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Ex-situ research in aquariums and zoological settings not only support scientific advancement, they also provide opportunities for education, facilitating both mental and physical stimulation, consequently improving welfare. This study aimed to investigate the impact of cognitive testing on the well-being of a group of male Indo-Pacific bottlenose dolphins. The occurrence of affiliative, aggressive and potentially stereotypical behaviors was assessed based on seven monitored behavior types and compared between "Session days" and "Non-session days." The consistency of the impact was assessed over a three-year period. The analyses revealed that "Play with enrichment," "Affiliative tactile," "Social play" and "Synchronous swim" were significantly higher, while "Aggression" was significantly lower on Session days than on Non-session days. Individual analysis showed significant increase in the positive welfare indicators in all dolphins during Session days. The social network analysis of aggressive interactions between group members also supported an overall decrease of aggression during Session days. These results indicate that dolphin groups that voluntarily participate in cognitive tests under human care benefit from the testing and show an improvement in animal welfare while contributing to scientific advancement.

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Simultaneous interpretation is a complex task that is assumed to be associated with a high workload. To corroborate this association, we measured workload during three tasks of increasing complexity: listening, shadowing, and interpreting, using electroencephalography and self-assessments in four groups of participants with varying experience in simultaneous interpretation. The self-assessment data showed that professional interpreters perceived the most workload-inducing condition, namely the interpreting task, as less demanding compared to the less experienced participants. This higher subjectively perceived workload in non-interpreters was paralleled by increasing frontal theta power values from listening to interpreting, whereas such a modulation was less pronounced in professional interpreters. Furthermore, regarding both workload measures, trainee interpreters were situated between professional interpreters and non-interpreters. Since the non-interpreters demonstrated high proficiencies and exposure in their second language, too, our findings provide evidence for an influence of interpretation training on experienced workload during simultaneous interpretation.

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With the worldwide increase in people speaking more than one language, a better understanding of the behavioural and neural mechanisms governing lexical selection, lexical access in multiple languages and code switching has attracted widespread interest from several disciplines. Previous studies documented higher costs when processing a non-native (L2) than a native (L1) language or when switching from L2 to L1. However, studies on auditory language reception are still scarce and did not take into account the degree of switching experience. Accordingly, in the present study, we combined behavioural and electrophysiological measurements to assess lexical access in L1 and L2 as well as code switching in professional simultaneous interpreters, trainee interpreters, foreign language teachers and Anglistics students, while the participants performed a bilingual auditory lexical decision task. The purpose of this study was to expand the knowledge on code switching in auditory language processing and examine whether the degree of simultaneous interpretation experience might reduce switching costs. As a main result, we revealed that L2 compared to L1 trials, as well as switch compared to non-switch trials, generally resulted in lower accuracies, longer reaction times and increased N400 amplitudes in all groups of participants. Otherwise, we did not reveal any influence of switching direction and interpretation expertise on N400 parameters. Taken together, these results suggest that a late age of L2 acquisition leads to switching costs, irrespective of proficiency level. Furthermore, we provided first evidence that simultaneous interpretation training does not diminish switching costs, at least when focusing on lexical access.

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Alliance formation plays a crucial part in male dolphins' lives. These partnerships may last for decades or even for a lifetime; thus, partner choice and the maintenance of these relationships are both considered key components of alliance formation. In our previous investigations, pairs of adult male dolphins showed a high success rate in cooperative manipulation of a cognitive enrichment device. Here, we introduced two novel cognitive enrichment devices to the group of five dolphins, facilitating simultaneous actions for not only pairs, but for three or even four dolphins. The devices were made of PVC tubes, fittings and caps equipped with rope handles, creating a three-way (T-shape) and a four-way (TT-shape) device. The devices were filled with fish and ice and were designed to be opened by simultaneous pull of the handles. Both devices were tested in 12 trials (each lasted for 15 min), separately. Only one of the caps could be opened, the others were affixed with the position of the openable cap counter-balanced over the trials. Although the dolphins received no training regarding the manipulation of the devices, they were successful in cooperatively opening the three-way devices in 10/12 of trials (70% by two and 30% by three dolphins) and the four-way devices also in 10/12 trials (50% by two, 40% by three and 10% by four dolphins). The dolphins interacted with the devices during the entire testing time, and this was mostly spent in cooperative play (77% and 56% of the test duration with the three-way and four-way device, respectively). The majority of the cooperative play was observed between one particular pair of dolphins that was temporarily associated with a third or sometimes even with a fourth dolphin. These findings demonstrate the first successful use of multi-partner cooperative enrichment devices, providing information on the social organization of a male dolphin group.

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Due to the diversity of the phenomenon, dolphin cooperation has attracted considerable research interest in both wild populations and those under human care. Dolphins cooperate in various contexts, including group hunting, alloparental care, social learning, social play and alliance formation for securing mates. This investigation focused on the effect of group size and partner choice in a cooperative task using systematic group testing. A cooperative enrichment device was made of a PVC tube containing fish and ice that was temporarily sealed with two PVC caps with rope handles attached. The device was designed to be operated by pairs of dolphins, opened by simultaneous pull of its two handles. The analysis focused on two behaviours, cooperative opening and cooperative play with the device. Testing focused on an adult male dolphin group including four to six individuals and using a single or two devices. Altogether five group testing arrangements and a pairwise testing phase were conducted. Out of the six dolphins, five showed active involvement. All ten possible pairs of the five active dolphins were successful in opening and playing with the device cooperatively. Cooperation increased with group size, but the social networks showed no significant differences among group arrangements. However, the cooperative pairs showed a significant difference in success rate during pairwise vs group testing, while demonstrating a strong partner preference. This study provides the first evidence for partner choice with regards to cooperation in male dolphins.

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Social living, long lifespan and advanced cognitive skills provided favourable conditions for the development of pro-social behaviours and cooperative activities in cetacean. Dolphins have been observed to collaborate for various purposes, finding food, finding mates or raising and teaching younger individuals. This study investigated the potential impact of demographic factors (sex and age), social factors (relatedness and group size), and individual experience in a cooperative problem solving task. A cognitive enrichment device was tested with 22 dolphins in 11 group settings. The device consisted of a tube, containing ice and fish, sealed by two caps with rope handles and designed to be operated by pairs of dolphins. The investigation focused on the differences in trial outcome (success rate of cooperative opening of the device) and on cooperative play (dolphin pairs engaging in synchronous swim with the device). From the five potential factors, sex showed the highest impact. Cooperative openings were more than four times more frequent in males than in females (75% vs 17%, respectively), and cooperative play was exclusively displayed by adult males. Given the strong correlation between cooperative opening and cooperative play, we argue the two behaviours can be regarded as parts of a cooperative action chain. This study provides the first evidence for intersexual differences in collaborative actions in dolphins under systematic testing conditions.

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