Unfamiliar faces might as well be another species: Evidence from a face matching task with human and monkey faces

Humans are good at recognizing familiar faces, but are more error-prone at recognizing an unfamiliar person across different images. It has been suggested that familiar and unfamiliar faces are processed qualitatively differently. But are unfamiliar faces at least processed differently from monkey faces? Here we tested 366 volunteers on a face matching test – two images presented side-by-side with participants judging whether the images show the same identity or two different identities – comparing performance with familiar and unfamiliar human faces, and monkey faces. The results showed that performance was most accurate for familiar faces, and was above chance for monkey faces. Although accuracy was higher for unfamiliar humans than monkeys on different identity trials, there was no unfamiliar human advantage over monkeys on same identity trials. The results give new insights into unfamiliar face processing, showing that in some ways unfamiliar faces might as well be another species

Cooperation and group similarity in children and young adults in the UK

For cooperation to be beneficial, cooperators should be able to differentiate individuals who are willing to cooperate from free-riders. In the absence of kin or of familiar individuals, phenotypic similarity (e.g. in terms of language) can be used as a cue of how likely two or more individuals would behave similarly (cooperate or free-ride). Thus, phenotypic similarity could affect cooperation. However, it is unclear whether humans respond to any type of phenotypic similarity or whether only salient phenotypic traits guide cooperation. We tested whether within-group, non-salient phenotypic similarity affects cooperation in 280, 3-10 year old children and in 76 young adults (mean: 19.8 years old) in the UK. We experimentally manipulated the degree of phenotypic similarity in three computer-based experiments. We found no evidence of a preference for, or greater cooperation with, phenotypically similar individuals in children, even though children displayed ingroup preference. Conversely, young adults cooperated more with phenotypically similar than with phenotypically diverse individuals as themselves. Our results suggest that response to non-salient phenotypic similarity varies with age and that young adults may pay more attention to non-salient cues of diversity then children

The IUCN Best Practice Guidelines one year on: Addressing some misunderstandings and encouraging primatologists to be responsible messengers

As primatologists we take photographs and videos of our study animals, both in the wild and in captivity (zoos and rescue/rehabilitation centres). We use these images across social media (personal and public accounts), on websites, and give them to TV and film crews. We use these images to promote our work and share our findings with colleagues and the general public. We also participate in films where we are often close to primates and some of us work in countries where primates are routinely kept and traded as pets. In January 2021, after extensive feedback and review from all IUCN SSC Primate Specialist Group members, we as members of the IUCN Primate Specialist Group Section for Human-Primate Interactions published the Best Practice Guidelines for Responsible Images of Non-Human Primates online https://human-primate-interactions.org/resources/. Here, we remind readers of the purpose of the guidelines, and reiterate our call to primatologists to play a key role in delivering suitable messages about primates

Distributed under Creative Commons CC-BY 4.0 Experience-based human perception of facial expressions in Barbary macaques (Macaca sylvanus)

ABSTRACT Background. Facial expressions convey key cues of human emotions, and may also be important for interspecies interactions. The universality hypothesis suggests that six basic emotions (anger, disgust, fear, happiness, sadness, and surprise) should be expressed by similar facial expressions in close phylogenetic species such as humans and nonhuman primates. However, some facial expressions have been shown to differ in meaning between humans and nonhuman primates like macaques. This ambiguity in signalling emotion can lead to an increased risk of aggression and injuries for both humans and animals. This raises serious concerns for activities such as wildlife tourism where humans closely interact with wild animals. Understanding what factors (i.e., experience and type of emotion) affect ability to recognise emotional state of nonhuman primates, based on their facial expressions, can enable us to test the validity of the universality hypothesis, as well as reduce the risk of aggression and potential injuries in wildlife tourism. Methods. The present study investigated whether different levels of experience of Barbary macaques, Macaca sylvanus, affect the ability to correctly assess different facial expressions related to aggressive, distressed, friendly or neutral states, using an online questionnaire. Participants' level of experience was defined as either: (1) naïve: never worked with nonhuman primates and never or rarely encountered live Barbary macaques; (2) exposed: shown pictures of the different Barbary macaques' facial expressions along with the description and the corresponding emotion prior to undertaking the questionnaire; (3) expert: worked with Barbary macaques for at least two months. Results. Experience with Barbary macaques was associated with better performance in judging their emotional state. Simple exposure to pictures of macaques' facial expressions improved the ability of inexperienced participants to better discriminate neutral and distressed faces, and a trend was found for aggressive faces. However, these participants, even when previously exposed to pictures, had difficulties in recognising aggressive, distressed and friendly faces above chance level. Discussion. These results do not support the universality hypothesis as exposed and naïve participants had difficulties in correctly identifying aggressive, distressed and friendly faces. Exposure to facial expressions improved their correct recognition. In addition, the findings suggest that providing simple exposure to 2D pictures (for example, information signs explaining animals' facial signalling in zoos or animal parks) is not a sufficient educational tool to reduce tourists' misinterpretations of macaque emotion. Additional measures, such as keeping a safe distance between tourists and wild animals, as well as reinforcing learning via videos or supervised visits led b

Scatterplot showing scores for PCA 1 (body size) and PCA 2 (body shape) for each individual from TG and GG.

<p>Each point represents an individual, categorised by group and sex.</p

Graph of the intensity of provisioning (%) from March to December 2012.

<p>Intensity of provisioning represents the percentage of their feeding activity during which macaques were observed eating food provided by humans.</p

Scatterplots showing the comparison between TG and GG for: A) Female average body size, B) Male average alopecia scores, C) Female average FGC levels, D) Male average FGC levels.

<p>Symbols represent each individual and lines median values.</p

Examples of photogrammetry measurements for each body dimension measured.

<p>a) back sitting posture, b) front sitting posture, c) side standing posture.</p

Summary of the predictor variables and their definitions.

<p>Summary of the predictor variables and their definitions.</p