Does the chimpanzee have a theory of mind? 30 years later

On the 30th anniversary of Premack and Woodruff's seminal paper asking whether chimpanzees have a theory of mind, we review recent evidence that suggests in many respects they do, whereas in other respects they might not. Specifically, there is solid evidence from several different experimental paradigms that chimpanzees understand the goals and intentions of others, as well as the perception and knowledge of others. Nevertheless, despite several seemingly valid attempts, there is currently no evidence that chimpanzees understand false beliefs. Our conclusion for the moment is, thus, that chimpanzees understand others in terms of a perception-goal psychology, as opposed to a full-fledged, human-like belief-desire psychology.     

Prospective object search in dogs: mixed evidence for knowledge of <Emphasis Type="Italic">What</Emphasis> and <Emphasis Type="Italic">Where</Emphasis>

We investigated whether two dogs that had been specially trained to retrieve objects by their names were able to integrate information about the identity (What) as well as the location (Where) of those objects so that they could plan their search accordingly. In a first study, two sets of objects were placed in two separate rooms and subjects were asked to retrieve the objects, one after the other. Both dogs remembered the identity of the objects as they reliably retrieved the correct objects. One of the dogs was also able to integrate information about the object’s location as he chose the correct location in which the object had been placed. Further investigation of the second dog’s behavior revealed that she followed a more stereotyped search strategy. Despite this variation in performance, this study provides evidence for the memory of What and Where in a domestic dog and shows the prospective use of such information in a search task.     

The effects of endowment on the demand for probabilistic information

Research shows that individuals are ambiguity averse: they choose unambiguous over equivalent ambiguous prospects and price them higher (either as buyers or sellers). Moreover, it is often assumed that ambiguity averse individuals are willing to pay an ambiguity premium for information that reduces ambiguity [Camerer, C. F., & Weber, M. (1992). Recent developments in modeling preferences: Uncertainty and ambiguity. Journal of Risk and Uncertainty, 5(4), 325–370]. However, when people are asked to exchange an ambiguous alternative in their possession for an equivalent unambiguous one, they prefer to retain the former [Roca, M., Hogarth, R. M., & Maule, A. J. (2006). Ambiguity seeking as a result of the status quo bias. Journal of Risk and Uncertainty, 32(3), 175–194]. We present three experiments investigating the economic effects of endowment on attitudes towards ambiguity and the ambiguity premium. The experiments, based on a [Becker, G., DeGroot, M., & Marschak, J. (1964). Measuring utility by a single-response sequential method. Science, 9, 3] procedure, show that the value attributed to ambiguity reducing information is substantially affected by the status quo of the individual.     

Great apes’ capacities to recognize relational similarity

Recognizing relational similarity relies on the ability to understand that defining object properties might not lie in the objects individually, but in the relations of the properties of various object to each other. This aptitude is highly relevant for many important human skills such as language, reasoning, categorization and understanding analogy and metaphor. In the current study, we investigated the ability to recognize relational similarities by testing five species of great apes, including human children in a spatial task. We found that all species performed better if related elements are connected by logico-causal as opposed to non-causal relations. Further, we find that only children above 4 years of age, bonobos and chimpanzees, unlike younger children, gorillas and orangutans display some mastery of reasoning by non-causal relational similarity. We conclude that recognizing relational similarity is not in its entirety unique to the human species. The lack of a capability for language does not prohibit recognition of simple relational similarities. The data are discussed in the light of the phylogenetic tree of relatedness of the great apes.     

A competitive nonverbal false belief task for children and apes

A nonverbal false belief task was administered to children (mean age 5 years) and two great ape species: chimpanzees (Pan troglodytes) and bonobos (Pan paniscus). Because apes typically perform poorly in cooperative contexts, our task was competitive. Two versions were run: in both, a human competitor witnessed an experimenter hide a reward in one of two containers. When the competitor then left the room (version A) or turned around (version B), the experimenter switched the locations of the containers. The competitor returned and reached with effort, but unsuccessfully, towards the incorrect container. Children displayed an understanding of the competitor's false belief by correctly choosing the other container to find the reward. Apes did not. However, in version A (but not version B), apes looked more often at the unchosen container in false belief trials than in true belief control trials, possibly indicating some implicit or uncertain understanding that needs to be investigated further.     

Beliefs in Equality for Women and Men as Related to Economic Factors in Central and Eastern Europe and the United States

Do economic indicators predict the general level of support for gender equality? This question was investigated in a sample of countries in Central and Eastern Europe, a region that has been undergoing rapid economic changes since the early 1990s. In this overall sample of male and female college students from ten countries, including the United States as a comparison, the predicted association between stronger beliefs in gender role egalitarianism and positive economic factors was generally supported. Also, consistent with other research, women were more in support of gender equality than men were. There was no support for a predicted trend in less support for gender equality over the time period of the present study.     

Mangabeys (<Emphasis Type="Italic">Cercocebus torquatus lunulatus</Emphasis>) solve the reverse contingency task without a modified procedure

Problem solving often relies on generating new responses while inhibiting others, particularly prepotent ones. A paradigm to study inhibitory abilities is the reverse contingency task (Boysen and Berntson in J Exp Psychol Anim Behav Process 21:82–86, 1995), in which two different quantities of food are offered to an individual who receives the array he did not choose. Therefore, mastery of the task demands selecting the smaller quantity to obtain the larger one. Several non-human primates have been tested in the reverse contingency task. To date, only great apes and rhesus monkeys (Macaca mulatta) have succeeded in the original task, with no need of procedural modifications as the large-or-none contingency, correction trials or symbolic stimuli substituting for actual food quantities. Here, four mangabeys were presented with two stimulus arrays of one and four raisins in the context of the reverse contingency task. Three of them learned to perform the task well above chance without a modified procedure. They also reached above-chance performance when presented with two stimulus arrays of zero and four raisins, despite the initial difficulty of choosing a null quantity. After a period of 7–10 months, in which the animals were not tested on any task, all three subjects continued to perform well, even when presented with novel quantity pairs.     

Translation and Validation of the French Version of the Revised Green et al., Paranoid Thoughts Scale (R-GPTS) in Two Samples: Non-Clinical and Clinical Adults

Paranoia consists of unfounded beliefs that harm will be caused with intent to hurt the subject. Paranoid thoughts exist on a continuum of severity from severe forms in several psychological pathologies to milder forms in a significant minority of individuals of the general population (Freeman, 2007). It can be measured using several types of questionnaires. One recent questionnaire that measures paranoia in both clinical and non-clinical populations is the revised Green et al., Paranoid Thoughts Scale (R-GPTS) (Freeman et al., 2019). This questionnaire is an improved version of the Green et al., Paranoid Thoughts Scale (GPTS) (Green et al., 2008) and has excellent psychometric properties. In the present study, the R-GPTS was translated into French and the psychometric properties of the new French version were evaluated in a sample of the general population (N = 600) and in a clinical sample (N = 22). Confirmatory factor analysis supported the original two-factor structure (social reference and persecution subscales) of the R-GPTS. Evidence of excellent internal consistency of the R-GPTS was found. Furthermore, good convergent and discriminant validity was also found. Test-retest reliability showed significant positive correlations over a 1-month period. The findings discussed above were found in the non-clinical sample. Lastly, the R-GPTS revealed good preliminary criterion validity established from the comparison between the clinical and the non-clinical groups. In conclusion, the French version of the R-GPTS is a valid and reliable tool to measure paranoia in the general population. Due to the small sample size of the clinical sample, further studies are needed in order to confirm good psychometric properties in clinical populations, even though our preliminary findings are promising.     

Beyond Rasiowa's Algebraic Approach to Non-classical Logics

This paper reviews the impact of Rasiowa's well-known book on the evolution of algebraic logic during the last thirty or forty years. It starts with some comments on the importance and influence of this book, highlighting some of the reasons for this influence, and some of its key points, mathematically speaking, concerning the general theory of algebraic logic, a theory nowadays called Abstract Algebraic Logic. Then, a consideration of the diverse ways in which these key points can be generalized allows us to survey some issues in the development of the field in the last twenty to thirty years. The last part of the paper reviews some recent lines of research that in some way transcend Rasiowa's approach. I hope in this way to give the reader a general view of Rasiowa's key position in the evolution of Algebraic Logic during the twentieth century. This paper is an extended version of the invited talk given by the author at the conference Trends in Logic III, dedicated to the memory of A. MOSTOWSKI, H. RASIOWA and C. RAUSZER, and held in Warsaw and Ruciane-Nida from 23rd to 25th September 2005. Presented by Jacek Malinowski