University of Konstanz
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Gaze following in pigeons increases with the number of demonstrators
No full textGaze following, orienting one’s gaze in the same direction as another individual, is a key component of social attention across species, and expected to play an important role in group contexts. To investigate its collective dimension, this study tested whether the number of conspecifics providing a gaze cue influences gaze following in pigeons (Columba livia). Using motion capture to track fine-scale head and body movements, we presented attention-getting stimuli to subsets of pigeons (demonstrators), while others (observers) could not see them. Observer pigeons followed the gaze of demonstrators, specifically toward the target object rather than a perceptually similar distractor, and the frequency increased with the number of demonstrators. We found no evidence for nonlinear effects under our experimental conditions. In group-living species like pigeons, multiple individuals looking in the same direction may serve as a more reliable social signal, highlighting the critical role of collective context in animal social cognition.publishe
Growing on patch boundaries of heterogeneous soils promotes root growth but not the total biomass of naturalized alien and native plants
No full textBackground and aims: Soil heterogeneity has been found to promote plant invasion, as many naturalized alien species benefit more from nutrient-rich patches than native species do. However, it remains unclear whether naturalized alien species also benefit more from growing on patch boundaries than from growing in the patch centres of heterogeneous soils.
Methods: We experimentally tested whether the planting position changes the effect of soil heterogeneity on the growth of native and naturalized alien plants. We created pots with heterogeneous soils consisting of patches of sand, peat-based potting substrate (peat) and a 1:1 sand-peat mixture, and homogenous soils consisting of the mixture only. In each pot, we planted three plants of one of five native or five naturalized alien species, either on the boundaries between or in the centres of the soil patches. Results: Individual plant growth increased when the plant had direct access to the peat patches. This positive effect of peat on plant growth tended to be more pronounced for the naturalized alien species than for the natives. The populations of naturalized alien species also tended to benefit more, in terms of total biomass, from soil heterogeneity than the natives did. Belowground biomass of the plant populations, was not significantly affected by soil heterogeneity, but was larger when plants grew on the patch boundaries instead of in the centres.
Conclusion: Our study suggests that soil heterogeneity promotes the growth of naturalized alien plants over native plants. Moreover, being positioned on the boundary of strongly contrasting patches might provide benefits to plant growth.publishe
Zero-temperature phase-flip rate in a biased parametric oscillator
No full textA parametrically driven oscillator has two stable vibrational states at half the modulation frequency. The states have opposite phases and equal amplitudes. An extra drive at half the modulation frequency provides an effective bias that lifts the state symmetry. Quantum fluctuations lead to switching between the states, i.e., to phase-flip transitions. We develop a semiclassical approach that allows us to find the dependence of the switching rates on the amplitude of the bias and the parameters of the modulating field. We find that the rate of switching from a “shallow” state can become anomalously small at certain parameter values, leading to an efficient localization in this state. This is a consequence of the change of the topology of the oscillator phase trajectories. The results pave the way for implementing nonreciprocal quantum Ising systems based on parametric oscillators.publishe
Re-evaluating adenosine-nucleoside polyphosphate levels in human cells by mass spectrometry
No full textpublishe
Microbial plankton uptake enhances the degradation of a biodegradable microplastic
No full textThe use of biodegradable plastics as an alternative to conventional non-degradable synthetic polymers is gaining market to reduce plastic pollution, however, their biodegradability is not unconditional. In this study, we hypothesized that planktonic protists (nanoflagellates and ciliates) increase the degradation of the biodegradable PLGA (poly(lactic-co-glycolic) acid) due to particle uptake. We conducted uptake and degradation experiments using PLGA microspheres of 4.9 ± 2.8 μm diameter and the microbial planktonic community from the Baltic Sea. We found that planktonic protists ingested PLGA of different sizes, with ciliates displaying higher clearance rates and ingesting larger particles compared to nanoflagellates. In addition, we observed a more pronounced decrease in PLGA concentration and particle size over time in the presence of seawater containing microbial plankton compared to a control with only ultrapure water, suggesting that the presence of these organisms increases the rate of degradation of PLGA in marine ecosystems. Altogether, these results indicate that microbial plankton enhances the degradation of biodegradable microplastics like PLGA, specifically through rapid uptake by planktonic protists. These findings highlight the role of particle ingestion by planktonic protists in the fate of the so-called biodegradable plastics when they enter aquatic ecosystems.publishe
Multisession transcranial direct current stimulation and aerobic exercise synergistically improve food craving symptoms, impulsivity, and cognitive flexibility in women with overweight and obesity : a randomized controlled trial
No full textBackground: We explored the potential synergistic effects of combining multisession anodal transcranial direct current stimulation (a-tDCS) with chronic aerobic exercise (AE) on food cravings (FC), impulsivity (IMP), risky decision-making (RDM), and cognitive flexibility (CF) in women with overweight or obesity exhibiting food craving symptoms.
Methods: Thirty-six women with overweight or obesity and symptoms of food craving (age: 26±6,4 years) were randomly allocated into three groups using permuted block randomization (n = 12 each): (1) a-tDCS + AE, (2) Sham + AE, and (3) Control (no intervention). During Phase 1, the a-tDCS + AE group received five consecutive sessions of a-tDCS, while the Sham + AE group received sham tDCS. In Phase 2, both the a-tDCS + AE and Sham + AE groups completed three sessions of moderate-intensity continuous aerobic exercise per week for four weeks. Outcome measures, including food cravings (FC) and cognitive flexibility (CF), were assessed at baseline, after five days of tDCS, and after four weeks of AE. Follow-up measurements for FC and CF were also conducted one month post-intervention.
Results: FC was lower in the a-tDCS + AE group compared to Sham + AE and Control groups in Phase 1 (Cohen’s d = 1.4 and 1.9, respectively). In Phase 2, a-tDCS + AE and Sham + AE groups showed lower FC than the Control group (d = 3.8 and d = 2.8, respectively), and a-tDCS + AE also showed a lower FC compared to the Sham + AE group (d = 1.5). FC remained lower in the a-tDCS + AE group compared to Sham + AE and Control groups at follow-up (d = 1.7 and d = 2.4, respectively). CF was higher in the a-tDCS + AE compared to Sham + AE and Control groups (d = 2.1 and d = 1.4, respectively) and in the sham + AE (d = 1.0) compared to control in Phase 2. At follow-up, CF was higher only in the a-tDCS + AE group compared to the Control (d = 1.2). IMP scores were higher in the a-tDCS + AE group compared to the other groups in Phases 1 (d = 1.0 and d = 1.4) and 2 (d = 5.4 and d = 1.9). RDM was higher in the a-tDCS + AE compared to the Control group in phase 2 (d = 1.3).
Conclusions: Multisession a-tDCS combined with four weeks of moderate AE synergistically reduces food cravings and improves related variables to a greater extent than AE alone, with sustained effects, in women with overweight or obesity and symptoms of food craving.
Trial registration: This study was registered in the Iranian Registry of Clinical Trials (IRCT id: IRCT20210617051606N7; Registration date: 04.02.2023).publishe
Virtual Reality experiments in the field
No full textVirtual Reality (VR) has paved its way into experimental psychology due to its capacity to realistically simulate real-world experiences in a controlled way. Theoretically, this technology opens the possibility to conduct experiments anywhere in the world using consumer hardware (e.g. mobile-VR). This would allow researchers to access large scale, heterogeneous samples and to conduct experiments in the field in cases where social distancing is required – e.g. during the COVID-19 pandemic. Here, we investigate the feasibility of carrying VR experiments in the field using mobile-VR through a stress inductive (public speaking task) and a relaxation (nature) task and contrast them with results in the laboratory (HTC Vive and mobile-VR). The first experiment employed a 2 (device: HTC Vive Pro (HMD) versus Wearality Sky VR smartphone adapter) x 3 (audience: ‘none’, ‘attentive’, ‘inattentive’) between-subjects design. Thirty-four participants took part in the experiment and completed a public speaking task. No significant difference was detected in participants’ sense of presence, cybersickness, or stress levels. In the second experiment, using an inexpensive Google Cardboard smartphone adapter a 3 (between: device setting) x 2 (within: task) mixed-design was employed. Sixty participants joined the experiment, and completed a public speaking and a nature observation task. No significant difference in participants’ sense of presence, cybersickness, perceived stress and relaxation were detected. Taken together, our results provide initial evidence supporting the feasibility and validity of using mobile VR in specific psychological field experiments, such as stress induction and relaxation tasks, conducted in the field. We discuss challenges and concrete recommendations for using VR in field experiments. Future research is needed to evaluate its applicability across a broader range of experimental paradigms.publishe
Adverse reactions to the use of large language models in social interactions
No full textLarge language models (LLMs) are poised to reshape the way individuals communicate and interact. While this form of AI has the potential to efficiently make many human decisions, there is limited understanding of how individuals will respond to its use in social interactions. In particular, it remains unclear how individuals interact with LLMs when the interaction has consequences for other people. Here, we report the results of a large-scale, preregistered online experiment (n = 3,552) showing that human players’ fairness, trust, trustworthiness, cooperation, and coordination in economic two-player games decrease when the decision of the interaction partner is taken over by ChatGPT. On the contrary, we observe no adverse reactions when individuals are uncertain whether they are interacting with a human or a LLM. At the same time, participants often delegate decisions to the LLM, especially when the model’s involvement is not disclosed, and individuals have difficulty distinguishing between decisions made by humans and those made by AI.publishe
Developmental neurotoxicity (DNT) : A call for implementation of new approach methodologies for regulatory purposes: Summary of the 5th International Conference on DNT Testing
No full textThe 5th International Conference on Developmental Neurotoxicity (DNT) Testing (DNT5) took place in April 2024 in Konstanz, Germany, organized by CAAT-Europe, the University of Konstanz, and scientists from the US EPA, SCAHT, and CAAT at Johns Hopkins University Bloomberg School of Public Health. The conference convened experts from regulatory agencies, industry, and academia to explore the latest advancements in DNT testing and the integration of animal-free new approach methodologies (NAMs) into next-generation risk assessment (NGRA). The key topic was the application and further development of the recently established DNT in vitro test battery (DNT-IVB). To support this, OECD held a satellite meeting to discuss necessary next steps for further implementation of the DNT-IVB in regulatory contexts. Validation of new DNT test methods and use of their data for in-vitro-to-in-vivo extrapolations in physiologically based kinetic models were also important themes of the main meeting. In this context, the question was raised when a comprehensive biological and chemical coverage by the DNT-IVB would be reached. A need for additional testing data was recognized. Context-specific validation approaches for the entire DNT-IVB and the potential for intelligent combinations of assays to enhance the predictive power of the test battery were also addressed. Many presentations demonstrated the field’s embrace of novel developments, including the use of multi-endpoint embryonic zebrafish tests, the development of artificial intelligence-driven computational approaches, and the establishment of complex, electrically active brain organoids and other self-organizing structures. Through its highly interactive format, DNT5 promoted extensive collaborative efforts in advancing the field toward more human-relevant, scientifically reliable, and ethical toxicological assessments.publishe
Effect of sweet and caloric drinks on cardiac reactivity to slow-paced breathing in healthy adults
No full textCardiac reactivity is proposed to be a central indicator of autonomic functioning. While hyperglycemia plays a limited role in cardiac stress reactivity, it is unclear whether it may modulate cardiac reactivity in non-stressful situations. We investigated the effect of glucose on cardiac reactivity to a relaxing exercise, namely, slow-paced breathing (SPB). A total of 115 adults (age mean = 23.28 years, SD = 6.88; 76% female) either consumed a sweet & caloric , a sweet , a caloric drink , or pure water after baseline. Later, they performed a sustained attention test and SPB. Electrocardiography and impedance cardiography was obtained, and blood glucose and subjective relaxation were measured repeatedly. We analyzed changes in parasympathetic (root mean square of successive differences [RMSSD]) and sympathetic (pre-ejection period [PEP]) cardiac activity and subjective relaxation using growth curve models and performed correlational analyses. Hyperglycemia triggered cardiac PNS withdrawal and SNS activation. Despite this, SPB increased cardiac PNS activity and subjective relaxation and decreased cardiac SNS activity in all groups. Our results align with the autonomic space model and highlight the tight link between autonomic regulation and blood glucose homeostasis. Hyperglycemia might play a limited modulating role in cardiac reactivity to slow-paced breathing.publishe