Biomedical subjects

L Regolin

Publications and source records attributed to L Regolin.

4 recordsLinked to original sources

PubMed1999

Long-term memory for a spatial task in young chicks.

Two-day-old chicks, Gallus gallus domesticus, were faced with a spatial task requiring them to make a detour around a U-shaped barrier in order to join a group of conspecifics placed beyond it. Chicks made one detour trial, and were then retested after delays of 30 min, 3 h and 24 h. When retested, the chicks took significantly less time to make the detour, even at 24 h. Chicks that failed to solve the task on the first trial within the time limit (600 s) took as long as naive chicks, when tested again 24 h later, suggesting that long-term memory for the task requires a form of one-trial learning. Since many chicks chose the same direction of detour on both the first trial and the retest, they may have simply shown a stereotyped preferential response. In a further experiment to test this possibility, we used a more complex version of the apparatus: the direction of detour first chosen by the chick was always blocked, and a subsequent detour in the opposite direction was required to complete the task. This time, chicks did not choose the same direction on the first test and when tested 24 h later. However, they proved able to remember the correct direction for at least 24 h if they were allowed to learn the correct path in a series of five trials. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1999

Detour behaviour, imprinting and visual lateralization in the domestic chick.

Detour behaviour was studied in chicks faced with a vertical-bar barrier behind where an imprinting object (a red ball) was located. Right-eyed chicks took less time to detour the barrier than left-eyed chicks, and binocular chicks showed a bias to detour the barrier on the left side, thus maintaining visual contact with the imprinting object using the lateral field of the right eye, while circling around the barrier. In males, the asymmetries were consistent all along the first two weeks of life, whereas in females they disappeared on days 8 and 11. When tested with a slightly novel version of the original imprinting object (i.e., a ball of a different color), binocular chicks showed a bias to detour the barrier on the right side, thus showing preferential use of the left eye. The same bias occurred when unfamiliar conspecifics were used as goal-objects. Results suggest that cerebral lateralization in birds can directly affect visually-guided motor responses through selective use of the lateral field of vision of the eye contralateral to the hemisphere which has to be put in charge of control of overt behaviour.

Age Factors↗

PubMed1996

Lateral asymmetries due to preferences in eye use during visual discrimination learning in chicks.

Chicks were trained to discriminate between two boxes of the same colour (white) on the basis of their positions using the pecking response. Some chicks were trained to peck at the box on their right side, some at the box on their left side. They were then retrained with two boxes of different colours (one red the other green): in one group of chicks the position of the two boxes was randomly alternated in the various trials (thus making colour a conspicuous but irrelevant cue), in the other it was maintained unchanged. A control group was retrained with two white boxes identical to those used during training. In all of the three groups chicks had to discriminate between the two boxes on the basis of their positions. During training, chicks took less trial and errors to learn when the positive box was placed on their right side and the same occurred during retraining with boxes that maintained a fixed position and during retraining in the control condition. During retraining with position alternation, on the contrary, chicks took less trials and errors to learn when the positive box was placed on their left side. Video recording of the chicks' behaviour while approaching the boxes showed that these lateral asymmetries reflect head and body turning associated to preferences in eye use, likely due to the different specializations of contralateral brain structures. It is argued that position cues engage the right hemisphere, with consequent head turning to the right to allow lateral viewing by the left eye; object-specific cues engage the left hemisphere, with consequent head turning to the left to allow lateral viewing by the right eye.

Animals↗

PubMed1995

Perception of partly occluded objects by young chicks.

Completion of partly occluded objects is a ubiquitous phenomenon in human visual perception. It is unclear, however, whether it occurs at all in other species: Studies on visual discrimination learning have revealed that animals usually attend to parts and features of the discriminative stimuli rather than to global object properties. We provide here the first demonstration of recognition of partly occluded objects in a bird species, the domestic chick Gallus gallus, using the naturalistic setting made available by filial imprinting, a process whereby young birds form attachments to their mothers or some artificial substitute. In Experiment 1, newborn chicks were reared singly with a red cardboard triangle, to which they rapidly imprinted and therefore treated as a social partner. On Day 3 of life, the chicks were presented with pairs of objects composed of either isolated fragments or occluded parts of the imprinting stimulus. Chicks consistently chose to associate with complete or with partly occluded versions of the imprinting object rather than with separate fragments of it. Similarly, in Experiment 2, chicks reared with a partly occluded triangle chose to associate with a complete triangle rather than with fragmented one, whereas chicks reared with a fragmented triangle chose to associate with a fragmented triangle and not with a complete one. Newborn chicks thus appear to behave as if they could experience amodal completion.

Animals↗