Corvid Re-Caching without ‘Theory of Mind’: A Model

Scrub jays are thought to use many tactics to protect their caches. For instance, they predominantly bury food far away from conspecifics, and if they must cache while being watched, they often re-cache their worms later, once they are in private. Two explanations have been offered for such observations, and they are intensely debated. First, the birds may reason about their competitors' mental states, with a ‘theory of mind’; alternatively, they may apply behavioral rules learned in daily life. Although this second hypothesis is cognitively simpler, it does seem to require a different, ad-hoc behavioral rule for every caching and re-caching pattern exhibited by the birds. Our new theory avoids this drawback by explaining a large variety of patterns as side-effects of stress and the resulting memory errors. Inspired by experimental data, we assume that re-caching is not motivated by a deliberate effort to safeguard specific caches from theft, but by a general desire to cache more. This desire is brought on by stress, which is determined by the presence and dominance of onlookers, and by unsuccessful recovery attempts. We study this theory in two experiments similar to those done with real birds with a kind of ‘virtual bird’, whose behavior depends on a set of basic assumptions about corvid cognition, and a well-established model of human memory. Our results show that the ‘virtual bird’ acts as the real birds did; its re-caching reflects whether it has been watched, how dominant its onlooker was, and how close to that onlooker it has cached. This happens even though it cannot attribute mental states, and it has only a single behavioral rule assumed to be previously learned. Thus, our simulations indicate that corvid re-caching can be explained without sophisticated social cognition. Given our specific predictions, our theory can easily be tested empirically

The evolution of financial accounting in Portugal since the 1960s : a new institutional economics perspective

Using a new institutional economics perspective, this article analyses the economic and political context that led to accounting standardisation in Portugal from 1977 onwards and to the recent adoption of the International Financial Reporting Standards (IFRS). The process of accounting standardisation was related to the tax reform of 1963. Additionally, evidence was found that there were also political pressures related to the need to improve the national systems of accounts. The lack of development of the accounting profession and the emphasis on legality substantiated the need for enforcement in the law in 1977 of a standardised accounting plan that was similar to other plans in Europe, namely the French Plan. In a legalist country like Portugal, the modelling of national standards on the international ones and the definitive adoption of adapted IFRS in 2010 by unlisted companies had to be complemented by the enactment in law of the accounting regulations.Fundação para a Ciência e a Tecnologia (FCT

Wild orangutan males plan and communicate their travel direction one day in advance

The ability to plan for the future beyond immediate needs would be adaptive to many animal species, but is widely thought to be uniquely human. Although studies in captivity have shown that great apes are capable of planning for future needs, it is unknown whether and how they use this ability in the wild. Flanged male Sumatran orangutans (Pongo abelii) emit long calls, which females use to maintain earshot associations with them. We tested whether long calls serve to communicate a male's ever-changing predominant travel direction to facilitate maintaining these associations. We found that the direction in which a flanged male emits his long calls predicts his subsequent travel direction for many hours, and that a new call indicates a change in his main travel direction. Long calls given at or near the night nest indicate travel direction better than random until late afternoon on the next day. These results show that male orangutans make their travel plans well in advance and announce them to conspecifics. We suggest that such a planning ability is likely to be adaptive for great apes, as well as in other taxa

Bonobos and orangutans, but not chimpanzees, flexibly plan for the future in a token-exchange task

International audienceNon-human animals, including great apes, have been suggested to share some of the skills for planning that humans commonly exhibit. A crucial difference between human and non-human planning may relate to the diversity of domains and needs in which this skill is expressed. Although great apes can save tools for future use, there is little evidence yet that they can also do so in other contexts. To investigate this question further, we presented the apes with a planning token-exchange task that differed from standard tool-use tasks. Additionally, we manipulated the future outcome of the task to investigate planning flexibility. In the Exchange condition, subjects had to collect, save and transport tokens because they would need them 30 min later to exchange them for food with a human, i.e., ''bring-back'' response. In the Release condition, the collection and transport of tokens were not needed as no exchange took place after 30 min. Out of 13 subjects, eight solved the task at least once in the Exchange condition, with chimpanzees appearing less successful than the other species. Importantly, three individuals showed a clear differential response between conditions by producing more ''bring-back'' responses in the Exchange than in the Release conditions. Those bonobo and orangutan individuals hence adapted their planning behavior according to changing needs (i.e., they brought tokens back significantly more often when they would need them). Bonobos and orangutans, unlike chimpanzees, planned outside the context of tool-use, thus challenging the ide

Chimpanzees strategically manipulate what others can see

Humans often strategically manipulate the informational access of others to their own advantage. Although chimpanzees know what others can and cannot see, it is unclear whether they can strategically manipulate others’ visual access. In this study, chimpanzees were given the opportunity to save food for themselves by concealing it from a human competitor and also to get more food for themselves by revealing it to a human cooperator. When knowing that a competitor was approaching, chimpanzees kept more food hidden (left it covered) than when expecting a cooperator to approach. When the experimenter was already at the location of the hidden food, they actively revealed less food to the competitor than to the cooperator. They did not actively hide food (cover up food in the open) from the competitor, however. Chimpanzees thus strategically manipulated what another could see in order to maximize their payoffs and showed their ability to plan for future situations