Different memory systems in food-hoarding birds: A response to Pravosudov by Smulders TV, Read JCA, SmuldersRead2024.pdf (0.5 MiB) - We recently showed that food-hoarding birds use familiarity processes more than recollection processes when remembering the spatial location of their caches (Smulders et al., Animal Cognition 26:1929-1943, 2023). Pravosudov (Learning & Behavior, https://doi.org/ https://doi.org/10.3758/s13420-023-00616-x , 2023) called our findings into question, claiming that our method is unable to distinguish between recollection and familiarity, and that associative learning tasks are a better way to study the memory for cache sites. In this response, we argue that our methods would have been more likely to detect recollection than familiarity, if Pravosudov's assertions were correct. We also point out that associative learning mechanisms may be good for building semantic knowledge, but are incompatible with the needs of cache site memory, which requires the unique encoding of caching events.
Hoarding titmice predominantly use Familiarity, and not Recollection, when remembering cache locations by Smulders TV, Douglas LJ, Reza D, Male LH, Prysce A, Alix A, de GuzmanDodd A, Read JCA, SmuldersDouglasRezaMalePrysceAlixDoddRead2023.pdf (1.8 MiB) - Scatter-hoarding birds find their caches using spatial memory and have an enlarged hippocampus. Finding a cache site could be achieved using either Recollection (a discrete recalling of previously experienced information) or Familiarity (a feeling of "having encountered something before"). In humans, these two processes can be distinguished using receiver operating characteristic (ROC) curves. ROC curves for olfactory memory in rats have shown the hippocampus is involved in Recollection, but not Familiarity. We test the hypothesis that food-hoarding birds, having a larger hippocampus, primarily use Recollection to find their caches. We validate a novel method of constructing ROC curves in humans and apply this method to cache retrieval by coal tits (Periparus ater). Both humans and birds mainly use Familiarity in finding their caches, with lower contribution of Recollection. This contribution is not significantly different from chance in birds, but a small contribution cannot be ruled out. Memory performance decreases with increasing retention interval in birds. The ecology of food-hoarding Parids makes it plausible that they mainly use Familiarity in the memory for caches. The larger hippocampus could be related to associating cache contents and temporal context with cache locations, rather than Recollection of the spatial information itself.
Stereopsis in animals: evolution, function and mechanisms by Nityananda V, Read JCA, NityanandaRead2017.pdf (0.8 MiB) - Stereopsis is the computation of depth information from views
acquired simultaneously from different points in space. For many
years, stereopsis was thought to be confined to primates and other
mammals with front-facing eyes. However, stereopsis has now been
demonstrated in many other animals, including lateral-eyed prey
mammals, birds, amphibians and invertebrates. The diversity of
animals known to have stereo vision allows us to begin to investigate
ideas about its evolution and the underlying selective pressures in
different animals. It also further prompts the question of whether all
animals have evolved essentially the same algorithms to implement
stereopsis. If so, this must be the best way to do stereo vision, and
should be implemented by engineers in machine stereopsis.
Conversely, if animals have evolved a range of stereo algorithms in
response to different pressures, that could inspire novel forms of
machine stereopsis appropriate for distinct environments, tasks or
constraints. As a first step towards addressing these ideas, we here
review our current knowledge of stereo vision in animals, with a view
towards outlining common principles about the evolution, function
and mechanisms of stereo vision across the animal kingdom. We
conclude by outlining avenues for future work, including research into
possible new mechanisms of stereo vision, with implications for
machine vision and the role of stereopsis in the evolution of
camouflage.
Unravelling the illusion of flicker fusion by Umeton D, Read JCA, Rowe C, UmetonReadRowe2017.pdf (0.7 MiB) - For over 150 years, researchers have investigated the anti-predator function of animal patterns. However, this work has mainly focused on when prey remain still, and has only recently started to incorporate motion into the study of defensive coloration. As motion breaks camouflage, a new challenge is to understand how prey avoid predators while moving around their environment, and if a moving prey can ever be camouflaged. We propose that there is a solution to this, in that a ‘flicker fusion effect’ can change the appearance of the prey in the eyes of their predators to reduce the chances of initial detection. This effect occurs when a high contrast pattern blurs at speed, changing the appearance of the prey, which may help them better match their background. Despite being widely discussed in the literature, the flicker fusion effect is poorly described, there is no clear theoretical framework for testing how it might reduce predation, and the terminology describing it is, at best, rather confusing. Our review addresses these three key issues to enable researchers to formulate precise predictions about when the flicker fusion effect occurs, and to test how it can reduce predation.
The contrast sensitivity function of the praying mantis Sphodromantis lineola by Nityananda V, Tarawneh G, Jones L, Busby N, Herbert W, Davies R, Read JCA , NityanandaTarawnehJonesEARead2015.pdf (2.6 MiB)