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Jackson, R. R., & Li, D. (2004). One-encounter search-image formation by araneophagic spiders. Anim. Cogn., 7(4), 247–254.
Abstract: An experimental study of search-image use by araneophagic jumping spiders (i.e., salticid spiders that prey routinely on other spiders) supports five conclusions. First, araneophagic salticids have an innate predisposition to form search images for specific prey from their preferred prey category (spiders) rather than for prey from a non-preferred category (insects). Second, single encounters are sufficient for forming search images. Third, search images are based on selective attention specifically to optical cues. Fourth, there are trade-offs in attention during search-image use (i.e., forming a search image for one type of spider diminishes the araneophagic salticid's attention to other spiders). Fifth, the araneophagic salticid's adoption of search images is costly to the prey (i.e., when the araneophagic salticid adopts a search, the prey's prospects for surviving encounters with the araneophagic salticid are diminished). Cognitive and ecological implications of search-image use are discussed.
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Blaisdell, A. P., & Cook, R. G. (2005). Integration of spatial maps in pigeons. Anim. Cogn., 8(1), 7–16.
Abstract: The integration of spatial maps in pigeons was investigated using a spatial analog to sensory preconditioning. The pigeons were tested in an open-field arena in which they had to locate hidden food among a 4x4 grid of gravel-filled cups. In phase 1, the pigeons were exposed to a consistent spatial relationship (vector) between landmark L (a red L-shaped block of wood), landmark T (a blue T-shaped block of wood) and the hidden food goal. In phase 2, the pigeons were then exposed to landmark T with a different spatial vector to the hidden food goal. Following phase 2, pigeons were tested with trials on which they were presented with only landmark L to examine the potential integration of the phase 1 and 2 vectors via their shared common elements. When these test trials were preceded by phase 1 and phase 2 reminder trials, pigeons searched for the goal most often at a location consistent with their integration of the L-->T phase 1 and T-->phase 2 goal vectors. This result indicates that integration of spatial vectors acquired during phases 1 and 2 allowed the pigeons to compute a novel L-->goal vector. This suggests that spatial maps may be enlarged by successively integrating additional spatial information through the linkage of common elements.
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O'Connell, S., & Dunbar, R. I. M. (2005). The perception of causality in chimpanzees (Pan spp.). Anim. Cogn., 8(1), 60–66.
Abstract: Chimpanzees (Pan spp.) were tested on a habituation/dishabituation paradigm that was originally developed to test for comprehension of causality in very young human infants. Three versions of the test were used: a food item being moved by a hand, a human pushing another human off a chair to obtain a food item, and a film clip of natural chimpanzee behaviour (capturing and eating a monkey). Chimpanzees exhibited similar results to those obtained with human infants, with significantly elevated levels of looking on the dishabituation trials. Since the level of response was significantly greater on natural/unnatural sequences than on unnatural/natural sequences, we conclude that the chimpanzees were not responding just to novelty but rather to events that infringed their sense of natural causation.
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Osthaus, B., Lea, S. E. G., & Slater, A. M. (2005). Dogs (Canis lupus familiaris) fail to show understanding of means-end connections in a string-pulling task. Anim. Cogn., 8(1), 37–47.
Abstract: Domestic dogs (Canis lupus familiaris) were tested in four experiments for their understanding of means-end connections. In each of the experiments, the dogs attempted to retrieve a food treat that could be seen behind a barrier and which was connected, via string, to a within-reach wooden block. In the experiments, either one or two strings were present, but the treat was attached only to one string. Successful retrieval of the treat required the animals to pull the appropriate string (either by pawing or by grasping the wooden block in their jaws) until the treat emerged from under the barrier. The results showed that the dogs were successful if the treat was in a perpendicular line to the barrier, i.e. straight ahead, but not when the string was at an angle: in the latter condition, the typical response was a proximity error in that the dogs pawed or mouthed at a location closest in line to the treat. When two strings that crossed were present, the dogs tended to pull on the wrong string. The combined results from the experiments show that, although dogs can learn to pull on a string to obtain food, they do not spontaneously understand means-end connections involving strings.
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Gazit, I., Goldblatt, A., & Terkel, J. (2005). The role of context specificity in learning: the effects of training context on explosives detection in dogs. Anim. Cogn., 8(3), 143–150.
Abstract: Various experiments revealed that if an animal learns a stimulus-response-reinforcer relationship in one context and is then tested in another context there is usually a lessening of stimulus control, and the same discriminative stimuli that reliably controlled the behavior in the first context will have less effect in the new context. This reduction in performance is known as the “context shift effect.” The effect of changing context on the probability of detecting explosives was investigated in seven highly trained explosives detection dogs (EDDs). In experiment 1 the dogs were trained alternately on path A, which always had five hidden explosives, and on a very similar path B, which never had any explosives. Within a few sessions the dogs showed a significant decrease in search behavior on path B, but not on path A. In experiment 2 the same dogs were trained only on path B with a target density of one explosive hidden every 4th day. The probability of the dogs now detecting the explosive was found to be significantly lower than in experiment 1. In experiment 3 the effect of the low target density as used in experiment 2 was investigated on a new but very similar path C. Both the detection probability for the one explosive every 4th day on the new path and the motivation to search were significantly higher than found in experiment 2. Finally, in experiment 4, an attempt was made to recondition the dogs to search on path B. Although trained for 12 daily sessions with one explosive hidden every session, the dogs failed to regain the normal levels of motivation they had shown on both new paths and on the paths that they knew usually contained explosives. The findings reveal that even a very intensively trained EDD will rapidly learn that a specific stretch of path does not contain explosives. The dog will then be less motivated to search and will miss newly placed targets. This learning is specific to the formerly always-clean path and is to some extent irreversible. However, the dog will search and detect normally on new paths even if they are very similar to the always-clean path. The data are discussed in terms of variables affecting renewal. The results suggest that following training designed to make a behavior “context independent,” any extinction training will not generalize beyond that specific context used during the extinction training. In addition, if the behavior is extinguished in a specific context, it will be very difficult to restore that behavior in that context. These conclusions should be considered by anyone attempting to extinguish well-established trans-context behaviors.
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Ducoing, A. M., & Thierry, B. (2005). Tool-use learning in Tonkean macaques (Macaca tonkeana). Anim. Cogn., 8(2), 103–113.
Abstract: The transmission of tool use is a rare event in monkeys. Such an event arose in a group of semi-free-ranging Tonkean macaques (Macaca tonkeana) in which leaning a pole against the park's fence (branch leaning) appeared and spread to several males. This prompted us to test individual and social learning of this behavior in seven young males. In the first experiment, three males learned individually to obtain a food reward using a wooden pole as a climbing tool. They began using the pole to retrieve the reward only when they could alternatively experience acting on the object and reaching the target. In a second experiment, we first tested whether four other subjects could learn branch leaning after having observed a group-mate performing the task. Despite repeated opportunities to observe the demonstrator, they did not learn to use the pole as a tool. Hence we exposed the latter subjects to individual learning trials and they succeeded in the task. Tool use was not transmitted in the experimental situation, which contrasts with observations in the park. We can conclude that the subjects were not able to recognize the target as such. It is possible that they recognized it and learned the task individually when we alternated the opportunity to act upon the object and to reach the reward. This suggests that these macaques could then have associated the action they exercised upon the pole and the use of the pole as a means to reach the reward.
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Cole, P. D., & Adamo, S. A. (2005). Cuttlefish (Sepia officinalis: Cephalopoda) hunting behavior and associative learning. Anim. Cogn., 8(1), 27–30.
Abstract: Because most learning studies in cephalopods have been performed on octopods, it remains unclear whether such abilities are specific to octopus, or whether they correlate with having a larger and more centrally organized brain. To investigate associative learning in a different cephalopod, six sexually mature cuttlefish (Sepia officinalis) participated in a counterbalanced, within-subjects, appetitive, classical conditioning procedure. Two plastic spheres (conditioned stimuli, CSs), differing in brightness, were presented sequentially. Presentation of the CS+ was followed 5 s later by a live feeder fish (unconditioned stimulus, US). Cuttlefish began to attack the CS+ with the same type of food-acquisition seizures used to capture the feeder fish. After seven blocks of training (42 presentations of each CS) the difference in seizure probability between CS+ and CS- trials more than doubled; and was found to be significantly higher in late versus early blocks. These results indicate that cuttlefish exhibit autoshaping under some conditions. The possible ecological significance of this type of learning is briefly discussed.
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Hodgson, Z. G., & Healy, S. D. (2005). Preference for spatial cues in a non-storing songbird species. Anim. Cogn., 8(3), 211–214.
Abstract: Male mammals typically outperform their conspecific females on spatial tasks. A sex difference in cues used to solve the task could underlie this performance difference as spatial ability is reliant on appropriate cue use. Although comparative studies of memory in food-storing and non-storing birds have examined species differences in cue preference, few studies have investigated differences in cue use within a species. In this study, we used a one-trial associative food-finding task to test for sex differences in cue use in the great tit, Parus major. Birds were trained to locate a food reward hidden in a well covered by a coloured cloth. To determine whether the colour of the cloth or the location of the well was learned during training, the birds were presented with three wells in the test phase: one in the original location, but covered by a cloth of a novel colour, a second in a new location covered with the original cloth and a third in a new location covered by a differently coloured cloth. Both sexes preferentially visited the well in the training location rather than either alternative. As great tits prefer colour cues over spatial cues in one-trial associative conditioning tasks, cue preference appears to be related to the task type rather than being species dependent.
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Held, S., Baumgartner, J., Kilbride, A., Byrne, R. W., & Mendl, M. (2005). Foraging behaviour in domestic pigs (Sus scrofa): remembering and prioritizing food sites of different value. Anim. Cogn., 8(2), 114–121.
Abstract: This experiment investigated whether domestic pigs can remember the locations of food sites of different relative value, and how a restricted retrieval choice affects their foraging behaviour. Nine juvenile female pigs were trained to relocate two food sites out of a possible eight in a spatial memory task. The two baited sites contained different amounts of food and an obstacle was added to the smaller amount to increase handling time. On each trial, a pig searched for the two baited sites (search visit). Once it had found and eaten the bait, it returned for a second (relocation) visit, in which the two same sites were baited. Baited sites were changed between trials. All subjects learnt the task. When allowed to retrieve both baits, the subjects showed no preference for retrieving a particular one first (experiment 1). When they were allowed to retrieve only one bait, a significant overall preference for retrieving the larger amount emerged across subjects (experiment 2). To test whether this preference reflected an avoidance of the obstacle with the smaller bait, 15 choice-restricted control trials were conducted. In control trials obstacles were present with both baits. Pigs continued to retrieve the larger bait, indicating they had discriminated between the two food sites on the basis of quantity or profitability and adjusted their behaviour accordingly when the relocation choice was restricted. This suggests for the first time that domestic pigs have the ability to discriminate between food sites of different relative value and to remember their respective locations.
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Santos, L. R., Pearson, H. M., Spaepen, G. M., Tsao, F., & Hauser, M. D. (2006). Probing the limits of tool competence: experiments with two non-tool-using species (Cercopithecus aethiops and Saguinus oedipus). Anim. Cogn., 9(2), 94–109.
Abstract: Non-human animals vary in their ability to make and use tools. The goal of the present study was to further explore what, if anything, differs between tool-users and non-tool-users, and whether these differences lie in the conceptual or motor domain. We tested two species that typically do not use tools-cotton top tamarins (Saguinus oedipus) and vervet monkeys (Cercopithecus aethiops)-on problems that mirrored those designed for prolific tool users such as chimpanzees. We trained subjects on a task in which they could choose one of two canes to obtain an out-of-reach food reward. After training, subjects received several variations on the original task, each designed to examine a specific conceptual aspect of the pulling problem previously studied in other tool-using species. Both species recognized that effective pulling tools must be made of rigid materials. Subsequent conditions revealed significant species differences, with vervets outperforming tamarins across many conditions. Vervets, but not tamarins, had some recognition of the relationship between a tool's orientation and the position of the food reward, the relationship between a tool's trajectory and the substance that it moves on, and that tools must be connected in order to work properly. These results provide further evidence that tool-use may derive from domain-general, rather than domain-specific cognitive capacities that evolved for tool use per se.
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