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Vallortigara, G., Regolin, L., Rigoni, M., & Zanforlin, M. (1998). Delayed search for a concealed imprinted object in the domestic chick. Anim. Cogn., 1(1), 17–24.
Abstract: Five-day-old chicks were accustomed to follow an imprinted object (a small red ball with which they had been reared) that was moving slowly in a large arena, until it disappeared behind an opaque screen. In experiments, each chick was initially confined in a transparent cage, from where it could see and track the ball while it moved towards, and then beyond, one of two screens. The screens could be either identical or differ in colour and pattern. Either immediately after the disappearance of the ball, or with a certain delay, the chick was released and allowed to search for its imprinted object behind either screen. The results showed that chicks took into account the directional cue provided by the ball movement and its concealment, up to a delay period of about 180 s, independently of the perceptual characteristics of the two screens. If an opaque partition was positioned in front of the transparent cage immediately after the ball had disappeared, so that, throughout the delay, neither the goal-object nor the two screens were visible, chicks were still capable of remembering and choosing the correct screen, though over a much shorter period of about 60 s. The results suggest that, at least in this precocial bird species, very young chicks can maintain some form of representation of the location where a social partner was last seen, and are also capable of continuously updating this representation so as to take into account successive displacements of the goal-object.
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Sovrano, V. A., Rainoldi, C., Bisazza, A., & Vallortigara, G. (1999). Roots of brain specializations: preferential left-eye use during mirror-image inspection in six species of teleost fish. Behav. Brain. Res., 106(1-2), 175–180.
Abstract: It has recently been reported that predator inspection is more likely to occur when a companion (i.e. the mirror image of the test animal) is visible on the left rather than on the right side of mosquitofish Gambusia holbrooki. This very unexpected outcome could be consistent with the hypothesis of a preferential use of the right eye during sustained fixation of a predator as well as of a preferential use of the left eye during fixation of conspecifics. We measured the time spent in monocular viewing during inspection of their own mirror images in females of six species of fish, belonging to different families--G. holbrooki, Xenotoca eiseni, Phoxinus phoxinus, Pterophyllum scalare, Xenopoecilus sarasinorum, and Trichogaster trichopterus. Results revealed a consistent left-eye preference during sustained fixation in all of the five species. Males of G. holbrooki, which do not normally show any social behaviour, did not exhibit any eye preferences during mirror-image inspection. We found, however, that they could be induced to manifest a left-eye preference, likewise females, if tested soon after capture, when some affiliative tendencies can be observed. These findings add to current evidence in a variety of vertebrate species for preferential involvement of structures located in the right side of the brain in response to the viewing of conspecifics.
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Siniscalchi, M., Sasso, R., Pepe, A. M., Vallortigara, G., & Quaranta, A. (2010). Dogs turn left to emotional stimuli. Behav. Brain. Res., 208(2), 516–521.
Abstract: During feeding behaviour, dogs were suddenly presented with 2D stimuli depicting the silhouette of a dog, a cat or a snake simultaneously into the left and right visual hemifields. A bias to turn the head towards the left rather than the right side was observed with the cat and snake stimulus but not with the dog stimulus. Latencies to react following stimulus presentation were lower for left than for right head turning, whereas times needed to resume feeding behaviour were higher after left rather than after right head turning. When stimuli were presented only to the left or right visual hemifields, dogs proved to be more responsive to left side presentation, irrespective of the type of stimulus. However, cat and snake stimuli produced shorter latencies to react and longer times to resume feeding following left rather than right monocular visual hemifield presentation. Results demonstrate striking lateralization in dogs, with the right side of the brain more responsive to threatening and alarming stimuli. Possible implications for animal welfare are discussed.
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Quaranta, A., Siniscalchi, M., Frate, A., & Vallortigara, G. (2004). Paw preference in dogs: relations between lateralised behaviour and immunity. Behavioural Brain Research, 153(2), 521–525.
Abstract: Paw use in a task consisting of the removal of a piece of adhesive paper from the snout was investigated in 80 mongrel and pure-bred domestic dogs (Canis familiaris). Population lateralisation was observed, but in opposite directions in the two sexes (animals were not desexed): males preferentially used their left paw, females their right paw. The relationship between immune function and paw preference was then investigated. Some immune parameters (total number of white blood cells including lymphocytes, granulocytes and monocytes; leukocyte formula; total proteins; γ-globulins) were investigated in a sample of left-pawed (n=6), right-pawed (n=6) and ambidextrous (n=6) dogs. The results showed that the percentage of lymphocytes was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas granulocytes percentage was lower in left-pawed than in right-pawed and ambidextrous dogs. Moreover, total number of lymphocytes cells was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas the number of γ-globulins was lower in left-pawed than in right-pawed and ambidextrous dogs. These findings represent the first evidence that brain asymmetry modulates immune responses in dogs.
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Versace, E., Morgante, M., Pulina, G., & Vallortigara, G. (2007). Behavioural lateralization in sheep (Ovis aries). Behav. Brain. Res., 184(1), 72–80.
Abstract: This study investigates behavioural lateralization in sheep and lambs of different ages. A flock was tested in a task in which the animals were facing an obstacle and should avoid it on either the right or left side to rejoin flock-mates (adult sheep) or their mothers (lambs). A bias for avoiding the obstacle on the right side was observed, with lambs apparently being more lateralized than sheep. This right bias was tentatively associated with the left-hemifield laterality in familiar faces recognition which has been documented in this species. Differences between adult sheep and lambs were likely to be due to differences in social reinstatement motivation elicited by different stimuli (flock-mates or mothers) at different ages. Preferential use of the forelegs to step on a wood-board and direction of jaw movement during rumination was also tested in adult animals. No population bias nor individual-level lateralization was observed for use of the forelegs. At the same time, however, there was a large number of animals showing individual-level lateralization for the direction of jaw movement during rumination even though there was no population bias. These findings highlight that within the same species individual- and population-level lateralization can be observed in different tasks. Moreover, the results fit the general hypothesis that population-level asymmetries are more likely to occur in tasks that require social coordination among behaviourally asymmetric individuals.
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Vallortigara, G., & Andrew, R. J. (1994). Differential involvement of right and left hemisphere in individual recognition in the domestic chick. Behav. Process., 33(1-2), 41–57.
Abstract: Right hemisphere advantage in individual recognition (as shown by differences between response to strangers and companions) is clear in the domestic chick. Chicks using the left eye (and so, thanks to the complete optic decussation, predominantly the right hemisphere) discriminate between stranger and companion. Chicks using the right eye discriminate less clearly or not at all. The ability of left eyed chicks to respond to differences between strangers and companions stimuli is associated with a more general ability to detect and respond to novelty: this difference between left and right eyed chicks also holds for stimuli which are not social partners. The right hemisphere also shows advantage in tasks with a spatial component (topographical learning; response to change in the spatial context of a stimulus) in the chick, as in humans. Similar specialisations of the two hemispheres are also revealed in tests which involve olfactory cues presented by social partners. The special properties of the left hemisphere are less well established in the chick. Evidence reviewed here suggests that it tends to respond to selected properties of a stimulus and to use them to assign it to a category; such assignment then allows an appropriate response. When exposed to an imprinting stimulus (visual or auditory) a chick begins by using right eye or ear (suggesting left hemisphere control), and then shifts to the left eye or ear (suggesting right hemisphere control), as exposure continues. The left hemisphere here is thus involved whilst behaviour is dominated by vigorous response to releasing stimuli presented by an object. Subsequent learning about the full detailed properties of the stimulus, which is crucial for individual recognition, may explain the shift to right hemisphere control after prolonged exposure to the social stimulus. There is a marked sex difference in choice tests: females tend to choose companions in tests where males choose strangers. It is possible that this difference is specifically caused by stronger motivation to sustain social contact in female chicks, for which there is extensive evidence. However, sex differences in response to change in familiar stimuli are also marked in tests which do not involve social partners. Finally, in both sexes there are two periods during development in which there age-dependent shifts in bias to use one or other hemisphere. These periods (days 3-5 and 8-11) coincide with two major changes in the social behaviour of chicks reared by a hen in a normal brood. It is argued that one function of these periods is to bring fully into play the hemisphere most appropriate to the type of response to, and learning about, social partners which is needed at particular points in development. Parallels are discussed between the involvement of lateralised processes in the recognition of social partners in chicks and humans.
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Siniscalchi, M., Lusito, R., Vallortigara, G., & Quaranta, A. (2013). Seeing Left- or Right-Asymmetric Tail Wagging Produces Different Emotional Responses in Dogs. Curr Biol, 23(22).
Abstract: Summary Left-right asymmetries in behavior associated with asymmetries in the brain are widespread in the animal kingdom [1], and the hypothesis has been put forward that they may be linked to animals’ social behavior [2, 3]. Dogs show asymmetric tail-wagging responses to different emotive stimuli [4]—the outcome of different activation of left and right brain structures controlling tail movements to the right and left side of the body. A crucial question, however, is whether or not dogs detect this asymmetry. Here we report that dogs looking at moving video images of conspecifics exhibiting prevalent left- or right-asymmetric tail wagging showed higher cardiac activity and higher scores of anxious behavior when observing left- rather than right-biased tail wagging. The finding that dogs are sensitive to the asymmetric tail expressions of other dogs supports the hypothesis of a link between brain asymmetry and social behavior and may prove useful to canine animal welfare theory and practice.
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Quaranta, A., Siniscalchi, M., & Vallortigara, G. (2007). Asymmetric tail-wagging responses by dogs to different emotive stimuli. In Current biology : CB (Vol. 17, pp. R199–R201). Cell Press.
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Quaresmini, C., Forrester, G. S., Spiezio, C., & Vallortigara, G. (2014). Social environment elicits lateralized behaviors in gorillas (Gorilla gorilla gorilla) and chimpanzees (Pan troglodytes). Journal of Comparative Psychology, 128(3), 276–284.
Abstract: The influence of the social environment on lateralized behaviors has now been investigated across a wide variety of animal species. New evidence suggests that the social environment can modulate behavior. Currently, there is a paucity of data relating to how primates navigate their environmental space, and investigations that consider the naturalistic context of the individual are few and fragmented. Moreover, there are competing theories about whether only the right or rather both cerebral hemispheres are involved in the processing of social stimuli, especially in emotion processing. Here we provide the first report of lateralized social behaviors elicited by great apes. We employed a continuous focal animal sampling method to record the spontaneous interactions of a captive zoo-living colony of chimpanzees (Pan troglodytes) and a biological family group of peer-reared western lowland gorillas (Gorilla gorilla gorilla). We specifically focused on which side of the body (i.e., front, rear, left, right) the focal individual preferred to keep conspecifics. Utilizing a newly developed quantitative corpus-coding scheme, analysis revealed both chimpanzees and gorillas demonstrated a significant group-level preference for focal individuals to keep conspecifics positioned to the front of them compared with behind them. More interestingly, both groups also manifested a population-level bias to keep conspecifics on their left side compared with their right side. Our findings suggest a social processing dominance of the right hemisphere for context-specific social environments. Results are discussed in light of the evolutionary adaptive value of social stimulus as a triggering factor for the manifestation of group-level lateralized behaviors. (PsycINFO Database Record (c) 2016 APA, all rights reserved)
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Tommasi, L., & Vallortigara, G. (2000). Searching for the center: spatial cognition in the domestic chick (Gallus gallus). J Exp Psychol Anim Behav Process, 26(4), 477–486.
Abstract: Chicks learned to find food hidden under sawdust by ground-scratching in the central position of the floor of a closed arena. When tested inan arena of identical shape but a larger area, chicks searched at 2 different locations, one corresponding to the correct distance (i.e., center) in the smaller (training) arena and the other to the actual center of the test arena. When tested in an arena of the same shape but a smaller area, chicks searched in the center of it. These results suggest that chicks are able to encode information on the absolute and relative distance of the food from the walls of the arena. After training in the presence of a landmark located at the center of the arena, animals searched at the center even after the removal of the landmark. Marked changes in the height of the walls of the arena produced some displacement in searching behavior, suggesting that chicks used the angular size of the walls to estimate distances.
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