spatial reorientation was investigated. Domestic chicks were trained to find food in a corner of either a small or a large rectangular enclosure. A distinctive panel was located at each of the four corners of the enclosures. After removal of the panels, chicks tested in the small enclosure showed better retention of geometrical information than chicks tested in the large enclosure. In contrast, after changing the enclosure from a rectangular-shaped to a square-shaped one, chicks tested in the large enclosure showed better retention of landmark (panels) information than chicks tested in the small enclosure. No differences in the encoding of the overall arrangement of landmarks were apparent when chicks were tested for generalisation in an enclosure differing from that of training in size together with a transformation (affine transformation) that altered the geometric relations between the target and the shape of the environment. These findings suggest that primacy of geometric or landmark information in reorientation tasks depends on the size of the experimental space, likely reflecting a preferential use of the most reliable source of information available during visual exploration of the environment.
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Naug, D., & Arathi, H. S. (2007). Sampling and decision rules used by honey bees in a foraging arena. Anim. Cogn., 10(2), 117–124.
Abstract: Animals must continuously choose among various available options to exploit the most profitable resource. They also need to keep themselves updated about the values of all available options, since their relative values can change quickly due to depletion or exploitation by competitors. While the sampling and decision rules by which foragers profitably exploit a flower patch have attracted a great deal of attention in theory and experiments with bumble bees, similar rules for honey bee foragers, which face similar foraging challenges, are not as well studied. By presenting foragers of the honey bee Apis cerana with choice tests in a foraging arena and recording their behavior, we investigate possible sampling and decision rules that the foragers use to choose one option over another and to track other options. We show that a large part of the sampling and decision-making process of a foraging honey bee can be explained by decomposing the choice behavior into dichotomous decision points and incorporating the cost of sampling. The results suggest that a honey bee forager, by using a few simple rules as part of a Bayesian inference process, is able to effectively deal with the complex task of successfully exploiting foraging patches that consist of dynamic and multiple options.
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Clara, E., Regolin, L., Vallortigara, G., & Rogers, L. (2007). Perception of the stereokinetic illusion by the common marmoset (Callithrix jacchus). Anim. Cogn., 10(2), 135–140.
Abstract: Stereokinetic illusions have never been investigated in non-human primates, nor in other mammalian species. These illusions consist in the perception of a 3D solid object when certain 2D stimuli are rotated slowly in the plane perpendicular to the line of sight. The ability to perceive the stereokinetic illusion was investigated in the common marmoset (Callithrix jacchus). Four adult marmosets were trained to discriminate between a solid cylinder and a solid cone for food reward. Once learning criterion was reached, the marmosets were tested in sets of eight probe trials in which the two solid objects used at training were replaced by two rotating 2D stimuli. Only one of these stimuli produced, at least to the human observer, the stereokinetic illusion corresponding to the solid object previously reinforced. At test, the general behaviour and the total time spent by the marmosets observing each stimulus were recorded. The subjects stayed longer near the stimulus producing the stereokinetic illusion corresponding to the solid object reinforced at training than they did near the illusion corresponding to the previously non-rewarded stimulus. Hence, the common marmosets behaved as if they could perceive stereokinetic illusions.
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Hayashi, M. (2007). Stacking of blocks by chimpanzees: developmental processes and physical understanding. Anim. Cogn., 10(2), 89–103.
Abstract: The stacking-block task has been used to assess cognitive development in both humans and chimpanzees. The present study reports three aspects of stacking behavior in chimpanzees: spontaneous development, acquisition process following training, and physical understanding assessed through a cylindrical-block task. Over 3 years of longitudinal observation of block manipulation, one of three infant chimpanzees spontaneously started to stack up cubic blocks at the age of 2 years and 7 months. The other two infants began stacking up blocks at 3 years and 1 month, although only after the introduction of training by a human tester who rewarded stacking behavior. Cylindrical blocks were then introduced to assess physical understanding in object-object combinations in three infant (aged 3-4) and three adult chimpanzees. The flat surfaces of cylinders are suitable for stacking, while the rounded surface is not. Block manipulation was described using sequential codes and analyzed focusing on failure, cause, and solution in the task. Three of the six subjects (one infant and two adults) stacked up cylindrical blocks efficiently: frequently changing the cylinders' orientation without contacting the round side to other blocks. Rich experience in stacking cubes may facilitate subjects' stacking of novel, cylindrical shapes from the beginning. The other three subjects were less efficient in stacking cylinders and used variable strategies to achieve the goal. Nevertheless, they began to learn the effective way of stacking over the course of testing, after about 15 sessions (75 trials).
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Lacreuse, A., Martin-Malivel, J., Lange, H. S., & Herndon, J. G. (2007). Effects of the menstrual cycle on looking preferences for faces in female rhesus monkeys. Anim. Cogn., 10(2), 105–115.
Abstract: Fluctuations of ovarian hormones across the menstrual cycle influence a variety of social and cognitive behaviors in primates. For example, female rhesus monkeys exhibit heightened interest for males and increased agonistic interactions with other females during periods of high estrogen levels. In the present study, we hypothesized that females' preference for males during periods of high estrogen levels is also expressed at the level of face perception. We tested four intact females on two face-tasks involving neutral portraits of male and female rhesus monkeys, chimpanzees and humans. In the visual preference task (VP), monkeys had to touch a button to view a face image. The image remained on the screen as long as the button was touched, and the duration of pressing was taken as an index of the monkey's looking time for the face stimulus. In the Face-Delayed Recognition Span Test (Face-DRST), monkeys were rewarded for touching the new face in an increasing number of serially presented faces. Monkeys were tested 5 days a week across one menstrual cycle. Blood was collected every other day for analysis of estradiol and progesterone. Two of the four females were cycling at the time of testing. We did not find an influence of the cycle on Face-DRST, likely due to a floor effect. In the VP however, the two cycling individuals looked longer at conspecific male faces than female faces during the peri-ovulatory period of the cycle. Such effects were absent for human and chimpanzee faces and for the two noncycling subjects. These data suggest that ovarian hormones may influence females' preferences for specific faces, with heightened preference for male faces during the peri-ovulatory period of the cycle. Heightened interest for stimuli of significant reproductive relevance during periods of high conception risk may help guide social and sexual behavior in the rhesus monkey.
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Neiworth, J. J., Hassett, J. M., & Sylvester, C. J. (2007). Face processing in humans and new world monkeys: the influence of experiential and ecological factors. Anim. Cogn., 10(2), 125–134.
Abstract: This study tests whether the face-processing system of humans and a nonhuman primate species share characteristics that would allow for early and quick processing of socially salient stimuli: a sensitivity toward conspecific faces, a sensitivity toward highly practiced face stimuli, and an ability to generalize changes in the face that do not suggest a new identity, such as a face differently oriented. The look rates by adult tamarins and humans toward conspecific and other primate faces were examined to determine if these characteristics are shared. A visual paired comparison (VPC) task presented subjects with either a human face, chimpanzee face, tamarin face, or an object as a sample, and then a pair containing the previous stimulus and a novel stimulus was presented. The stimuli were either presented all in an upright orientation, or all in an inverted orientation. The novel stimulus in the pair was either an orientation change of the same face/object or a new example of the same type of face/object, and the stimuli were shown either in an upright orientation or in an inverted orientation. Preference to novelty scores revealed that humans attended most to novel individual human faces, and this effect decreased significantly if the stimuli were inverted. Tamarins showed preferential looking toward novel orientations of previously seen tamarin faces in the upright orientation, but not in an inverted orientation. Similarly, their preference to look longer at novel tamarin and human faces within the pair was reduced significantly with inverted stimuli. The results confirmed prior findings in humans that novel human faces generate more attention in the upright than in the inverted orientation. The monkeys also attended more to faces of conspecifics, but showed an inversion effect to orientation change in tamarin faces and to identity changes in tamarin and human faces. The results indicate configural processing restricted to particular kinds of primate faces by a New World monkey species, with configural processing influenced by life experience (human faces and tamarin faces) and specialized to process orientation changes specific to conspecific faces.
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Kulikova, E. E., Isaeva, A. S., Rotkina, A. S., Manykin, A. A., & Letarov, A. V. (2007). Diversity and dynamics of bacteriophages in horse feces. Microbiology, 76(2), 271–278.
Abstract: The complex cellulolytic microbial community of the horse intestines is a convenient model for studying the ecology of bacteriophages in natural habitats. Unlike the rumen of the ruminants, this community of the equine large intestine is not subjected to digestion. The inner conditions of the horse gut are much more stable in comparison to other mammals, due to the fact that the horse diet remains almost unchanged and the intervals between food consumption and defecation are much shorter than the whole digestive cycle. The results of preliminary analysis of the structure and dynamics of the viral community of horse feces, which combines direct and culture methods, are presented. In horse fecal samples, we detected more than 60 morphologically distinct phage types, the majority of which were present as a single phage particle. This indicates that the community includes no less than several hundreds of phage types. Some phage types dominated and constituted 5-11% of the total particle count each. The most numerous phage type had an unusual morphology: the tails of its members were extremely long (about 700 nm), flexible, and irretractable, while their heads were 100 nm in diameter. Several other phage types with similar but not identical properties were detected. The total coliphage plaque count of the samples taken from three animals revealed significant fluctuations in the phage titers. During the observation time, the maximum titer ranged within four orders of magnitude (10(3)-10(7) plaque forming units (PFU)/g); the minimum titer ranged within two orders of magnitude. The samples contained two to five morphologically distinct and potentially competitive coliphage types, specific to a single Escherichia coli strain.
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Koski, S. E., Koops, K., & Sterck, E. H. M. (2007). Reconciliation, relationship quality, and postconflict anxiety: testing the integrated hypothesis in captive chimpanzees. Am. J. Primatol., 69(2), 158–172.
Abstract: Reconciliation is a conflict resolution mechanism that is common to many gregarious species with individualized societies. Reconciliation repairs the damaged relationship between the opponents and decreases postconflict (PC) anxiety. The “integrated hypothesis” links the quality of the opponents' relationship to PC anxiety, since it proposes that conflicts among partners with high relationship quality will yield high levels of PC anxiety, which in turn will lead to an increased likelihood of reconciliation. We tested the integrated hypothesis in captive chimpanzees (Pan troglodytes) in the Arnhem Zoo, The Netherlands. We applied the standard PC/matched control (MC) method. Our results mostly support the integrated hypothesis, in that more valuable and compatible partners (i.e., males and frequent groomers) reconciled more often than less valuable and weakly compatible partners (i.e., females and infrequent groomers). In addition, PC anxiety was higher after conflicts among males than among females. Emotional arousal thus appears to be a mediator facilitating reconciliation. However, in contrast to the predictions derived from the integrated hypothesis, PC anxiety appeared only in aggressees, and not in aggressors, of conflicts. This suggests that while relationship quality determines PC anxiety, it is dependent on the role of the participants in the conflict.
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Hopkins, W. D., Taglialatela, J. P., & Leavens, D. A. (2007). Chimpanzees differentially produce novel vocalizations to capture the attention of a human. Anim. Behav., 73(2), 281–286.
Abstract: Chimpanzees, Pan troglodytes, produce numerous species-atypical signals when raised in captivity. We examined contextual elements of the use of two of these vocal signals, the `raspberry' and the extended grunt. Our results demonstrate that these vocalizations are not elicited by the presence of food, but instead function as attention-getting signals. These findings reveal a heretofore underappreciated category of animal signals: attention-getting sounds produced in novel environmental circumstances. The invention and use of species-atypical signals, considered in relation to group differences in signalling repertoires in apes in their natural habitats, may index a generative capacity in these hominoid species without obvious corollary in other primate species.
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