Are monkeys aesthetists? Rensch (1957) revisited

Preference test of sound among multiple alternatives in rats

Conditioned place preference (CPP) tests in rodents have been well established to measure preference induced by secondary reinforcing properties, but conventional assays are not sensitive enough to measure innate, weak preference, or the primary reinforcing property of a conditioned stimulus. We designed a novel CPP assay with better sensitivity and efficiency in quantifying and ranking preference of particular sounds among multiple alternatives. Each test tone was presented according to the location of free-moving rats in the arena, where assignment of location to each tone changed in every 20-s session. We demonstrated that our assay was able to rank tone preference among 4 alternatives within 12.5 min (125 s (habituation) + 25 s/sessions × 25 sessions). In order to measure and rank sound preference, we attempted to use sojourn times with each test sound ([Formula: see text]), and a preference index (PI) based on transition matrices of initial and end sounds in every session. Both [Formula: see text] and PI revealed similar trends of innate preference in which rats preferred test conditions in the following order: silence, 40-, 20-, then 10-kHz tones. Further, rats exhibited a change in preference after an classical conditioning of the 20-kHz tone with a rewarding microstimulation of the dopaminergic system. We also demonstrated that PI was a more robust and sensitive indicator than [Formula: see text] when the locomotion activity level of rats became low due to habituation to the assay repeated over sessions. Thus, our assay offers a novel method of evaluating auditory preference that is superior to conventional CPP assays, offering promising prospects in the field of sensory neuroscience.

Cross-cultural empirical aesthetics

Cross-cultural empirical aesthetics seeks to determine whether the psychological processes underlying aesthetic preference are universal. Here we provide a critical review of the field's origin, development, and current state. Our goal is to evaluate the evidence and separate what is actually known from what is only assumed. We conclude that the evidence shows that people from different cultures base their aesthetic preference on a common set of formal features, including symmetry, complexity, proportion, contour, brightness, and contrast. The reason for this commonality is that aesthetic preference emerges from basic perceptual and valuation processes that are common to all humans, and to many other animals.

Physical Features of Visual Images Affect Macaque Monkey's Preference for These Images

Animals exhibit different degrees of preference toward various visual stimuli. In addition, it has been shown that strongly preferred stimuli can often act as a reward. The aim of the present study was to determine what features determine the strength of the preference for visual stimuli in order to examine neural mechanisms of preference judgment. We used 50 color photographs obtained from the Flickr Material Database (FMD) as original stimuli. Four macaque monkeys performed a simple choice task, in which two stimuli selected randomly from among the 50 stimuli were simultaneously presented on a monitor and monkeys were required to choose either stimulus by eye movements. We considered that the monkeys preferred the chosen stimulus if it continued to look at the stimulus for an additional 6 s and calculated a choice ratio for each stimulus. Each monkey exhibited a different choice ratio for each of the original 50 stimuli. They tended to select clear, colorful and in-focus stimuli. Complexity and clarity were stronger determinants of preference than colorfulness. Images that included greater amounts of spatial frequency components were selected more frequently. These results indicate that particular physical features of the stimulus can affect the strength of a monkey’s preference and that the complexity, clarity and colorfulness of the stimulus are important determinants of this preference. Neurophysiological studies would be needed to examine whether these features of visual stimuli produce more activation in neurons that participate in this preference judgment.

Common Visual Preference for Curved Contours in Humans and Great Apes

Among the visual preferences that guide many everyday activities and decisions, from consumer choices to social judgment, preference for curved over sharp-angled contours is commonly thought to have played an adaptive role throughout human evolution, favoring the avoidance of potentially harmful objects. However, because nonhuman primates also exhibit preferences for certain visual qualities, it is conceivable that humans’ preference for curved contours is grounded on perceptual and cognitive mechanisms shared with extant nonhuman primate species. Here we aimed to determine whether nonhuman great apes and humans share a visual preference for curved over sharp-angled contours using a 2-alternative forced choice experimental paradigm under comparable conditions. Our results revealed that the human group and the great ape group indeed share a common preference for curved over sharp-angled contours, but that they differ in the manner and magnitude with which this preference is expressed behaviorally. These results suggest that humans’ visual preference for curved objects evolved from earlier primate species’ visual preferences, and that during this process it became stronger, but also more susceptible to the influence of higher cognitive processes and preference for other visual features.

The biological roots of aesthetics and art

Animals' choice behavior is driven by motivation that is attributable to both innate urges and from positive and negative reinforcements. Using a comparative approach as well as experimental evidence, I explore how the first involves fitness-enhancing benefits from aesthetics that are derived from ancestral choices via natural selection. Innate urges and aesthetics help guide animals to produce appropriate positive and negative choices that are species-specific. Choices of food, habitat and mates or associates are considered. I propose that art is not a uniquely human product, but a representation or an extension of the maker, as are the ornaments, displays, and songs of a bird.

Bowerbirds, art and aesthetics: Are bowerbirds artists and do they have an aesthetic sense?

Male bowerbirds create and decorate a structure called a bower which serves only to attract females for mating, and females visit and choose one among many bower owners before deciding which male to mate with. Is what they do art, and do they have an aesthetic sense? I propose operational definitions of art, judgement, and an aesthetic sense which depend upon communication theory which allow one to get explicit answers to this question. By these definitions Great Bowerbirds are artists, judge art, and therefore have an aesthetic sense.

Discrimination of painting style and quality: pigeons use different strategies for different tasks

Birds have visual cognition as well developed as humans. Sometimes, the birds show visual discrimination similar to humans, but the birds may use different cues. Previous reports suggest that global configuration cues are salient for humans, whereas local elemental cues are salient for pigeons. I analyzed the discriminative behavior of pigeons with scrambled images because scrambled images keep the local elemental cues of the original images but lose the global configuration cues. If pigeons use local elemental cues, then, they should show transfer of discrimination from the original images to their scrambled images and also transfer from the scrambled images to their original images. In Experiment I, I trained pigeons on painting style discrimination (Japanese paintings vs. Western impressionist paintings) using either the original or scrambled images and found that the pigeons showed bidirectional transfer. In Experiment II, I trained pigeons on discrimination of "good" versus "bad" paintings using children's paintings. The birds showed poor transfer from the original images to their scrambled images and vise versa. Thus, the pigeons discriminated good and bad paintings based mostly on global configuration cues in this case. These results suggest that the pigeons use different cues for different discriminations.

Colour versus quantity as cues in reverse-reward-competent squirrel monkeys (Saimiri sciureus)

To assess the relative salience of colour and quantity cues, squirrel monkeys previously trained to reach for the smaller of two quantities of food in a reverse-reward contingency task received colour discrimination training. After initial failure to discriminate between two colours of dots under a differential reinforcement regime, they learned the task when the S− colour was associated with zero reward. The monkeys then showed good retention on the original reverse-reward task of 1 versus 4 with pairs of dots presented in S+ or S− colours. However, on “mismatch” trials of 1S− versus 4S+, only 2 of 4 monkeys tested showed a preference—1 monkey chose based on quantity, the other based on colour. Individual differences and the possible roles of overshadowing and blocking are discussed.

Symmetrical crypsis and asymmetrical signalling in the cuttlefish Sepia officinalis

The salience of bilateral symmetry to humans has led to the suggestion that camouflage may be enhanced in asymmetrical patterns. However, the importance of bilateral symmetry in visual signals (and overall morphology) may constrain the evolution of asymmetrical camouflage, resulting in the bilaterally symmetrical cryptic patterns that we see throughout the animal kingdom. This study investigates the cuttlefish (Sepia officinalis), which can control the degree of symmetry in its coloration. Ten juvenile S. officinalis were filmed in two behavioural contexts (cryptic and threatened) to test the prediction that cryptic patterns will be expressed more asymmetrically than an anti-predator signal known as the 'deimatic display'. Cryptic body patterns, particularly those with a disruptive function, were found to exhibit a high degree of bilateral symmetry. By contrast, the components of the deimatic display were often expressed asymmetrically. These results are contrary to the predicted use of symmetry in defensive coloration, indicating that the role of symmetry in both crypsis and visual signalling is not as straightforward as previously suggested.

Mechanisms of same/different concept learning in primates and avians

Mechanisms of same/different concept learning by rhesus monkeys, capuchin monkeys, and pigeons were studied in terms of how these species learned the task (e.g., item-specific learning versus relational learning) and how rapidly they learned the abstract concept, as the training set size was doubled. They had similar displays, training stimuli, test stimuli, and contingencies. The monkey species learned the abstract concept at similar rates and more rapidly than pigeons, thus showing a quantitative difference across species. All species eventually showed full concept learning (novel-stimulus transfer equivalent to baseline: 128-item set size for monkeys; 256-item set for pigeons), thus showing a qualitative similarity across species. Issues of stimulus regularity/symmetry, generalization from item pairs, and familiarity processing were not considered to be major factors in the final performances, converging on the conclusion that these species were increasingly controlled by the sample-test relationship (i.e., relational processing) leading to full abstract-concept learning.