ABSTRACT. Mother-infant cannibalism in species of galagos as in several other species of nonhuman primates is a common phenomenon. In non-human primates kept in laboratory conditions many of the observed cases of cannibalism were not associated with starvation and with infanticide. Cannibalism in galagos was observed in at least five different species. In several laboratories, like the Duke University Primate Center, the frequencies of cannibalism in galagos species in captivity have been reduced by the isolation of pregnant female before the parturition from her companions, especially adult males.At the Primate Behaviour Research Group (University of Witwatersrand, Johannesburg, South Africa) three cases of cannibalism were observed in two Galago crassicaudatus umbrosus' mothers before the end of the third day after birth. To understand the reasons why the mothers cannibalize their own infants, it was decided to analyze the mother-infant interaction which preceded the death of the infants.In Galago crassicaudatus twin and triplet births are very common. In one of our two observed mothers who cannibalized their infants, there was one triplet birth. In this study the two pregnant females were isolated in two separated cages ten days before giving birth. One of the two observed mothers gave birth to triplets, the other had a single birth. At the end all four infants were cannibalized. In all cases the cannibalization started after the infant's death. The infants' deaths were caused by lack of maternal care which caused them to starve. The results show that the triplet's mother differed in some of her behaviour towards her infants. In one of the cannibalized infants behaviours such as Nipple and Mother Passive Prevent were never seen before death. In our cases it seems that cannibalism was probably due to the laboratory condition that for generation to generation caused stress to the mothers and changed their maternal behaviours, which lead to the death of the offspring which after death became a consumable resource.
The cognitive "Bignetti Model" (TBM) thoroughly discussed elsewhere, shares a strong analogy with "Learning Through Experience" (LTE) and Bayesian Learning Process (BLP). Here, TBM's theory is challenged by means of a psychophysical press/no-press decision task (DT). Participants must press a computer key in response to sweet food image (SWEET) or refrain from doing it with a salted food image (SALTED) (24 trials each, mixed at random in a 48-trial DT). Reaction times (RT) plotted as a function of trials decrease exponentially according to a well-known "intertrial priming" effect. When 1 SWEET is repeated 24 times per DT, RTs tend to a minimal value that corresponds to the fastest, instinctive RT the participant can exhibit when engaged in a traffic light-based task. Interestingly, the more we change SWEET images, the greater are the final RTs in a DT (this disturbance is not seen by changing SALTED images). It is proposed that the increase of motivational incentives along the task may foster the learning process. In the presence of SWEET distractors this process is impaired due to a short-term memory mismatch between increasing targets of similar semantics. These results are compatible both with the current literature and TBM.
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