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Mateo, J. M., & Johnston, R. E. (2003). Kin recognition by self-referent phenotype matching: weighing the evidence. Anim. Cogn., 6(1), 73–76.
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Hauber, M. E., & Sherman, P. W. (2003). Designing and interpreting experimental tests of self-referent phenotype matching. Anim. Cogn., 6(1), 69–71.
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van der Willigen, R. F., Frost, B. J., & Wagner, H. (2003). How owls structure visual information. Anim. Cogn., 6(1), 39–55.
Abstract: Recent studies on perceptual organization in humans claim that the ability to represent a visual scene as a set of coherent surfaces is of central importance for visual cognition. We examined whether this surface representation hypothesis generalizes to a non-mammalian species, the barn owl ( Tyto alba). Discrimination transfer combined with random-dot stimuli provided the appropriate means for a series of two behavioural experiments with the specific aims of (1) obtaining psychophysical measurements of figure-ground segmentation in the owl, and (2) determining the nature of the information involved. In experiment 1, two owls were trained to indicate the presence or absence of a central planar surface (figure) among a larger region of random dots (ground) based on differences in texture. Without additional training, the owls could make the same discrimination when figure and ground had reversed luminance, or were camouflaged by the use of uniformly textured random-dot stereograms. In the latter case, the figure stands out in depth from the ground when positional differences of the figure in two retinal images are combined (binocular disparity). In experiment 2, two new owls were trained to distinguish three-dimensional objects from holes using random-dot kinematograms. These birds could make the same discrimination when information on surface segmentation was unexpectedly switched from relative motion to half-occlusion. In the latter case, stereograms were used that provide the impression of stratified surfaces to humans by giving unpairable image features to the eyes. The ability to use image features such as texture, binocular disparity, relative motion, and half-occlusion interchangeably to determine figure-ground relationships suggests that in owls, as in humans, the structuring of the visual scene critically depends on how indirect image information (depth order, occlusion contours) is allocated between different surfaces.
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Neiworth, J. J., Steinmark, E., Basile, B. M., Wonders, R., Steely, F., & DeHart, C. (2003). A test of object permanence in a new-world monkey species, cotton top tamarins (Saguinus oedipus). Anim. Cogn., 6(1), 27–37.
Abstract: Cotton top tamarins were tested in visible and invisible displacement tasks in a method similar to that used elsewhere to test squirrel monkeys and orangutans. All subjects performed at levels significantly above chance on visible ( n=8) and invisible ( n=7) displacements, wherein the tasks included tests of the perseverance error, tests of memory in double and triple displacements, and “catch” trials that tested for the use of the experimenter's hand as a cue for the correct cup. Performance on all nine tasks was significantly higher than chance level selection of cups, and tasks using visible displacements generated more accurate performance than tasks using invisible displacements. Performance was not accounted for by a practice effect based on exposure to successive tasks. Results suggest that tamarins possess stage 6 object permanence capabilities, and that in a situation involving brief exposure to tasks and foraging opportunities, tracking objects' movements and responding more flexibly are abilities expressed readily by the tamarins.
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Weatherly, J. N., Arthur, E. I. L., & Tischart, L. M. (2003). Altering “motivational” variables alters induction produced by upcoming food-pellet reinforcement. Anim. Cogn., 6(1), 17–26.
Abstract: Previous research has demonstrated that rats will increase their rates of lever pressing for sucrose rewards in the first half of an experimental session when food pellets, rather than the same sucrose, continually serve as the reward in the second half of the session. This effect has been coined induction, and the present study investigated whether it could be altered by altering “motivational” variables. Experiment 1 manipulated subjects' motivation by altering, across conditions, their level of food deprivation. Predictably, the size of induction varied directly with level of deprivation. Experiments 2 and 3 manipulated subjects' motivation by feeding them food pellets and sucrose, respectively, prior to their responding in the experimental session. These pre-session feedings decreased the size of the observed induction in both experiments. The results from the present study indicate that the size of induction is correlated with subjects' motivation to respond for the available reinforcers. They are also consistent with the idea that operant processes underlie the effect. The notion that induction might encompass the concept of “anticipation” is also discussed.
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Katz, M., & Lachlan, R. F. (2003). Social learning of food types in zebra finches (Taenopygia guttata) is directed by demonstrator sex and feeding activity. Anim. Cogn., 6(1), 11–16.
Abstract: In this study we examined how social learning of feeding preferences by zebra finches was affected by the identity of different demonstrators. We presented adult zebra finches with two demonstrators, one male and one female, that exhibited different food choices, and we recorded their subsequent preference when given a choice between the two food types. Previously it was found that young zebra finches' patterns of social learning are affected by the sex of the individual demonstrating a feeding behaviour. This result could be explained by the lack of exposure these animals had to the opposite sex, or by their mating status. Therefore, we investigated the social learning preferences of adult mated zebra finches. We found the same pattern of directed social learning of a different type of feeding behaviour (food colour): female zebra finches preferred the colour of food eaten by male demonstrators, whereas male zebra finches showed little evidence of any preference for the colour of food eaten by female demonstrators. Furthermore, we found that female observers' preferences were biased by demonstrators' relative feeding activity: the female demonstrator was only ever preferred if it ate less than its male counterpart.
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Fiset, S., Beaulieu, C., & Landry, F. (2003). Duration of dogs' (Canis familiaris) working memory in search for disappearing objects. Anim. Cogn., 6(1), 1–10.
Abstract: Two experiments explored the duration of dogs' working memory in an object permanence task: a delay was introduced between the disappearance of a moving object behind a box and the beginning of the search by the animal. In experiment 1, the dogs were tested with retention intervals of 0, 10, 30, and 60 s. Results revealed that the dogs' accuracy declined as a function of the length of the retention interval but remained above chance for each retention interval. In experiment 2, with new subjects, longer retention intervals (0, 30, 60, 120, and 240 s) were presented to the dogs. Results replicated findings from experiment 1 and revealed that the dogs' accuracy remained higher than chance level with delays up to 240 s. In both experiments, the analysis of errors also showed that the dogs searched as a function of the proximity of the target box and were not subject to intertrial proactive interference. In the discussion, we explore different alternatives to explain why dogs' search behaviour for hidden objects decreased as a function of the retention intervals.
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Loyola, E. G., Rodriguez, M. H., Gonzalez, L., Arredondo, J. I., Bown, D. N., & Vaca, M. A. (1990). Effect of indoor residual spraying of DDT and bendiocarb on the feeding patterns of Anopheles pseudopunctipennis in Mexico. J Am Mosq Control Assoc, 6(4), 635–640.
Abstract: Intense and persistent use of DDT for malaria control has increased resistance and induced exophilic behavior of Anopheles pseudopunctipennis. An evaluation of bendiocarb and DDT to control this species in Sinaloa, Mexico, showed that, in spite of DDT-resistance, both insecticides produced similar effects. Feeding patterns were analyzed to explain these results. Resting mosquitoes were collected over the dry and wet seasons. Anophelines were tested in an ELISA to determine the source of the meals. The human blood index (HBI) ranged from 3.3 to 6.8% in DDT- and from 12.7 to 26.9% in bendiocarb-sprayed houses. Irritability and repellency in DDT-sprayed houses could explain the reduced HBI. In contrast, bendiocarb produced higher mortality. These effects could have affected different components of the vectorial capacity and similarly reduced malaria.
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Parker, S. T. (1997). A general model for the adaptive function of self-knowledge in animals and humans. Conscious Cogn, 6(1), 75–86.
Abstract: This article offers a general definition of self-knowledge that embraces all forms and levels of self-knowledge in animals and humans. It is hypothesized that various levels of self-knowledge constitute an ordinal scale such that each species in a lineage displays the forms of self-knowledge found in related species as well as new forms it and its sister species may have evolved. Likewise, it is hypothesized that these various forms of levels of self-knowledge develop in the sequence in which they evolved. Finally, a general hypothesis for the functional significance of self-knowledge is proposed along with subhypotheses regarding the adaptive significance of various levels of self-knowledge in mammals including human and nonhuman primates. The general hypothesis is that self-knowledge serves as a standard for assessing the qualities of conspecifics compared to those of the self. Such assessment is crucial to deciding among alternative reproductive and subsistence strategies. The qualities that are assessed, which vary across taxa, range from the size and strength of the self to its mathematical or musical abilities. This so-called assessment model of self-knowledge is based on evolutionary biological models for social selection and the role of assessment in animal communication.
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Hillidge, C. J., & Lees, P. (1975). Cardiac output in the conscious and anaesthetised horse. Equine Vet J, 7(1), 16–21.
Abstract: Cardiac output in the horse was measured before and at predetermined times during 2-hour periods of thiopentone-halothane and thiopentone-diethyl ether anaesthesia. Left ventricular stroke volume was decreased to a similar extent during anaesthesia with each volatile agent, but a greater reduction in cardiac output occurred during halothane anaesthesia. This finding reflected the differing effects of halothane and ether on heart rate, a slight bradycardia occurring with the former agent while ether produced a small degree of tachycardia. The latter effect was attributed to enhanced sympathoadrenal activity. Changes in cardiac output and stroke volume were considered in relation to other factors, including arterial blood pH and tensions of oxygen and carbon dioxide. Positive correlations between some of these variables and cardiac function were established. With both volatile agents the reductions in stroke volume and cardiac output were related to the duration of anaesthesia, being greatest during the early stages. Possible reasons for the tendency of stroke volume and cardiac output to return towards control levels are discussed.
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