1,721,508 research outputs found
Ape metaphysics: Object individuation without language
Full text linkDevelopmental research suggests that whereas very young infants individuate objects purely on spatiotemporal grounds, from (at latest) around 1 year of age children are capable of individuating objects according to the kind they belong to and the properties they instantiate. As the latter ability has been found to correlate with language, some have speculated whether it might be essentially language dependent and therefore uniquely human. Existing studies with non-human primates seem to speak against this hypothesis, but fail to present conclusive evidence due to methodological shortcomings. In the present experiments we set out to test non-linguistic object individuation in three great ape species with a refined manual search methodology. Experiment 1 tested for spatiotemporal object individuation: Subjects saw 1 or 2 objects simultaneously being placed inside a box in which they could reach, and then in both conditions only found 1 object. After retrieval of the 1 object, subjects reached again significantly more often when they had seen 2 than when they had seen 1 object. Experiment 2 tested for object individuation according to property/kind information only: Subjects saw 1 object being placed inside the box, and then either found that object (expected) or an object of a different kind (unexpected). Analogously to Experiment 1, after retrieval of the 1 object, subjects reached again significantly more often in the unexpected than in the expected condition. These results thus confirm previous findings suggesting that individuating objects according to their property/kind is neither uniquely human nor essentially language dependent. It remains to be seen, however, whether this kind of object individuation requires sortal concepts as human linguistic thinkers use them, or whether some simpler form of tracking properties is sufficient. (C) 2007 Elsevier B.V. All rights reserved.</p
Are apes essentialists? Scope and limits of psychological essentialism in great apes
Full text linkHuman reasoning is characterized by psychological essentialism (Gelman in The essential child: origins of essentialism in everyday thought. Oxford University Press, New York, 2003): when reasoning about objects, we distinguish between deep essential properties defining the object's kind and identity, and merely superficial features that can be changed without altering the object's identity. To date, it is unclear whether psychological essentialism is based on the acquisition of linguistic means (such as kind terms) and therefore uniquely human, or whether it is a more fundamental cognitive capacity which might be present also in the absence of language. In the present study, we addressed this question by testing whether, and if so, under which circumstances non-human apes also rely on psychological essentialism to identify objects. For this purpose, we adapted classical verbal transformation scenarios used in research on psychological essentialism (Keil in Concepts, kinds, and cognitive development. MIT Press, Cambridge, 1989) and implemented them in two nonverbal tasks: first, a box task, typically used to test object individuation (Experiment 1), and second, an object choice task, typically used to test object discrimination, object preferences and logical inferences (Experiments 2-4). Taken together, the results of the four experiments suggest that under suitable circumstances (when memory and other task demands are minimized), great apes engage in basic forms of essentialist reasoning. Psychological essentialism is thus possible also in the absence of languag
Prospective object search in dogs: mixed evidence for knowledge of What and Where
Full text linkWe investigated whether two dogs that had been specially trained to retrieve objects by their names were able to integrate information about the identity (What) as well as the location (Where) of those objects so that they could plan their search accordingly. In a first study, two sets of objects were placed in two separate rooms and subjects were asked to retrieve the objects, one after the other. Both dogs remembered the identity of the objects as they reliably retrieved the correct objects. One of the dogs was also able to integrate information about the object's location as he chose the correct location in which the object had been placed. Further investigation of the second dog's behavior revealed that she followed a more stereotyped search strategy. Despite this variation in performance, this study provides evidence for the memory of What and Where in a domestic dog and shows the prospective use of such information in a search task.</p
Primates do not spontaneously use shape properties for object individuation: a competence or a performance problem?
Full text linkSeveral recent studies have documented that non-human primates can individuate objects according to property and/or kind information in much the same way as human infants do from around one year of age when they begin to acquire language. Some studies suggest, however, that only some properties are used for the individuation of food items: color, but not shape. The present study investigated whether these findings reveal a true competence problem with shape properties in the food domain or whether they merely reveal a performance problem (e.g., lack of attention to shapes). We tested 25 great apes (chimpanzees, bonobos and gorillas) in two food individuation tasks. We manipulated subjects' experience with differences in color and shape properties of food items. Results indicated (i) that all subjects, regardless of their prior experience, solved the color-based object individuation task and (ii) that only the group with previous experience with different shape properties succeeded in the shape-based individuation task. Great apes can thus be primed to take shape into account for individuating food objects, and this results clearly speaks in favor of a performance (rather than a competence) problem in using shape for object individuation of food items.</p
Intuitive statistics in non-human primates
No full textBackground / Purpose: This study investigates intuitive statistics in non-human primates (chimpanzees, bonobos, gorillas and orangutans) and is based on previous work on intuitive statistics in human infants (1). In a series of experiments we tested whether non-human primates can reason about the likelihood of a particular food item being drawn from two mixed populations of food items (carrot pieces and banana pellets, where the banana pellets are by far preferred by the animals). Importantly, the distribution of the two items and thus the relative frequency of drawing a banana pellet differed between the populations (e.g. 64:16 of banana : carrot in one bucket vs. 16:64 in the other). Main conclusion: We found evidence of intuitive statistics in this group of great apes: in the majority of trials, the animals chose the sample stemming from the population with a higher relative frequency of their preferred item (banana pellet). We ruled out alternative accounts, such as Clever Hans effects and odour discrimination
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