Long-term memory of relative reward values

Francesca Soldati, Oliver H.P. Burman, Elizabeth A. John, Thomas W. Pike, Anna Wilkinson* (Corresponding Author)

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    21 Citations (Scopus)


    Long-term memory can be adaptive as it allows animals to retain information that is crucial for survival, such as the appearance and location of key resources. This is generally examined by comparing choices of stimuli that have value to the animal with those that do not; however, in nature choices are rarely so clear cut. Animals are able to assess the relative value of a resource via direct comparison, but it remains unclear whether they are able to retain this information for a biologically meaningful amount of time. To test this, captive red-footed tortoises (Chelonoidis carbonaria) were first trained to associate visual cues with specific qualities and quantities of food, and their preferences for the different reward values determined. They were then retested after an interval of 18 months. We found that the tortoises were able to retain the information they had learned about the cues as indicators of relative reward values over this interval, demonstrating a memory for the relative quantity and quality of food over an extended period of time. This is likely to impact directly on an animal's foraging decisions, such as the exploitation of seasonally varying resources, with obvious fitness implications for the individual; however, the implications may also extend to the ecological interactions in which the animal is involved, affecting processes such as herbivory and seed dispersal.
    Original languageEnglish
    Article number20160853
    Number of pages4
    JournalBiology Letters
    Issue number2
    Early online date1 Feb 2017
    Publication statusPublished - Feb 2017

    Bibliographical note

    This study was supported by a studentship awarded to F.S. by the School of Life Sciences, University of Lincoln.

    We thank Bill Hayes, Dawn Simpson and Naomi Mitchell for their help.

    Data Availability Statement

    We provide supporting data in the electronic supplementary material, http://dx.doi.org/10.6084/m9.figshare.c.3664540.


    • foraging decision
    • memory
    • tortoise
    • seed dispersal


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