Influence of Visual Motion,Suggestion, and Illusory Motion on Self-Motion Perception in the Horizontal Plane

A moving visual field can induce the feeling of self-motion or vection. Illusory motion from static repeated asymmetric patterns creates a compelling visual motion stimulus, but it is unclear if such illusory motion can induce a feeling of self-motion or alter self-motion perception. In these experiments, human subjects reported the perceived direction of self-motion for sway translation and yaw rotation at the end of a period of viewing set visual stimuli coordinated with varying inertial stimuli. This tested the hypothesis that illusory visual motion would influence self-motion perception in the horizontal plane. Trials were arranged into 5 blocks based on stimulus type: moving star field with yaw rotation, moving star field with sway translation, illusory motion with yaw, illusory motion with sway, and static arrows with sway. Static arrows were used to evaluate the effect of cognitive suggestion on self-motion perception. Each trial had a control condition; the illusory motion controls were altered versions of the experimental image, which removed the illusory motion effect. For the moving visual stimulus, controls were carried out in a dark room. With the arrow visual stimulus, controls were a gray screen. In blocks containing a visual stimulus there was an 8s viewing interval with the inertial stimulus occurring over the final 1s. This allowed measurement of the visual illusion perception using objective methods. When no visual stimulus was present, only the 1s motion stimulus was presented. Eight women and five men (mean age 37) participated. To assess for a shift in self-motion perception, the effect of each visual stimulus on the self-motion stimulus (cm/s) at which subjects were equally likely to report motion in either direction was measured. Significant effects were seen for moving star fields for both translation (p = 0.001) and rotation (p<0.001), and arrows (p = 0.02). For the visual motion stimuli, inertial motion perception was shifted in the direction consistent with the visual stimulus. Arrows had a small effect on self-motion perception driven by a minority of subjects. There was no significant effect of illusory motion on self-motion perception for either translation or rotation (p>0.1 for both). Thus, although a true moving visual field can induce self-motion, results of this study show that illusory motion does not.     

Perception of Elasticity in the Kinetic Illusory Object with Phase Differences in Inducer Motion

Background

It is known that subjective contours are perceived even when a figure involves motion. However, whether this includes the perception of rigidity or deformation of an illusory surface remains unknown. In particular, since most visual stimuli used in previous studies were generated in order to induce illusory rigid objects, the potential perception of material properties such as rigidity or elasticity in these illusory surfaces has not been examined. Here, we elucidate whether the magnitude of phase difference in oscillation influences the visual impressions of an object''s elasticity (Experiment 1) and identify whether such elasticity perceptions are accompanied by the shape of the subjective contours, which can be assumed to be strongly correlated with the perception of rigidity (Experiment 2).

Methodology/Principal Findings

In Experiment 1, the phase differences in the oscillating motion of inducers were controlled to investigate whether they influenced the visual impression of an illusory object''s elasticity. The results demonstrated that the impression of the elasticity of an illusory surface with subjective contours was systematically flipped with the degree of phase difference. In Experiment 2, we examined whether the subjective contours of a perceived object appeared linear or curved using multi-dimensional scaling analysis. The results indicated that the contours of a moving illusory object were perceived as more curved than linear in all phase-difference conditions.

Conclusions/Significance

These findings suggest that the phase difference in an object''s motion is a significant factor in the material perception of motion-related elasticity.     

Evoked activity of the human brain during perception of illusory stimuli

Evoked activity of the human brain was studied in 19 right-handed men during the perception of illusory images in Go/NoGo tasks. It was found that the recognition of illusory images was associated with changes in the amplitudes of both early (P1 and P2) and late (P3a and P3b) components of the evoked potentials and with an increase in the latencies of the late components recorded from the occipital, central, and frontal cortical areas, which could be explained by the necessity to store a template in the memory, compare a perceived image with the template, and prepare and execute (or inhibit) a motor response. At the same time, the operation of the brain was more differentiated during the NoGo task compared to the Go task.     

Scale-freeness of dominant and piecemeal perceptions during binocular rivalry

When two eyes are simultaneously stimulated by two inconsistent images, the observer’s perception switches between the two images every few seconds such that only one image is perceived at a time. This phenomenon is named binocular rivalry (BR). However, sometimes the perceived image is a piecemeal mixed of two stimuli known as piecemeal perceptions. In this study, a BR task was designed in which orthogonal gratings are presented to the two eyes. The subjects were trained to report 3 states: dominant perceptions (two state matching to perceived grating orientation) and the piecemeal perceptions (third state). We explored the scale-freeness of the BR percept durations considering the two dominant monocular states as well as the piecemeal transition state using detrended fluctuation analysis. Our results reproduced the previous finding of memory in the perceptual switches between the monocular perception states. Moreover, we showed that such memory also exists in the transitory periods of dichoptic piecemeal perceptions. These results support our hypothesis that the pool of unstable piecemeal perceptions could be regarded as separate multiple low-depth basin in the perceptual state landscape. Likewise, the transitions from these piecemeal state basins and stable monocular state basins are faced with resistance. Therefore there is inertia and memory (i.e. positive serial correlation) for the piecemeal dichoptic perception states as well as the monocular states.     

Knowing,understanding and practising democratic citizenship: an investigation of the role of religion among Muslim,Christian and non-religious adolescents

The aim of this study is to examine the relation between religiosity and civic competences required to practise democratic citizenship. We compare non-religious, Christian and Muslim adolescents in the Netherlands to see whether (a) there is a relation between religion and civic competences, and (b) whether this differs depending on religious denomination. In the public debate, the reconcilability of Islamic beliefs and democratic citizenship is often questioned, but the relation between the two lacks empirical support. Results from analyses on data of 364 adolescents in the Netherlands indicate that religious adolescents have more developed democratic competences than non-religious adolescents. This is the case both for Christian and Muslim adolescents. The strength of religiosity does not play a role in predicting civic competences. Importantly, no differences are found between the civic competences of Muslim and Christian youth.     

How the religious context affects the relationship between religiosity and attitudes towards immigration

This article approaches two shortcomings in previous research on religiosity and prejudice: (1) the lack of cross-country comparative studies; and (2) a failure to consider any moderating effects of religious contexts. We examine whether the relationship between religiosity and anti-immigration attitudes varies depending on religious contexts in Europe, and we find two things. First, strongly religious people are on average less likely to oppose immigration than non-religious people. Second, different religious contexts moderate the religiosity–attitude relationship in that religious people in Protestant countries and in countries with a low proportion of majority adherents are more tolerant than religious people in Catholic countries and in religiously homogenous countries. State policies also matter in that religious people are more negative where the government favours the majority religion. This calls into question the taken-for-granted understanding of religiosity and out-group attitudes found in the USA.     

A motion illusion reveals mechanisms of perceptual stabilization

Visual illusions are valuable tools for the scientific examination of the mechanisms underlying perception. In the peripheral drift illusion special drift patterns appear to move although they are static. During fixation small involuntary eye movements generate retinal image slips which need to be suppressed for stable perception. Here we show that the peripheral drift illusion reveals the mechanisms of perceptual stabilization associated with these micromovements. In a series of experiments we found that illusory motion was only observed in the peripheral visual field. The strength of illusory motion varied with the degree of micromovements. However, drift patterns presented in the central (but not the peripheral) visual field modulated the strength of illusory peripheral motion. Moreover, although central drift patterns were not perceived as moving, they elicited illusory motion of neutral peripheral patterns. Central drift patterns modulated illusory peripheral motion even when micromovements remained constant. Interestingly, perceptual stabilization was only affected by static drift patterns, but not by real motion signals. Our findings suggest that perceptual instabilities caused by fixational eye movements are corrected by a mechanism that relies on visual rather than extraretinal (proprioceptive or motor) signals, and that drift patterns systematically bias this compensatory mechanism. These mechanisms may be revealed by utilizing static visual patterns that give rise to the peripheral drift illusion, but remain undetected with other patterns. Accordingly, the peripheral drift illusion is of unique value for examining processes of perceptual stabilization.     

Rewarding the good and punishing the bad: The role of karma and afterlife beliefs in shaping moral norms

Moralizing religions encourage people to anticipate supernatural punishments for violating moral norms, even in anonymous interactions. This is thought to be one way large-scale societies have solved cooperative dilemmas. Previous research has overwhelmingly focused on the effects of moralizing gods, and has yet to thoroughly examine other religious moralizing systems, such as karma, to which more than a billion people subscribe worldwide. In two pre-registered studies conducted with Chinese Singaporeans, we compared the moralizing effects of karma and afterlife beliefs of Buddhists, Taoists, Christians, and the non-religious. In Study 1 (N = 582), we found that Buddhists and Taoists (karmic religions) judge individual actions as having greater consequences in this life and the next, compared to Christians. Pointing to the specific role of karma beliefs in these judgements, these effects were replicated in comparisons of participants from the non-karmic religions/groups (Christian and non-religious) who did or did not endorse karma belief. Study 2 (N = 830) exploited religious syncretism in this population by reminding participants about either moral afterlife beliefs (reincarnation or heaven/hell), ancestor veneration beliefs, or neither, before assessing norms of generosity in a series of hypothetical dictator games. When reminded of their ancestor veneration beliefs, Buddhists and Taoists (but not Christians) endorsed parochial prosocial norms, expressing willingness to give more to their family and religious group than did those in the control condition. Moral afterlife beliefs increased generosity to strangers for all groups. Taken together, these results provide evidence that different religious beliefs can foster and maintain different prosocial and cooperative norms.     

Fooling the Eyes: The Influence of a Sound-Induced Visual Motion Illusion on Eye Movements

The question of whether perceptual illusions influence eye movements is critical for the long-standing debate regarding the separation between action and perception. To test the role of auditory context on a visual illusion and on eye movements, we took advantage of the fact that the presence of an auditory cue can successfully modulate illusory motion perception of an otherwise static flickering object (sound-induced visual motion effect). We found that illusory motion perception modulated by an auditory context consistently affected saccadic eye movements. Specifically, the landing positions of saccades performed towards flickering static bars in the periphery were biased in the direction of illusory motion. Moreover, the magnitude of this bias was strongly correlated with the effect size of the perceptual illusion. These results show that both an audio-visual and a purely visual illusion can significantly affect visuo-motor behavior. Our findings are consistent with arguments for a tight link between perception and action in localization tasks.     

THINKING THROUGH IMAGES: KASTOM AND THE COMING OF THE BAHA'IS TO NORTHERN NEW IRELAND, PAPUA NEW GUINEA

We can learn a lot about religious ideas by studying not just the impact on them of missionization but also how religious beliefs and practices are translated into local religious forms. In this article I draw attention to the case of the Baha'i faith in the Nalik area of northern New Ireland (Papua New Guinea). In discussing how the faith became strongly associated with the ability to harness ancestral power, I argue that this relationship emerged through Nalik people's ability to think through images, in other words through transforming forms in order to create new understandings. This study not only underlines the importance of localized studies into the technology of image production but also fills a gap in anthropological studies that, up until now, have systematically ignored the Baha'i movement and its place in the contemporary Pacific.     

Age related size invariance in perception of illusory and fragmented contours

We investigated invariant perception to sizes of images. Observers were schoolmates of 7-17 years and adults. Two types of stimuli were used: fragmented line drawing of common objects and discs with deleted sectors, which represented illusory Kanizsa contours when discs were in particular positions. In experiments with fragmented images, we found an improvement in image recognition with observers' age, increasing up to 13-14 years. The probability of recognition of fragmented line drawings increased significantly with decreasing stimulus size for children of 7-12 years, indicating that size invariance at recognition for fragmented line drawings was absent in these children. However, size invariance was found for observers of 13-17 years and for adults in this task. At Kanizsa illusion appearance, the ratio of the separation between discs and disc diameter was smaller when we used larger disc diameters. This ratio increased with increasing age of observers. Obtained results provide evidence for the absence of size invariance when perceiving the Kanizsa illusion in our experimental conditions.     

The Study of Visual Thinking

Man perceives the world not only as it really is but also as it might be. In other words, perception is productive as well as reproductive, and the visual system contains mechanisms that generate new images. A study of these mechanisms and the principles of image generation is the subject of a special field in psychology which has recently been given the name "visual thinking" (1).     

763. GUNDELIA TOURNEFORTII

Gundelia tournefortii L. (Compositae: Gundelieae) is described and illustrated, and its strange inflorescence morphology highlighted. The history of the discovery of this fascinating plant is covered from one of the first natural history collections made in the late 16th century in the Levant. The problematic taxonomy of this genus is discussed, both supragenerically and infragenerically. The species has very rarely been cultivated throughout its recent history, making a commentary on its cultivation and propagation a little difficult. The wide range of uses cover a history dating back at least 10,000 years, from the Neolithic sites of Iraq and Turkey, to its present day usage in the region. The importance of herbarium specimen data, as well as literature, for the ethnobotany of taxa is emphasized. A possible biblical connection is commented on in relation to the Shroud of Turin.     

A hidden sensory function for motor cortex

Sensory perception has traditionally been attributed to the activation of sensory cortices. However, by inducing an illusory perception of movement, Naito and colleagues show in this issue of Neuron that the illusory perception of movement is related to activation of primary motor cortex.     

Age-related size invariance in perception of illusory and fragmented contours

We investigated invariant perception to sizes of images. Observers were secondary school students aged 7–17 years and adults. Two types of stimuli were used: fragmented line drawing of common objects and discs with deleted sectors which represented illusory Kanizsa contours, when discs were in particular positions. In experiments with fragmented images, we found an improvement in image recognition with observer’s age, increasing up to 13–14 years. The probability of recognition of fragmented line drawings increased significantly with decreasing stimulus size for children aged 7–12 years, indicating that size invariance at recognition for fragmented line drawings was absent in these children. However, size invariance was found for observers aged 7–12 years and for adults in this task. Upon the Kanizsa illusion appearance, the ratio of the separation between discs and disc diameter was smaller when we used larger disc diameters. This ratio increased with increasing age of observers. The obtained results provide evidence for the absence of size invariance when perceiving the Kanizsa illusion under our experimental conditions.     

Seeing more than meets the eye: processing of illusory contours in animals

This review article illustrates that mammals, birds and insects are able to perceive illusory contours. Illusory contours lack a physical counterpart, but monkeys, cats, owls and bees perceive them as if they were real borders. In all of these species, a neural correlate for such perceptual completion phenomena has been described. The robustness of neuronal responses and the abundance of cells argue that such neurons might indeed represent a neural correlate for illusory contour perception. The internal state of an animal subject (i.e., alert and behaving) seems to be an important factor when correlating neural activity with perceptual phenomena. The fact that the neural network necessary for illusory contour perception has been found in relatively early visual brain areas in all tested animals suggests that bottom-up processing is largely sufficient to explain such perceptual abilities. However, recent findings in monkeys indicate that feedback loops within the visual system may provide additional modulation. The detection of illusory contours by independently evolved visual systems argues that processing of edges in the absence of contrast gradients reflects fundamental visual constraints and not just an artifact of visual processing.     

The Collaborative Image of The City: Mapping the Inequality of Urban Perception

A traveler visiting Rio, Manila or Caracas does not need a report to learn that these cities are unequal; she can see it directly from the taxicab window. This is because in most cities inequality is conspicuous, but also, because cities express different forms of inequality that are evident to casual observers. Cities are highly heterogeneous and often unequal with respect to the income of their residents, but also with respect to the cleanliness of their neighborhoods, the beauty of their architecture, and the liveliness of their streets, among many other evaluative dimensions. Until now, however, our ability to understand the effect of a city''s built environment on social and economic outcomes has been limited by the lack of quantitative data on urban perception. Here, we build on the intuition that inequality is partly conspicuous to create quantitative measure of a city''s contrasts. Using thousands of geo-tagged images, we measure the perception of safety, class and uniqueness; in the cities of Boston and New York in the United States, and Linz and Salzburg in Austria, finding that the range of perceptions elicited by the images of New York and Boston is larger than the range of perceptions elicited by images from Linz and Salzburg. We interpret this as evidence that the cityscapes of Boston and New York are more contrasting, or unequal, than those of Linz and Salzburg. Finally, we validate our measures by exploring the connection between them and homicides, finding a significant correlation between the perceptions of safety and class and the number of homicides in a NYC zip code, after controlling for the effects of income, population, area and age. Our results show that online images can be used to create reproducible quantitative measures of urban perception and characterize the inequality of different cities.     

Isonymy and the structure of the Provençal-Italian ethnic minority

Surnames were obtained for the second half of the 20th century from civil and religious marriage registers on fifteen Proven?al-Italian and five Italian villages of Cuneo Province, Italy. To insert in the analysis an outward comparison, surnames from two Italian villages of Turin Province, one parish of Turin, one village of Alessandria Province and one village of Asti Province were also collected. Ethnicity does not seem to be the main factor affecting the present genetic structure of the Proven?al-Italians. They are an open community, and evidence the end of the genetic isolation of the alpine populations.     

Music alters visual perception

Background

Visual perception is not a passive process: in order to efficiently process visual input, the brain actively uses previous knowledge (e.g., memory) and expectations about what the world should look like. However, perception is not only influenced by previous knowledge. Especially the perception of emotional stimuli is influenced by the emotional state of the observer. In other words, how we perceive the world does not only depend on what we know of the world, but also by how we feel. In this study, we further investigated the relation between mood and perception.

Methods and Findings

We let observers do a difficult stimulus detection task, in which they had to detect schematic happy and sad faces embedded in noise. Mood was manipulated by means of music. We found that observers were more accurate in detecting faces congruent with their mood, corroborating earlier research. However, in trials in which no actual face was presented, observers made a significant number of false alarms. The content of these false alarms, or illusory percepts, was strongly influenced by the observers'' mood.

Conclusions

As illusory percepts are believed to reflect the content of internal representations that are employed by the brain during top-down processing of visual input, we conclude that top-down modulation of visual processing is not purely predictive in nature: mood, in this case manipulated by music, may also directly alter the way we perceive the world.     

How to live together with our differences

Analysing Paul Bert's contributions to the creation of a public, secular and compulsory school and also the meaning of the French 1905 law which separates Churches from the State, this contribution suggests to enlarge the concept of secularity from a religious to a non-religious acception, which opens on a new conception of the European Union.