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Dealing with objects in space: Lateralised mechanisms of perception and cognition in the domestic chick (Gallus gallus)
No full textLateral asymmetries during responses to novel-coloured objects in the domestic chick: A developmental study
No full textApproach direction and accuracy, but not response times, show spatial-numerical association in chicks
Full text linkChicks trained to identify a target item in a sagittally-oriented series of identical items show a
higher accuracy for the target on the left, rather than that on the right, at test when the series
was rotated by 90 ̊. Such bias seems to be due to a right hemispheric dominance in visuospatial tasks. Up to now, the bias was highlighted by looking at accuracy, the measure
mostly used in non-human studies to detect spatial numerical association, SNA. In the present study, processing by each hemisphere was assessed by scoring three variables: accuracy, response times and direction of approach. Domestic chicks were tested under
monocular vision conditions, as in the avian brain input to each eye is mostly processed by
the contralateral hemisphere. Four-day-old chicks learnt to peck at the 4th element in a sagittal series of 10 identical elements. At test, when facing a series oriented fronto-parallel,
birds confined their responses to the visible hemifield, with high accuracy for the 4th element.
The first element in the series was also highly selected, suggesting an anchoring strategy to
start the proto-counting at one end of the series. In the left monocular condition, chicks
approached the series starting from the left, and in the right monocular condition, they
started from the right. Both hemispheres appear to exploit the same strategy, scanning the
series from the most lateral element in the clear hemifield. Remarkably, there was no effect
in the response times: equal latency was scored for correct or incorrect and for left vs. right
responses. Overall, these data indicate that the measures implying a direction of choice,
accuracy and direction of approach, and not velocity, i.e., response times, can highlight
SNA in this paradigm. We discuss the relevance of the selected measures to unveil SNA
Long-term memory for a spatial task in young chicks
No full textTwo-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 com..
Cast shadows allow for solid objects discrimination in newly hatched visually naive chicks (Gallus gallus)
No full textPROCEEDIN
Gravity bias in the interpretation of biological motion by inexperienced chicks
Full text linkOur ability to recognise biological motion in point-light displays
is reduced when the animation sequence is upside-down,
taken as evidence that past experience about direction of
gravity influences the perception of biological motion. We exposed newly hatched chicks, reared in
darkness and thus in the absence of previous visual experience, to point-light animation sequences of a walking hen either upright or upside-down: they responded by aligning their bodies in the apparent direction of motion
in the former situation, but not in the latter, indicating that the vertebrate brain might be predisposed to make assumptions about direction of gravity
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