A leftward bias negatively correlated with performance is selectively displayed by domestic chicks during rule reversal (not acquisition)

ABSTRACT

In order to face a constantly changing environment, animals need to be able to update their knowledge of the world on the basis of new information. Often, this means to inhibit a previously acquired response and flexibly change their behaviour to produce a new response. Here, we measured such abilities in young domestic chicks, employing a Colour Reversal Learning Task. During the acquisition phase, 17 one-week-old male chicks had to learn to peck on one of two coloured boxes to obtain a food reward. After reaching criterion, chicks underwent a reversal phase in which the previously learned colour-reward contingency was swapped. As expected from the literature, chicks performed better in the acquisition phase with respect to the reversal phase. Results moreover highlighted the presence of a lateralized bias selectively during reversal: chicks performed better if the stimulus rewarded was located in the left hemispace (processed by the right hemisphere). Interestingly, the bias correlated with the individual difficulty, i.e., it was stronger in those chicks which needed more trials to complete the reversal session. The present study contributes evidence in support of behavioural flexibility in young chicks, along with a novel perspective on lateralized mechanisms that might underlie such ability.

KEYWORDS:

• Reversal learning
• domestic chicks
• spatial bias
• behavioural flexibility
• right hemispheric dominance

Acknowledgements

This work was carried out within the scope of the project “use-inspired basic research”, for which the Department of General Psychology of the University of Padova has been recognized by the Italian Ministry of University and Research as “Department of Excellence” for the period 2018–2022. L.R. designed the study and performed the experiments; M.L. analysed the data; all authors discussed and interpreted the results; M.L. wrote the paper and created the figures; S.P. and L.R. critically reviewed the paper. This study was realized in compliance with the Italian and the European Community laws concerning animal research and treatment. All the procedures employed in the study were examined and approved by the Ethical Committee of the University of Padua (Comitato Etico di Ateneo per la Sperimentazione Animale—C.E.A.S.A).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.

Additional information

Funding

This research has been supported by PRIN 2017 ERC-SH4–A grant (2017PSRHPZ) to L.R. M.L. is sponsored by a PhD scholarship funded by the CARIPARO Foundation.