Fiset, S. & Ouellette, M. (Juin, 1998). Estimation angulaire chez le chien domestique [Angular estimation in domestic dogs (Canis familliaris)],

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1 Fiset, S. & Ouellette, M. (June, 1998). Angular estimation in domestic dogs (Canis familliaris), Poster presented at the 8 th annual meeting of the Canadian Society for Brain, Behaviour and Cognitive Science, Carleton University, Ottawa. Abstract This research was aimed at determining the accuracy of the angular estimation in domestic dogs when they locate a spatial position by using egocentric spatial information. The general procedure consisted to hide an attractive object behind one of the four screens that were placed in front of the subject. The angular deviation between the screens was manipulated by varying the distance between the subject s position and the row of screens. Four different angles were tested: 5 o, 7.5 o, 10 o and 15 o. Seven subjects participated to this experiment. Results indicated that dogs performance was as a function of the angular deviation between the screens: their performance was higher with a large angle (15 o ) that with a small angle (5 o ). Nevertheless, their performance was highly above chance in each condition. In conclusion, it seems that dogs spatial representation of a hiding location is based on a highly accurate egocentric estimation of the direction by which an object has disappeared.

2 Fiset, S. & Ouellette, M. (Juin, 1998). Estimation angulaire chez le chien domestique [Angular estimation in domestic dogs (Canis familliaris)], Communication présentée au 8e congrès annuel de la Canadian Society for Brain, Behaviour and Cognitive Science, Carleton University, Ottawa. Résumé L objectif de la présente expérience est de vérifier la précision de l estimation angulaire chez le chien domestique lorsqu il utilise l information spatiale égocentrique pour retrouver un objet disparu. La procédure expérimentale consiste à dissimuler un objet attrayant derrière l un des quatre écrans placés devant le sujet. L angle de déviation entre les écrans est manipulé en variant la distance entre la position du sujet et les quatre écrans. Quatre différents angles sont testés : 5 0, 7.5 0, 10 0 et Sept chiens adultes, provenant de la région d Edmundston, participent à l expérience. Les résultats indiquent que la performance des chiens est significativement meilleure avec un angle de 15 0 qu avec un angle de 5 0. Cependant, la performance des chiens est nettement au-dessus du hasard dans chacune des conditions expérimentales. En conclusion, il semble que la représentation spatiale d un lieu de disparition chez le chien domestique est basée sur une estimation égocentrique très précise de la direction par laquelle un objet a disparu.

3 Introduction Recently, Gallistel (1990) has proposed that animals localise a spatial position by using some sources of metric information (angles and distances). This metric hypothesis has been tested and confirmed in several species (Cheng, 1994, Cheng & Sherry, 1992, Cheng & Spetch, 1995; Spetch & Mondloch, 1993), including humans (Spetch, Cheng & MacDonald, 1996; Spetch et al, 1997), when animals encode and use allocentric spatial information, that is, when animals encode and use different visual landmarks (rocks, trees, etc.... ) to localise a spatial position. However, when the animals localise a spatial position by using their own spatial coordinates (egocentric spatial information), do the animals use a form of metric representation? Landry et Fiset (1997) has tested this hypothesis by putting in conflict direction (angle) and distance between the animal s position and the spatial location. Their results indicated that in domestic dogs (Canis familiaris), egocentric spatial representation is essentially based on directional information. In the present study, we determine the accuracy of the angular estimation made by dogs when they locate a spatial position by using egocentric spatial information.

4 Method Subjects We used seven purebreds adult dogs (Canis familliaris; two females and five males): One German Sherpherd dog, one Boxer, one Dalmatian, two Golden Retrievers and three Labrador Retrievers. Apparatus Four (A, B, C, D) identical wooden boxes (29.9 cm wide x high cm x cm deep) painted in white with a top, a front and two side panels but no back panel were used to hide the object. They were placed on a row on a grey rubber carpet (552.5 cm x cm) where they could be placed on four different positions (P1, P2, P3, P4) on the carpet which were marked with tape (Figure 1). The target object was either a rubber squeezable toy or a tennis ball depending on subjects' preference. Each object was manipulated by a transparent nylon thread (125 cm) tied to it. Testing sessions were administered either in the owner's house or in the owner s backyard.

5 184,65 cm A B C D E1 P4 5 o P3 7,5 o P2 552,45 cm P1 15 o SUJET E2 Figure 1 Experimental apparatus.

6 Procedure For each step, we used the following procedure: An experimenter (E1) who stood up 50 cm behind the screens B and C, captured the dog s attention by moving the target object with the nylon thread. Once the dog looked at the object, E1 moved the object visibly in front of the screens, and finally put it down between two screens (shaping) or behind a screen (training and testing). Meanwhile, the second experimenter (E2) was restraining the dog by holding its collar and made sure that the subject visually followed the object's displacement. Once the object was put down, the subject was released. Shaping - We introduced a food reinforcement procedure to prevent any motivation decline during the experiment. The dog was reinforced if one of the following behaviours was exhibited: Grasping the object with its mouth, touching it with its paw or putting its muzzle on it. A piece of commercial dry food (Diet NutriScience) and social reinforcements (strokes, verbal rewards like Good dog! ) were used as reinforcers. Training We trained the dogs to find the target object behind a screen. In

7 training, two screens (A and D) were placed on the carpet and from trial to trial, they were randomly moved from P1 to P4 (Figure 2). In P4, the two screens were separated by an angle of 15 degrees. Through this procedure, we made sure that the dogs can find the object whatever else the position (distance) at which it was hidden on the carpet and that they can find the object when the screens were separated by an angle of 15 degrees. The training session included a minimum of 16 trials and the object was hidden four times in each of the four positions. Testing During this step, we manipulated the angular deviation between the screens by varying the distance between the subject s position and the row of screens. In each trial of testing, the four screens (A, B, C, D) were placed on one of the four positions (P1, P2, P3, P4) on the carpet. For each position, the angular deviation between two adjacent screens was 5, 7.5, 10 and 15 degrees, respectively (see Figure 1). In testing, there were four sessions of 20 trials each. At the end of testing, the target object had been hidden five times behind each screen for each position. Therefore, each angle was tested by 20 trials.

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9 Results First, dogs performance in training was very high: Only one error as been made in 112 trials and it occurred when the screens were in P1. Therefore, we can conclude that dogs performance was not disturbed by the distance (or position) to which the screens were placed on the carpet. Second, Figure 3 shows the mean percentage of success as a function of degrees. It can be seen that dogs performance decreased when the angles were smaller. A within-subject ANOVA confirmed a significant difference between the degrees, F (3,18) = 4.70, p <.05. A posteriori Newman-Keuls test (p <.05) revealed that dogs performance was higher with an angle of 15 0 (M = 97.74, SD = 3.83) than with an angle of 5 0 (M = 85.03, SD = 11.02).

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11 Discussion Although we observed that dogs performance decreased as a function of angles, subjects performance was nevertheless highly above chance in each condition (85% of success and more). Therefore, it seems that dogs spatial representation of a hiding location is based on a highly accurate egocentric estimation of the direction by which an object has disappeared. Next studies on metric representation in domestic dogs should use more accurate procedures than that used in the present experiment. Indeed, in the present experiment, our metric estimations were limited to four angles. We are now working on an adaptation of the landmark-based search task, initially developed by Cartwright and Collett (1983) and used by Cheng and his colleagues (Cheng, 1989; 1990; 1994; Cheng & Sherry, 1992; Cheng & Spetch, 1995; Spetch, Cheng & MacDonald, 1996; Spetch & al. 1997; Spetch and Mondloch, 1992), to test dogs metric representation in egocentric and allocentric spatial situations.

12 References Cartwright, B. A. & Collect, T. S. (1983). Landmark learning in bees. Journal of Comparative Physiology A, 151, Cheng, K. (1989). The vector sum model of pigeon landmark use. Journal of Experimental Psychology: Animal Behavior Processes, 15, Cheng, K. (1994). The determination of direction in landmark-based spatial search in pigeons: A further test of the vector sum model. Animal Learning & Behavior 22(3): Cheng, K. and D. F. Sherry (1992). Landmark-based spatial memory in birds (Parus atricapillus and Columba livia): the use of edges and distances to represent spatials positions. Journal of Comparative Psychology 106(4): Gallistel, C. R. (1990). The organization of learning. Cambridge, The MIT Press. Landry, F. & Fiset, S. (1997). Représentation spatial d'un objet disparu selon

13 un vecteur de direction chez le chien domestique, Communication présentée lors du 20ième congrès annuel de la Société Québécoise de la Recherche en Psychologie, Sherbrooke. Spetch, M. L., K. Cheng, et al. (1996). Learning the configuration of a landmark array: I. Touch-screen studies with pigeons and humans. Journal of Comparative Psychology 110: Spetch, M. L., K. Cheng, et al. (1997). Use of landmark configuration in pigeons and humans: II. Generality across search tasks. Journal of Comparative Psychology 111(1): Spetch, M. L. and M. V. Mondlock (1992). Control of pigeons' spatial search by graphic landmarks in a touch-screen task. Journal of Experimental Psychology: Animal Behavior Processes 19: