Visual Communication Signals Research Articles

Look into my eyes: a “faceless” avatar interviewer lowers reporting threshold for adult eyewitnesses

Evidential interviewing is often used to gather important information, which can determine the outcome of a criminal case. An interviewer’s facial features, however, may impact reporting during this task. Here, we investigated adults’ interview performance using a novel tool—a faceless avatar interviewer—designed to minimize the impact of an interviewer’s visual communication signals, potentially enhancing memory performance. Adults were interviewed about the details of a video by (1) a human-appearing avatar or a human interviewer (Experiment 1; N = 105) or (2) a human-appearing avatar or a faceless avatar interviewer (Experiment 2; N = 109). Participants assigned to the avatar interviewer condition were (1) asked whether they thought the interviewer was either computer or human operated (Experiment 1) or (2) explicitly told that the interviewer was either computer or human operated (Experiment 2). Adults’ memory performance was statistically equivalent when they were interviewed by a human-appearing avatar or a human interviewer, but, relative to the human-appearing avatar, adults who were interviewed by a faceless avatar reported more correct (but also incorrect) details in response to free-recall questions. Participants who indicated that the avatar interviewer was computer operated—as opposed to human operated—provided more accurate memory reports, but specifically telling participants that the avatar was computer operated or human operated had no influence on their memory reports. The present study introduced a novel interviewing tool and highlighted the possible cognitive and social influences of an interviewer’s facial features on adults’ report of a witnessed event.

The image features of emotional faces that predict the initial eye movement to a face

Emotional facial expressions are important visual communication signals that indicate a sender’s intent and emotional state to an observer. As such, it is not surprising that reactions to different expressions are thought to be automatic and independent of awareness. What is surprising, is that studies show inconsistent results concerning such automatic reactions, particularly when using different face stimuli. We argue that automatic reactions to facial expressions can be better explained, and better understood, in terms of quantitative descriptions of their low-level image features rather than in terms of the emotional content (e.g. angry) of the expressions. Here, we focused on overall spatial frequency (SF) and localized Histograms of Oriented Gradients (HOG) features. We used machine learning classification to reveal the SF and HOG features that are sufficient for classification of the initial eye movement towards one out of two simultaneously presented faces. Interestingly, the identified features serve as better predictors than the emotional content of the expressions. We therefore propose that our modelling approach can further specify which visual features drive these and other behavioural effects related to emotional expressions, which can help solve the inconsistencies found in this line of research.

Object colours, material properties and animal signals.

Humans and other animals often use colour to recognise objects regardless of their context - as a measure of material properties rather than of their contrast with a background. Most work on visual communication signals is, however, concerned with colour differences, typically scaled by just noticeable differences (JNDs). Here, we move from the prevailing physiological framework to understand what a given colour or type of colour might tell an animal about an object. To this end, we consider the properties of object colour solids, which represent the colour gamut of reflective materials for a given type of animal eye. The geometry of colour solids reveals general relationships between colours and object properties, which can explain why certain colours are significant to animals, and hence evolve as signals. We define a measure of colour vividness, such that points on the surface are maximally vivid and the 'grey' centre is minimally vivid. We show that a vivid colour for one animal is likely to be vivid for others, and highly vivid colours are less easily mimicked than less vivid colours. Furthermore, vivid colours such as black, white, red and blue, as well as pale colours and certain unsaturated shades, are produced by pure or orderly materials. Such materials are created and maintained against entropic processes. Vivid colours are therefore indicative of ecological affordance or biological function, so it is valuable to have low-level psychological biases towards these colours regardless of any specific significance they might have to the receiver.

The Tyranny of the Empty Frame

This study explores the notion of the “tyranny of the empty frame” within the online departments of the two leading Slovenian newspapers, Delo and Dnevnik, where online journalists—newsworkers with little or no training or experience in photojournalism—are required to provide each news item with at least one photograph. By adopting newsroom observation and in-depth interviews with online journalists working for Delo and Dnevnik, we investigate paradoxes associated with this imperative. Despite often being faced with a desperate search for “any image,” online journalists at both institutions are reluctant to use citizen-produced photographs—their use appears to be an aberration rather than a norm. Instead, they frequently resort to using what they refer to as a “symbolic photograph” to overcome the lack of visual material originating from the reported event. This move from indexical–iconic nexus to metaphoric visual communication signals challenges to the dominant paradigm of press photography. At the same time, we suggest that we should not view the phenomena of citizen photojournalism as a radical break with the past but as the latest development in a series of interrelated processes, intellectual projects of modernity, such as ocularcentrism, journalism, capitalism and the nation state.

Rhesus Macaques Recognize Unique Multimodal Face-Voice Relations of Familiar Individuals and Not of Unfamiliar Ones

Communication signals in nonhuman primates are inherently multimodal. However, for laboratory-housed monkeys, there is relatively little evidence in support of the use of multimodal communication signals in individual recognition. Here, we used a preferential-looking paradigm to test whether laboratory-housed rhesus monkeys could ‘spontaneously' (i.e., in the absence of operant training) use multimodal communication stimuli to discriminate between known conspecifics. The multimodal stimulus was a silent movie of 2 monkeys vocalizing and an audio file of the vocalization from one of the monkeys in the movie. We found that the gaze patterns of the monkeys that knew the individuals in the movie were reliably biased toward the individual that did not produce the vocalization. In contrast, there was not a systematic gaze pattern for the monkeys that did not know the individuals in the movie. These data are consistent with the hypothesis that laboratory-housed rhesus macaques can recognize and distinguish between conspecifics based on auditory and visual communication signals.

Exposure to an environmental estrogen breaks down sexual isolation between native and invasive species.

Environmental change can increase the likelihood of interspecific hybridization by altering properties of mate recognition and discrimination between sympatric congeners. We examined how exposure to an environmentally widespread endocrine-disrupting chemical (EDC), bisphenol A (BPA), affected visual communication signals and behavioral isolation between an introduced freshwater fish and a native congener (genus: Cyprinella). Exposure to BPA induced changes in the expression of male secondary traits as well as male and female mate choice, leading to an overall reduction in prezygotic isolation between congeners. Changes in female mate discrimination were not tightly linked to changes in male phenotypic traits, suggesting that EDC exposure may alter female choice thresholds independently of the effects of exposure on males. These findings indicate that environmental exposure to EDCs can lead to population declines via the erosion of species boundaries and by promoting the establishment and spread of non-native species via hybridization.

Behavioral Isolation Based on Visual Signals in a Sympatric Pair of Darter Species

AbstractElaborate visual communication signals characterize many animal lineages. Often sex‐limited, these signals are generally assumed to result from sexual selection, and in many cases, their evolution is thought to play a central role in speciation. The co‐evolution of male visual signals and female preferences is hypothesized to result in behavioral isolation between divergent lineages; however, for many lineages characterized by elaborate visual signals, the importance of visual differences in behavioral isolation is not well established. Darters (fish genus Etheostoma) are particularly appropriate for examining the role of visual signals in behavioral isolation. They comprise one of the most diverse groups of North American freshwater fish, and nearly every species is characterized by unique nuptial coloration. Multiple darter species co‐exist in sympatric populations, indicating that reproductive barriers are central to maintaining these extraordinarily diverse color patterns. This study demonstrates the presence of behavioral isolation between a pair of distinctly colored sympatric darter species, Etheostoma barrenense and Etheostoma zonale, through experimental observations using an artificial stream. In addition, a series of dichotomous mate‐choice trials indicate that females prefer conspecific males over heterospecifics based on visual differences alone. We therefore provide the first evidence that visual signals are a critical trait maintaining behavioral isolation in darters, a lineage of fishes with spectacular diversification in visual communication.

A review of the evolution of animal colour vision and visual communication signals

The visual displays of animals and plants are often colourful, and colour vision allows animals to respond to these signals as they forage for food, choose mates and so-forth. This article discusses the evolutionary relationship between photoreceptor spectral sensitivities of four groups of land animals—birds, butterflies, primates and hymenopteran insects (bees and wasps)—, the colour signals that are relevant to them, and how understanding is informed by models of spectral coding and colour vision. Although the spectral sensitivities of photoreceptors are known to vary adaptively under natural selection there is little evidence that those of hymenopterans, birds and primates are specifically adapted to the reflectance spectra of food plants or animal visual signals. On the other hand, the colours of fruit, flowers and feathers may have evolved to be more discriminable for the colour vision of their natural receivers than for other groups of animals. Butterflies are unusual in that they have enjoyed a major radiation in receptor numbers and spectral sensitivities. The reasons for the radiation and diversity of butterfly colour vision remain unknown, but may include their need to find food plants and to select mates.

Differential use of attentional and visual communicative signaling by orangutans (Pongo pygmaeus) and gorillas (Gorilla gorilla) in response to the attentional status of a human

In this study we investigated the communicative abilities of 10 orangutans (Pongo pygmaeus) and seven western lowland gorillas (Gorilla gorilla gorilla), and particularly focused on their sensitivity to the attentional state of a human experimenter when choosing from a repertoire of both auditory and visual communication strategies. In experiment 1 a banana was placed in front of the subject's cage and a human experimenter was either present or absent. The subject's behavior was recorded for 60 sec. Both gorillas and orangutans gestured (t(16)=-3.58, P<.005) and vocalized (t(16)=-2.47, P<.05) more when the experimenter was present. In experiment 2 a human experimenter held a banana in front of the subject's cage and was oriented either toward or away from the subject. Again the subject's behavior was recorded for 60 sec. In this experiment both gorillas and orangutans gestured significantly more frequently (t(16)=3.40, P<.005) when the experimenter was oriented toward them. In addition, gorillas and orangutans used other forms of visual communication signals, such as lip pout (t(16)=3.66, P<.005), barter/trade (t(16)=2.31, P<.05), and body present (t(16)=2.31, P<.05) significantly more when an experimenter was facing them. The overall results indicate that both gorillas and orangutans are sensitive to the attentional state of a human experimenter and use appropriate communicative signals to gain that individual's attention. These results are also similar to previous findings on communicative behaviors in chimpanzees.

Detecting natural changes of cone-excitation ratios in simple and complex coloured images.

Ratios of excitations in each cone-photoreceptor class produced by light reflected from pairs of surfaces in a scene are almost invariant under natural illuminant changes. The stability of these spatially defined ratios may explain the remarkable ability of human observers to efficiently discriminate illuminant changes from changes in surface reflectances. Spatial cone-excitation ratios are not, however, exactly invariant. This study is concerned with observers' sensitivity to these invariance violations. Simulations of Mondrian paintings with either 49 or two natural surfaces under Planckian illuminants were presented as images on a computer-controlled display in a two-interval experimental design: in one interval, the surfaces underwent an illuminant change; in the other interval, the surfaces underwent the same change but the images were then corrected so that, for each cone class, ratios of excitations were preserved exactly. Although the intervals with corrected images corresponded individually to highly improbable natural events, observers systematically misidentified them as containing the illuminant changes, the probability of error increasing as the violation of invariance in the other interval increased. For the range of illuminants and surfaces tested, sensitivity to violations of invariance was found to depend on cone class: it was greatest for long-wavelength-sensitive cones and least for short-wavelength-sensitive cones. Spatial cone-excitation ratios, or some closely related quantities, seem to be the cues preferred by observers for making inferences about surface illuminant changes.

The Ontogeny of Display Behaviour in Sceloporus undulatus: (Sauria: Iguanidae)

AbstractA longitudinal study (from neonate to adult) was made of the display behaviour of 36 fence lizards from 8 clutches. A frame‐by‐frame analysis of 941 video‐taped displays revealed that the hatchlings possessed almost all of their adult display patterns by the first two days of life. Of the total variance in the display behaviour, 7% or less was attributed to experience. Of the variance among lizards, approximately half came from between clutches and half from between clutchmates. Our data indicate that the visual communication signals (head bob displays) of this vertebrate species are almost totally innate.

Communication Signals in Lizards

Charles Carpenter is professor of zoology at the University of Oklahoma and University of Oklahoma Biological Station, Norman 73019, and curator of reptiles at the Stovall Museum of Science and History. He holds a B.A. degree from Northern Michigan College of Education (now Northern Michigan University), and M.S. and Ph.D. degrees from University of Michigan. He is the recipient of many research grants and several awards, including the Distinguished Alumni Award from Northern Michigan University in 1972, and the Regents' Award for Superior Accomplishment in Research and Creative Activity in 1980. Dr. Carpenter holds memberships in many professional and honorary societies and has held offices in several of them. Since 1947, Dr. Carpenter has authored or coauthored over 100 publications. lhe males of some, probably many kinds of lizards, fight together from rivalry. Thus the arboreal Anolis cristatellus of South America is extremely pugnacious: During the spring and early part of the summer, two adult males rarely meet without a contest. On first seeing one another, they nod their heads up and down three or four times, and at the same time expanding the frill or pouch beneath the throat; their eyes glisten with rage, and after waving their tails from side to side for a few seconds, as if to gather energy, they dart at each other furiously, rolling over and over, and holding firmly with their teeth. Charles Darwin, Descent of Man (1871). The nodding of the head and expansion of the throat pouch by these male lizards may not have been recognized by Darwin as their manner of communicating with each other. I will relate my experiences to show that lizards do communicate with each other by using pushups and head nods and that each species does this in its own way, conveying different types of information. I first became aware of these visual signals while observing a population of fence lizards (Sceloporus undulatus) on the shore of Lake Texoma near the University of Oklahoma Biological Station. The males of this small species performed pushups from the knobs on logs and raised areas along a beach. Each time they performed, the same pattern of pushups was repeated with the same rhythm. Each male performed or signaled in his own territory so that he was visible to other males in their respective territories. Thus it appeared that each male was using the same pushup pattern to communicate to males in adjacent territories his claim to a certain area (Carpenter 1962). During the following few years I acquired different species of iguanid lizards from throughout the Southwestern United States. These were placed in large outside enclosures where they could readily be observed and their behaviors recorded on motion picture film. The males of these different species quickly adapted to these enclosures, set up dominance hierarchies (in lieu of territories), and actively displayed at one another as they would from a territorial lookout. In every instance, each species performed with a different pattern of pushups or head nods which indicated to me that each species had its own set of visual communication signals or language (Carpenter 1967). Over the next ten to fifteen years, with the help of a number of graduate students, it was established that every species of iguanid and agamid lizard for which we obtained data had its own species-specific display-actionpattern (pattern of vertical movements through time). It has not been possible to observe all of the species of these two closely related families of lizards because they are too numerous. The Family Iguanidae ranges all over the Western Hemisphere and its nearby islands, with a genus on the Fiji-Tonga Islands and two genera on Madagascar, while the numerous species of the Agamidae complement this distribution, being found in the Old World from Africa to Australia. However, we have observed representative species from all