Abstract
This study assessed brushtail possums’ performance on the Mechner counting procedure. Six brushtail possums were required to produce different Fixed-Ratio (FR) response targets by lever pressing. Their responses provided access to food reinforcement delivered either upon completing the target FR response requirement on a single lever or, in different conditions, on completing the target FR before producing an additional response on a second lever. The mean number of responses on the first lever before switching to the second lever typically occurred just above the target FR response requirement (FR: 4, 8, 16, 32 and 64). The variability in the number of switches between the levers around the target FR decreased from the first 10 days to the last 10 days, indicating an improvement in counting accuracy over sessions. The time to switch between the first and second lever was consistently variable across response requirements suggesting that it is unlikely the possums were using time to predict when to switch levers. This research further supports the use of the Mechner procedure as a method for measuring counting ability in animals and confirms the possibility of numerical competence in a marsupial species.
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Acknowledgements
The authors would like to thank the students at No. 3 Dairy for helping conduct the experiment and Jenny Chandler and Rob Bakker for their technical expertise and support. This research was conducted following the relevant ethics guidelines and approved by the Waikato Animal Ethics Committee protocol.
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Clarke, K.H., McEwan, J.S., Cameron, K.E. et al. Assessing the performance of brushtail possums (Trichosurus vulpecula) on the Mechner counting procedure. Anim Cogn 25, 1493–1503 (2022). https://doi.org/10.1007/s10071-022-01630-8
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DOI: https://doi.org/10.1007/s10071-022-01630-8