PT  - JOURNAL ARTICLE
AU  - Irene Susini
AU  - Alexandra Safryghin
AU  - Friederike Hillemann
AU  - Claudia A.F. Wascher
TI  - Delay of gratification in non-human animals: A review of inter- and intra-specific variation in performance
AID  - 10.1101/2020.05.05.078659
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.05.05.078659
4099  - http://biorxiv.org/content/early/2020/05/07/2020.05.05.078659.short
4100  - http://biorxiv.org/content/early/2020/05/07/2020.05.05.078659.full
AB  - The ability to regulate and withhold an immediate behaviour in pursuit of a more advantageous or valuable, albeit delayed, outcome is generally termed ‘self-control’ and is regarded an important cognitive ability enabling adaptive decision-making in both social and asocial contexts. Abilities to cope with a delay in gratification have been investigated in a range of species using a variety of experimental paradigms. The present study attempts a first systematic analysis of available experimental data from non-human animals, to evaluate the effects of experimental design and taxonomic group on performance in delay of gratification tasks. Data were sourced from 52 separate studies and a comprehensive overview of available literature on delay of gratification in non-human animals is presented, identifying a significant lack of socio-ecological diversity across investigated taxa. Both mean percentage of successful waiting trials and maximum endured delay were found to be significantly affected by experimental design, and both measures of waiting performance were independent of taxonomic order. An analysis of data from 25 studies, for which additional individual-level waiting performances were available, identified substantial intra-specific variation in performance. Overall, cross-species comparisons of delay of gratification abilities are hindered by a lack of consistency in experimental designs, and inferences about evolutionary origins of such capacities are unsuitable at present due to the low number of species tested across different orders. Future research on a larger pool of taxa belonging to separate taxonomic groups is encouraged. Research on social and ecological factors causing intra-specific, individual variation in performance should also be considered.Competing Interest StatementThe authors have declared no competing interest.