Gaze Duration Biases for Colours in Combination with Dissonant and Consonant Sounds: A Comparative Eye-Tracking Study with Orangutans

Color Biases and Preferences in Zoo-Housed Chimpanzees (Pan troglodytes), Gorillas (Gorilla gorilla gorilla), and Japanese Macaques (Macaca fuscata)

Colors are an important signal for many primate species and have the potential to influence behavior and cognition. Primates may consciously or unconsciously prioritize their attention toward certain color stimuli to quickly identify consequential events, conspecifics, or resources. On the other hand, primates' color preferences can be modulated by memory, experiences, and affective responses. Few studies have explored the multifaceted nature of attention to colors in primate species that vary in their socioecologies and phenotypes, both of which may influence their responses to specific colors. The colors that rapidly capture primates' attention, and those they prefer, thus remain poorly understood. In a series of touchscreen experiments, we investigated responses to 9 perceptually distinct colored squares by 7 chimpanzees (Pan troglodytes), 11 gorillas (Gorilla gorilla gorilla), and 10 Japanese macaques (Macaca fuscata). We controlled for contextual cues known to influence color responses and assessed attentional biases using a dot probe task (Experiment 1) and preferences using a two-item forced-choice task (Experiments 2 and 3). In Experiment 1, we found that chimpanzees and gorillas showed the strongest attentional bias toward black, whereas the Japanese macaques showed the strongest bias toward red. These attentional biases suggest a potential relationship between species coloration and their attention to colors. In Experiments 2 and 3, all three species preferentially selected red, with Japanese macaques showing the strongest preference, supporting earlier findings that highlighted red as a particularly salient color to primates. Future research is needed to investigate the role of prior experience on primates' responses to colors.

Experiencing beauty in everyday life

Beauty surrounds us in many ways every day. In three experience sampling (ESM) studies we investigated frequency, category of eliciting stimuli (natural vs human-made) and, the potential moderating role of several individual difference measures on such everyday experiences of beauty in an ecologically valid manner. Further, we explored the impact of such experiences on valence & arousal. Study 1 re-analysed data from a previous study, in line with the current aims. In Studies 2 and 3, we asked participants to report daily experiences of beauty using a mixed random and event-contingent sampling schedule. Mobile notifications (random sampling) prompted participants to take a photo and rate the beauty of their surroundings. Further, current valence and arousal were assessed. Notification frequency and total days of participation differed between these two studies. Participants were able to report additional experiences outside of the notification windows (event-contingent sampling). Our results indicate that we frequently encounter beauty in everyday life and that we find it in nature, in particular. Our results further suggest a mood-boosting effect of encounters with beauty. Lastly, our results indicate influences of individual differences however, these were inconclusive and require further attention.

Differences in regional gray matter volume predict the extent to which openness influences judgments of beauty and pleasantness of interior architectural spaces

Hedonic evaluation of sensory objects varies from person to person. While this variability has been linked to differences in experience, little is known about why stimuli lead to different evaluations in different people. We used linear mixed-effects models to determine the extent to which the openness, contour, and ceiling height of interior spaces influenced the beauty and pleasantness ratings of 18 participants. Then, by analyzing structural brain images acquired for the same group of participants, we asked if any regional gray matter volume (rGMV) covaried with these differences in the extent to which the three features influence beauty and pleasantness ratings. Voxel-based morphometry analysis revealed that the influence of openness on pleasantness ratings correlated with rGMV in the anterior prefrontal cortex (Brodmann area (BA)-10), and the influence of openness on beauty ratings correlated with rGMV in the temporal pole (BA38) and cluster, including the posterior cingulate cortex (BA31) and paracentral lobule (BA5/6). There were no significant correlations involving contour or ceiling height. Our results suggest that regional variance in gray matter volume may play a role in the computation of hedonic valuation and account for differences in the way people weigh certain attributes of interior architectural spaces.

The application of noninvasive, restraint-free eye-tracking methods for use with nonhuman primates

Over the past 50 years there has been a strong interest in applying eye-tracking techniques to study a myriad of questions related to human and nonhuman primate psychological processes. Eye movements and fixations can provide qualitative and quantitative insights into cognitive processes of nonverbal populations such as nonhuman primates, clarifying the evolutionary, physiological, and representational underpinnings of human cognition. While early attempts at nonhuman primate eye tracking were relatively crude, later, more sophisticated and sensitive techniques required invasive protocols and the use of restraint. In the past decade, technology has advanced to a point where noninvasive eye-tracking techniques, developed for use with human participants, can be applied for use with nonhuman primates in a restraint-free manner. Here we review the corpus of recent studies (N=32) that take such an approach. Despite the growing interest in eye-tracking research, there is still little consensus on "best practices," both in terms of deploying test protocols or reporting methods and results. Therefore, we look to advances made in the field of developmental psychology, as well as our own collective experiences using eye trackers with nonhuman primates, to highlight key elements that researchers should consider when designing noninvasive restraint-free eye-tracking research protocols for use with nonhuman primates. Beyond promoting best practices for research protocols, we also outline an ideal approach for reporting such research and highlight future directions for the field.

A new conception of visual aesthetic sensitivity

Aesthetic sensitivity has been defined as the ability to recognize and appreciate beauty and compositional excellence, and to judge artistic merit according to standards of aesthetic value. The Visual Aesthetic Sensitivity Test (VAST) has often been used to assess this ability, but recent research has revealed it has several psychometric problems. Such problems are not easily remedied, because they reflect flawed assumptions inherent to the concept of aesthetic sensitivity as traditionally understood, and to the VAST itself. We introduce a new conception of aesthetic sensitivity defined as the extent to which someone's aesthetic valuation is influenced by a given feature. Experiment 1 aimed to characterize aesthetic sensitivity to four prominent features in visual aesthetics: complexity, symmetry, contour, and balance. Experiment 2 aimed to replicate the findings of Experiment 1 and to assess the test-retest reliability of an instrument designed to measure aesthetic sensitivity to these features using an abridged set of stimuli. Our results reveal that people differ remarkably in the extent to which visual features influence their liking, highlighting the crucial role of individual variation when modelling aesthetic preferences. We did not find clear relations between the four measures of aesthetic sensitivity and personality, intelligence, and art interest and knowledge. Finally, our measurement instrument exhibited an adequate-to-good test-retest reliability.

Stability and Variability in Aesthetic Experience: A Review

Based on psychophysics’ pragmatic dualism, we trace the cognitive neuroscience of stability and variability in aesthetic experience. With regard to different domains of aesthetic processing, we touch upon the relevance of cognitive schemata for aesthetic preference. Attitudes and preferences are explored in detail. Evolutionary constraints on attitude formation or schema generation are elucidated, just as the often seemingly arbitrary influences of social, societal, and cultural nature are. A particular focus is put on the concept of critical periods during an individual’s ontogenesis. The latter contrasting with changes of high frequency, such as fashion influences. Taken together, these analyses document the state of the art in the field and, potentially, highlight avenues for future research.

Cultural and Species Differences in Gazing Patterns for Marked and Decorated Objects: A Comparative Eye-Tracking Study

Objects from the Middle Paleolithic period colored with ochre and marked with incisions represent the beginning of non-utilitarian object manipulation in different species of the Homo genus. To investigate the visual effects caused by these markings, we compared humans who have different cultural backgrounds (Namibian hunter–gatherers and German city dwellers) to one species of non-human great apes (orangutans) with respect to their perceptions of markings on objects. We used eye-tracking to analyze their fixation patterns and the durations of their fixations on marked and unmarked stones and sticks. In an additional test, humans evaluated the objects regarding their aesthetic preferences. Our hypotheses were that colorful markings help an individual to structure the surrounding world by making certain features of the environment salient, and that aesthetic appreciation should be associated with this structuring. Our results showed that humans fixated on the marked objects longer and used them in the structural processing of the objects and their background, but did not consistently report finding them more beautiful. Orangutans, in contrast, did not distinguish between object and background in their visual processing and did not clearly fixate longer on the markings. Our results suggest that marking behavior is characteristic for humans and evolved as an attention-directing rather than aesthetic benefit.

Differences in the Visual Perception of Symmetric Patterns in Orangutans (Pongo pygmaeus abelii) and Two Human Cultural Groups: A Comparative Eye-Tracking Study

Symmetric structures are of importance in relation to aesthetic preference. To investigate whether the preference for symmetric patterns is unique to humans, independent of their cultural background, we compared two human populations with distinct cultural backgrounds (Namibian hunter-gatherers and German town dwellers) with one species of non-human great apes (Orangutans) in their viewing behavior regarding symmetric and asymmetric patterns in two levels of complexity. In addition, the human participants were asked to give their aesthetic evaluation of a subset of the presented patterns. The results showed that humans of both cultural groups fixated on symmetric patterns for a longer period of time, regardless of the pattern’s complexity. On the contrary, Orangutans did not clearly differentiate between symmetric and asymmetric patterns, but were much faster in processing the presented stimuli and scanned the complete screen, while both human groups rested on the symmetric pattern after a short scanning time. The aesthetic evaluation test revealed that the fixation preference for symmetric patterns did not match with the aesthetic evaluation in the Hai//om group, whereas in the German group aesthetic evaluation was in accordance with the fixation preference in 60 percent of the cases. It can be concluded that humans prefer well-ordered structures in visual processing tasks, most likely because of a positive processing bias for symmetry, which Orangutans did not show in this task, and that, in humans, an aesthetic preference does not necessarily accompany the fixation preference.