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Voelkl, B., & Huber, L. (2007). Common marmosets (Callithrix jacchus) do not utilize social information in three simultaneous social foraging tasks. Anim. Cogn., 10(2), 149–158.
Abstract: Abstract Social foraging is suggested to increase foraging efficiency, as individuals might benefit from public information acquired by monitoring the foraging activities of other group members. We conducted a series experiments with captive common marmosets (Callithrix jacchus) to investigate to what extent marmosets utilize social information about food location when foraging simultaneously with conspecifics. Subjects were confronted with dominant and subordinate demonstrators in three experiments which differed in the amount of information about food location available to the demonstrators. In all three experiments, the focal subjects` performance in the social condition was not enhanced in comparison to a non-social control condition. Because we could rule out kleptoparasitism and aggressive displacements as explanations, we argue that the subjects tendency for scramble competition by avoiding others and dispersing over the foraging area seems to inhibit or mask the acquisition of social information about the location of rewarded patches.
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Fortes, A. F., Merchant, H., & Georgopoulos, A. P. (2004). Comparative and categorical spatial judgments in the monkey: “high” and “low”. Anim. Cogn., 7(2), 101–108.
Abstract: Adult human subjects can classify the height of an object as belonging to either of the “high” or “low” categories by utilizing an abstract concept of midline that divides the vertical dimension into two halves. Children lack this abstract concept of midline, do not have a sense that these categories are directional opposites, and their categorical and comparative usages of high(er) or low(er) are restricted to the corresponding poles. We investigated the abilities of a rhesus monkey to perform categorical judgments in space. We were also interested in the presence of the congruity effect (a decrease in response time when the objects compared are closer to the category pole) in the monkey. The presence of this phenomenon in the monkey would allow us to relate the behavior of the animal to the two major competing hypotheses that have been suggested to explain the congruity effect in humans: the analog and semantic models. The monkey was trained in delayed match-to-sample tasks in which it had to categorize objects as belonging to either a high or low category. The monkey was able to generate an abstract notion of midline in a fashion similar to that of adult human subjects. The congruity effect was also present in the monkey. These findings, taken together with the notion that monkeys are not considered to think in propositional terms, may favor an analog comparison model in the monkey.
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Kitchen, D., Bergman, T., Cheney, D., Nicholson, J., & Seyfarth, R. (2010). Comparing responses of four ungulate species to playbacks of baboon alarm calls. Anim. Cogn., 13(6), 861–870.
Abstract: A growing body of evidence suggests that a wide range of animals can recognize and respond appropriately to calls produced by other species. Social learning has been implicated as a possible mechanism by which heterospecific call recognition might develop. To examine whether familiarity and/or shared vulnerability with the calling species might influence the ability of sympatric species to distinguish heterospecific alarm calls, we tested whether four ungulate species (impala: Aepyceros melampus; tsessebe: Damaliscus lunatus; zebra: Equus burchelli; wildebeest: Connochaetes taurinus) could distinguish baboon (Papio hamadryas ursinus) alarm calls from other loud baboon calls produced during intra-specific aggressive interactions (‘contest’ calls). Overall, subjects’ responses were stronger following playback of alarm calls than contest calls. Of the species tested, impala showed the strongest responses and the greatest difference in composite response scores, suggesting they were best able to differentiate call types. Compared with the other ungulate species, impala are the most frequent associates of baboons. Moreover, like baboons, they are susceptible to both lion and leopard attacks, whereas leopards rarely take the larger ungulates. Although it seems possible that high rates of association and/or shared vulnerability may influence impala’s greater ability to distinguish among baboon call types, our results point to a stronger influence of familiarity. Ours is the first study to compare such abilities among several community members with variable natural histories, and we discuss future experiments that would more systematically examine development of these skills in young ungulates.
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Maros, K., Gácsi, M., & Miklósi, Á. (2008). Comprehension of human pointing gestures in horses ( Equus caballus ). Anim. Cogn., 11(3), 457–466.
Abstract: Abstract Twenty domestic horses (Equus caballus) were tested for their ability to rely on different human gesticular cues in a two-way object choice task. An experimenter hid food under one of two bowls and after baiting, indicated the location of the food to the subjects by using one of four different cues. Horses could locate the hidden reward on the basis of the distal dynamic-sustained, proximal momentary and proximal dynamic-sustained pointing gestures but failed to perform above chance level when the experimenter performed a distal momentary pointing gesture. The results revealed that horses could rely spontaneously on those cues that could have a stimulus or local enhancement effect, but the possible comprehension of the distal momentary pointing remained unclear. The results are discussed with reference to the involvement of various factors such as predisposition to read human visual cues, the effect of domestication and extensive social experience and the nature of the gesture used by the experimenter in comparative investigations.
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McGonigle, B., Chalmers, M., & Dickinson, A. (2003). Concurrent disjoint and reciprocal classification by Cebus apella in seriation tasks: evidence for hierarchical organization. Anim. Cogn., 6(3), 185–197.
Abstract: We report the results of a 4-year-long study of capuchin monkeys ( Cebus apella ) on concurrent three-way classification and linear size seriation tasks using explicit ordering procedures, requiring subjects to select icons displayed on touch screens rather than manipulate and sort actual objects into groups. The results indicate that C. apella is competent to classify nine items concurrently, first into three disjoint classes where class exemplars are identical to one another, then into three reciprocal classes which share common exemplar (size) features. In the final phase we compare the relative efficiency of executive control under conditions where both hierarchical and/or linear organization can be utilized. Whilst this shows a superiority of categorical based size seriation for a nine item test set suggesting an adaptive advantage for hierarchical over linear organization, Cebus nevertheless achieved high levels of principled linear size seriation with sequence lengths not normally achieved by children below the age of six years.
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Zentall, T. R. (2005). Configural/holistic processing or differential element versus compound similarity. Anim. Cogn., 8(2), 141–142.
Abstract: Before accepting a configural or holistic account of visual perception, one should be sure that an analytic (elemental) account does not provide an equal or better explanation of the results. I suggest that when one forms a compound of a color and a line orientation with one element previously trained as an S+ and the other as an S-, the resulting transfer found will depend on the relative salience of the two elements, and most important, the similarity of the compound to each of the training stimuli. Thus, if a line orientation is placed on a colored background (a separable compound), it will appear more like the colored field used in training, and color will control responding. However, if the line itself is colored (an integral compound), the compound will appear more like the line used in training, and line orientation will control responding. Not only does this account do a better job of explaining the data but it is simpler and it is testable.
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Moskat, C., & Hauber, M. E. (2007). Conflict between egg recognition and egg rejection decisions in common cuckoo (Cuculus canorus) hosts. Anim. Cogn., .
Abstract: Common cuckoos (Cuculus canorus) are obligate brood parasites, laying eggs into nests of small songbirds. The cuckoo hatchling evicts all eggs and young from a nest, eliminating hosts' breeding success. Despite the consistently high costs of parasitism by common cuckoos, great reed warbler (Acrocephalus arundinaceus) hosts sometime accept and other times reject parasitic eggs. To explore the cognitive basis of this seemingly maladaptive variation in host responses, we documented differences in egg rejection rates within 1-day periods just before and during the egg-laying cycle across host nests. Hosts rejected cuckoo eggs at 28% of nests during the pre-egg-laying stage, but when cuckoos exchanged the first host egg with the parasite egg, rejections increased to 75%. Even later, when several host eggs remained in a nest after parasitism, rejection rate fell to 37.5%. Experimental parasitism with conspecific eggs on the first and second day of host laying showed a similar directional change in relative rejection rates, dropping from 35 to 0%. Mistakes in egg discrimination (ejection error and ejection cost) were observed mostly in the latter part of the laying cycle, mainly when nests contained 5-6 eggs. These correlational and experimental patterns of egg rejection support a cognitive process of egg discrimination through several shifts in hosts' optimal acceptance thresholds of foreign eggs. The results are also consistent with the evolution of foreign egg rejection in the context of nest-sanitation (i.e. the removal of foreign objects). Our results suggest that common cuckoo hosts may recognize more eggs than they reject. This implies that the experience of the host with one or more of its own eggs in the clutch is a key factor in rejecting parasite eggs by allowing inspection and learning about their own clutch.
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Punzo, F., & Ludwig, L. (2002). Contact with maternal parent and siblings affects hunting behavior, learning, and central nervous system development in spiderlings of Hogna carolinensis (Araeneae: Lycosidae). Anim. Cogn., 5(2), 63–70.
Abstract: The purpose of this study was to determine the effects of early experience (rearing conditions) on the central nervous system (CNS) and behavior of spiderlings of Hogna carolinensis (Lycosidae). We were interested in whether or not spiderlings that were allowed to remain in contact with their maternal parent and siblings (enriched condition, EC) would exhibit differences in CNS development or subsequent behavior when compared with those reared in isolation (improverished condition, IC). Spiderlings emerged from their egg sacs and climbed onto the dorsal surface of their mother's abdomen where they remained until their yolk supply was depleted (5 days). They dispersed on day 6 after emergence. We compared the ability of 16-day-old EC and IC spiderlings to capture prey in a linear runway and to learn a complex maze (spatial learning). We also compared certain aspects of CNS development (brain weight, total number of brain cells, volume of central body and protocerebral neuropil) in EC and IC spiderlings. Results indicated that EC subjects are more efficient at capturing moving prey (crickets) and exhibited improved performance (significantly fewer blind alley errors) in the maze. The volume of the protocerebral neuropil in 6-day-old EC animals increased 30% over a 5-day period after emergence as compared to IC animals of the same age. The volume of the central body of EC animals increased 34.8% over the same time period. On day 6 after emergence, the weight of the protocerebrum was significantly greater in EC versus IC subjects. There were no significant effects of rearing condition (EC vs IC) or age (1- and 6-day-old spiderlings) on the total number of nerve cells in the protocerebrum, suggesting that the difference in protocerebral weight was due primarily to differences in supporting glial tissues and neuropil matrix. In conclusion, the data suggest that early contact with the maternal parent and siblings is of vital importance to CNS development in lycosid spiderlings and can influence the capacity for spatial learning as well as the ability to capture prey.
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Call, J., Carpenter, M., & Tomasello, M. (2005). Copying results and copying actions in the process of social learning: chimpanzees (Pan troglodytes) and human children (Homo sapiens). Anim. Cogn., 8(3), 151–163.
Abstract: There is currently much debate about the nature of social learning in chimpanzees. The main question is whether they can copy others' actions, as opposed to reproducing the environmental effects of these actions using their own preexisting behavioral strategies. In the current study, chimpanzees (Pan troglodytes) and human children (Homo sapiens) were shown different demonstrations of how to open a tube-in both cases by a conspecific. In different experimental conditions, demonstrations consisted of (1) action only (the actions necessary to open the tube without actually opening it); (2) end state only (the open tube, without showing any actions); (3) both of these components (in a full demonstration); or (4) neither of these components (in a baseline condition). In the first three conditions subjects saw one of two different ways that the tube could open (break in middle; caps off ends). Subjects' behavior in each condition was assessed for how often they opened the tube, how often they opened it in the same location as the demonstrator, and how often they copied the demonstrator's actions or style of opening the tube. Whereas chimpanzees reproduced mainly the environmental results of the demonstrations (emulation), human children often reproduced the demonstrator's actions (imitation). Because the procedure used was similar in many ways to the procedure that Meltzoff (Dev Psych 31:1, 1995) used to study the understanding of others' unfulfilled intentions, the implications of these findings with regard to chimpanzees' understanding of others' intentions are also discussed.
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Hothersall, B., Gale, E., Harris, P., & Nicol, C. (2010). Cue use by foals (Equus caballus) in a discrimination learning task. Anim. Cogn., 13(1), 63–74.
Abstract: Abstract Discrimination learning studies suggest that horses learn more easily using spatial than visible object-specific (OS) cues. However, spatial cues have generally confounded intra-array, distal and/or egocentric spatial information. It is also unclear whether conflicting cues compete for association or are redundantly encoded, and furthermore, the influence of prior experiences or training has not been quantified so far. We examined the effect of cue modality on unweaned foals’ performance in a discrimination learning task. After a pilot study confirmed that horses could perform the required OS cue discrimination, nine foals learnt to find food in one of three covered buckets, in any of four positions within a test arena. In Stage 1 the rewarded bucket was signified both by OS cues (pattern) and by relative spatial cues (position). On reaching criterion, cues were separated and foals had to ignore the inappropriate cue (Stage 2). Foals assigned to follow spatial cues (n = 5) completed Stage 2 faster than foals for whom OS cues remained consistent (n = 4). Spatial group foals all reached criterion without delay; no foal in the OS group reached criterion within the testing period. OS group foals initially persisted in responding to the previously correct position, adopting spatially-based strategies when this proved unsuccessful. The findings show for the first time that, even in the absence of distal spatial information, intra-array spatial cues were more salient than OS cues for foals in a food-finding task and learning appeared rather inflexible.
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