Raising the level: orangutans solve the floating peanut task without visual feedback.

Chimpanzees and orangutans are able to generate innovative behaviors to solve complicated physical problems. For example, when presented with an out-of-reach peanut at the bottom of a vertical tube (floating peanut task-FPT), some of them spontaneously spit water into the tube until the peanut floats to the top. Yet, it is unclear whether this innovative solution results from repeating those actions that bring the peanut incrementally closer to the top or from anticipating the solution before acting. In the current study, we addressed this question by presenting three naïve orangutans with an opaque version of the FPT that prevented them from obtaining visual information about the effect of their actions on the position of the peanut. One of the subjects solved the opaque FPT in the very first trial: he collected water from the faucet and poured it into the opaque tube repeatedly until the hitherto non-visible peanut reached the top. This provides evidence for the first time that orangutans can potentially solve the FPT without relying on sensorimotor learning, but to some extent by mentally representing the problem.

No evidence of what-where-when memory in great apes (Pan troglodytes, Pan paniscus, Pongo abelii, and Gorilla gorilla).

Episodic memory is the ability to recollect specific past events belonging to our personal experience, and it is one of the most crucial human abilities, allowing us to mentally travel through time. In animals, however, evidence of what-where-when memory (hereafter, WWW memory) is limited to very few taxa, mostly reflecting the socioecological challenges faced in their environment. In this article, we aimed to replicate 2 studies previously conducted on birds and primates to find convincing evidence of WWW memory in great apes. For this purpose, we tested 12 captive great apes in 3 different tasks. In Task 1, we tested whether great apes take into account temporal information when choosing between highly preferred perishable and less-preferred nonperishable food items. In Task 2, we tested whether great apes can differentiate between similar events having happened at different times in the past. Finally, in Task 3, we tested whether great apes can use their memory flexibly, incorporating novel information in their memories. In none of the tasks did our subjects make the correct choice significantly above chance, with performance further declining when subjects were presented with 2 events (Task 2). Moreover, none of them could reliably integrate novel information into their memories. Overall, our study casts doubt on the existence of WWW memory in great apes, and especially calls for more caution when using WWW memory tasks and interpreting their results. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

A functional connectome phenotyping dataset including cognitive state and personality measures.

The dataset enables exploration of higher-order cognitive faculties, self-generated mental experience, and personality features in relation to the intrinsic functional architecture of the brain. We provide multimodal magnetic resonance imaging (MRI) data and a broad set of state and trait phenotypic assessments: mind-wandering, personality traits, and cognitive abilities. Specifically, 194 healthy participants (between 20 and 75 years of age) filled out 31 questionnaires, performed 7 tasks, and reported 4 probes of in-scanner mind-wandering. The scanning session included four 15.5-min resting-state functional MRI runs using a multiband EPI sequence and a hig h-resolution structural scan using a 3D MP2RAGE sequence. This dataset constitutes one part of the MPI-Leipzig Mind-Brain-Body database.

Association of peripheral blood pressure with gray matter volume in 19- to 40-year-old adults.

OBJECTIVE: To test whether elevated blood pressure (BP) relates to gray matter (GM) volume (GMV) changes in young adults who had not previously been diagnosed with hypertension (systolic BP [SBP]/diastolic BP [DBP] ≥140/90 mm Hg). METHODS: We associated BP with GMV from structural 3T T1-weighted MRI of 423 healthy adults between 19 and 40 years of age (mean age 27.7 ± 5.3 years, 177 women, SBP/DBP 123.2/73.4 ± 12.2/8.5 mm Hg). Data originated from 4 previously unpublished cross-sectional studies conducted in Leipzig, Germany. We performed voxel-based morphometry on each study separately and combined results in image-based meta-analyses (IBMA) to assess cumulative effects across studies. Resting BP was assigned to 1 of 4 categories: (1) SBP <120 and DBP <80 mm Hg, (2) SBP 120-129 or DBP 80-84 mm Hg, (3) SBP 130-139 or DBP 85-89 mm Hg, (4) SBP ≥140 or DBP ≥90 mm Hg. RESULTS: IBMA yielded the following results: (1) lower regional GMV was correlated with higher peripheral BP; (2) lower GMV was found with higher BP when comparing individuals in subhypertensive categories 3 and 2, respectively, to those in category 1; (3) lower BP-related GMV was found in regions including hippocampus, amygdala, thalamus, frontal, and parietal structures (e.g., precuneus). CONCLUSION: BP ≥120/80 mm Hg was associated with lower GMV in regions that have previously been related to GM decline in older individuals with manifest hypertension. Our study shows that BP-associated GM alterations emerge continuously across the range of BP and earlier in adulthood than previously assumed. This suggests that treating hypertension or maintaining lower BP in early adulthood might be essential for preventing the pathophysiologic cascade of asymptomatic cerebrovascular disease to symptomatic end-organ damage, such as stroke or dementia.

Author Correction: Preschool children and chimpanzees incur costs to watch punishment of antisocial others.

In the version of this Article originally published, in Fig. 2c the hatching indicating antisocial behaviour was on the wrong data bars. This has now been corrected in the Article.

Preschool children and chimpanzees incur costs to watch punishment of antisocial others.

When misfortune befalls another, humans may feel distress, leading to a motivation to escape. When such misfortune is perceived as justified, however, it may be experienced as rewarding and lead to motivation to witness the misfortune. We explored when in human ontogeny such a motivation emerges and whether the motivation is shared by chimpanzees. Chimpanzees and four- to six-year-old children learned through direct interaction that an agent was either prosocial or antisocial and later saw each agent's punishment. They were given the option to invest physical effort (chimpanzees) or monetary units (children) to continue watching. Chimpanzees and six-year-olds showed a preference for watching punishment of the antisocial agent. An additional control experiment in chimpanzees suggests that these results cannot be attributed to more generic factors such as scene coherence or informational value seeking. This indicates that both six-year-olds and chimpanzees have a motivation to watch deserved punishment enacted.

A high resolution 7-Tesla resting-state fMRI test-retest dataset with cognitive and physiological measures.

Here we present a test-retest dataset of functional magnetic resonance imaging (fMRI) data acquired at rest. 22 participants were scanned during two sessions spaced one week apart. Each session includes two 1.5 mm isotropic whole-brain scans and one 0.75 mm isotropic scan of the prefrontal cortex, giving a total of six time-points. Additionally, the dataset includes measures of mood, sustained attention, blood pressure, respiration, pulse, and the content of self-generated thoughts (mind wandering). This data enables the investigation of sources of both intra- and inter-session variability not only limited to physiological changes, but also including alterations in cognitive and affective states, at high spatial resolution. The dataset is accompanied by a detailed experimental protocol and source code of all stimuli used.

Chimpanzees form long-term memories for food locations after limited exposure.

Remembering the location of fruiting trees for extended periods of time has been hypothesized to play a major role in the evolution of primate cognition. Such ability would be especially useful when paired with a fast learning mechanism capable of consolidating long-term memory after minimal exposure. We investigated whether chimpanzees (Pan troglodytes) can remember different food locations after minimal exposure (i.e., 1-2 trials) both after 24 hr and after 3-month. We released pairs of chimpanzees in their indoor enclosure (the enclosure of group A measured 430 m(2) and group B's measured 175 m(2) ) and tested them for four consecutive days (Baseline, Test, Retest, and Post-test). During the Test and Retest food was hidden in the same location whereas no food was hidden during the Baseline and Post-test days (control trials). Subjects were tested with four different locations and assessed for their retention after 24 hr and 3-month since the initial food discovery. Results revealed that chimpanzees accurately remembered the locations in which they found the food after one or two exposures to them, and both after 24 hr and a 3-month retention interval.

Comparing the performances of apes (Gorilla gorilla, Pan troglodytes, Pongo pygmaeus) and human children (Homo sapiens) in the floating peanut task.

Recently, Mendes et al. [1] described the use of a liquid tool (water) in captive orangutans. Here, we tested chimpanzees and gorillas for the first time with the same "floating peanut task." None of the subjects solved the task. In order to better understand the cognitive demands of the task, we further tested other populations of chimpanzees and orangutans with the variation of the peanut initially floating or not. Twenty percent of the chimpanzees but none of the orangutans were successful. Additional controls revealed that successful subjects added water only if it was necessary to obtain the nut. Another experiment was conducted to investigate the reason for the differences in performance between the unsuccessful (Experiment 1) and the successful (Experiment 2) chimpanzee populations. We found suggestive evidence for the view that functional fixedness might have impaired the chimpanzees' strategies in the first experiment. Finally, we tested how human children of different age classes perform in an analogous experimental setting. Within the oldest group (8 years), 58 percent of the children solved the problem, whereas in the youngest group (4 years), only 8 percent were able to find the solution.

Primates do not spontaneously use shape properties for object individuation: a competence or a performance problem?

Several recent studies have documented that non-human primates can individuate objects according to property and/or kind information in much the same way as human infants do from around one year of age when they begin to acquire language. Some studies suggest, however, that only some properties are used for the individuation of food items: color, but not shape. The present study investigated whether these findings reveal a true competence problem with shape properties in the food domain or whether they merely reveal a performance problem (e.g., lack of attention to shapes). We tested 25 great apes (chimpanzees, bonobos and gorillas) in two food individuation tasks. We manipulated subjects' experience with differences in color and shape properties of food items. Results indicated (i) that all subjects, regardless of their prior experience, solved the color-based object individuation task and (ii) that only the group with previous experience with different shape properties succeeded in the shape-based individuation task. Great apes can thus be primed to take shape into account for individuating food objects, and this results clearly speaks in favor of a performance (rather than a competence) problem in using shape for object individuation of food items.

Ape metaphysics: object individuation without language.

Developmental research suggests that whereas very young infants individuate objects purely on spatiotemporal grounds, from (at latest) around 1 year of age children are capable of individuating objects according to the kind they belong to and the properties they instantiate. As the latter ability has been found to correlate with language, some have speculated whether it might be essentially language dependent and therefore uniquely human. Existing studies with non-human primates seem to speak against this hypothesis, but fail to present conclusive evidence due to methodological shortcomings. In the present experiments we set out to test non-linguistic object individuation in three great ape species with a refined manual search methodology. Experiment 1 tested for spatiotemporal object individuation: Subjects saw 1 or 2 objects simultaneously being placed inside a box in which they could reach, and then in both conditions only found 1 object. After retrieval of the 1 object, subjects reached again significantly more often when they had seen 2 than when they had seen 1 object. Experiment 2 tested for object individuation according to property/kind information only: Subjects saw 1 object being placed inside the box, and then either found that object (expected) or an object of a different kind (unexpected). Analogously to Experiment 1, after retrieval of the 1 object, subjects reached again significantly more often in the unexpected than in the expected condition. These results thus confirm previous findings suggesting that individuating objects according to their property/kind is neither uniquely human nor essentially language dependent. It remains to be seen, however, whether this kind of object individuation requires sortal concepts as human linguistic thinkers use them, or whether some simpler form of tracking properties is sufficient.

Raising the level: orangutans use water as a tool.

We investigated the use of water as a tool by presenting five orangutans (Pongo abelii) with an out-of-reach peanut floating inside a vertical transparent tube. All orangutans collected water from a drinker and spat it inside the tube to get access to the peanut. Subjects required an average of three mouthfuls of water to get the peanut. This solution occurred in the first trial and all subjects continued using this successful strategy in subsequent trials. The latency to retrieve the reward drastically decreased after the first trial. Moreover, the latency between mouthfuls also decreased dramatically from the first mouthful in the first trial to any subsequent ones in the same trial or subsequent trials. Additional control conditions suggested that this response was not due to the mere presence of the tube, to the existence of water inside, or frustration at not getting the reward. The sudden acquisition of the behaviour, the timing of the actions and the differences with the control conditions make this behaviour a likely candidate for insightful problem solving.

Object permanence in common marmosets (Callithrix jacchus).

A series of 9 search tasks corresponding to the Piagetian Stages 3-6 of object permanence were administered to 11 common marmosets (Callithrix jacchus). Success rates varied strongly among tasks and marmosets, but the performances of most subjects were above chance level on the majority of tasks of visible and invisible displacements. Although up to 24 trials were administered in the tests, subjects did not improve their performance across trials. Errors were due to preferences for specific locations or boxes, simple search strategies, and attentional deficits. The performances of at least 2 subjects that achieved very high scores up to the successive invisible displacement task suggest that this species is able to represent the existence and the movements of unperceived objects.