Marco Bertamini

University of Padova | UNIPD · Department of General Psychology

This review of symmetry perception has six parts. Psychophysical studies have investigated symmetry perception for over 100 years (part 1). Neuroscientific studies on symmetry perception have accumulated in the last 20 years. Functional MRI and EEG experiments have conclusively shown that regular visual arrangements, such as reflectional symmetry,...

Ponzo is a familiar name in psychology because of the illusion that takes his name. He had a long and productive career in Italy, and some of his work was translated for international journals already in his lifetime. However, few of these papers are available in English. We provide a commentary that considers how his name came to be associated wit...

Although the COVID-19 pandemic has impacted the psychological wellbeing of some people, there is evidence that many have been much less affected. The Ecological Model of Resilience (EMR) may explain why some individuals are not resilient whilst others are. In this study we test the EMR in a comparison of UK survey data collected from the COVID-19 P...

Background: Literature showed that the link between right-wing attitudes and ethnocentric attitudes gets stronger under existential threats, but the role exerted by an impersonal threat – as COVID-19 – on right-wing attitudes is still unclear. Aim: This study aimed to highlight the role of anxiety exerted by the impersonal COVID-19 threat on the r...

Foveal (central) and peripheral vision are strongly interconnected to provide an integrated experience of the world around us. Recently, it has been suggested that there is a feedback mechanism that links foveal and peripheral vision. This peripheral-to-foveal feedback differs from other feedback mechanisms in that during visual processing a novel...

In four experiments we investigated the Solitaire illusion. In this illusion, most observers see as more numerous a set of dots that forms a single central group, compared to dots on the outside of that group. We confirmed and extended the effect to configurations with much higher numerosity than the original and of various colours. Contrary to pre...

Peripheral object discrimination is hindered by a central dynamic mask presented between 150 and 300 ms after stimulus onset. The mask is thought to interfere with task-relevant feedback coming from higher visual areas to the foveal cortex in V1. Fan et al. (2016) supported this hypothesis by showing that the effect of mask can be further delayed i...

Commonly identified trajectories of psychological distress in response to adverse events, like the COVID-19 pandemic, include Resilience, Delayed distress, Recovery and Sustained distress. The current study aimed to analyse these four distinct response patterns during the pandemic using network analysis. Anxiety and depression symptom data collecte...

Introduction: The Italian C19PRC study aimed at describing the psycho-social impact of the pandemic in Italy, giving insight into various aspects, including the psychological (e.g., depression, anxiety) and social (e.g., vaccine hesitancy, authoritarianism) perspectives, with a special focus on the psychosocial factors promoting or hindering Resili...

The way we choose to draw the networks on the plane (layout) is found to be important for the readability of networks by humans. In this study, we examine how different layouts affect our perception of specific properties of small networks of 16 nodes each. We compare a simple grid layout to the planar and force-directed layouts, which are some of...

According to the Foveal Feedback hypothesis, shape information presented in the visual periphery is processed by the foveal cortex (Williams et al., 2008). In their study, Fan et al. (2016) reported an impairment in performance when a foveal distractor was presented between 150-300 ms after target onset. However, it is unclear if this drop in perfo...

Although the COVID-19 pandemic has impacted the psychological wellbeing of some people, there is evidence that many have been much less affected. The Ecological Model of Resilience (EMR) may explain why some individuals are not resilient whilst others are. In this study we test the EMR in a comparison of UK survey data collected from the Covid-19 P...

The extrastriate visual cortex is activated by visual regularity and generates an ERP known as the sustained posterior negativity (SPN). Spatial filter models offer a biologically plausible account of regularity detection based on the spectral properties of an image. These models are specific to reflection and therefore imply that reflectional symm...

Vaccine confidence has emerged as one of the most relevant psychological factors implied in the worldwide affecting the fight against COVID-19—as well as public trust in doctors, medicine, and science. Indeed, the vaccine confidence is crucial to maximize the trust in vaccines and their use for prevention, with several implications for public healt...

It is now possible for scientists to publicly catalogue all the data they have ever collected on one phenomenon. For a decade, we have been measuring a brain response to visual symmetry called the sustained posterior negativity (SPN). Here we report how we have made a total of 6674 individual SPNs from 2215 participants publicly available, along wi...

Individuals tend to prioritize self-relevant information over other-relevant information. Converging empirical evidence indicates that stimuli that are arbitrarily associated with the self are processed more efficiently than stimuli that are arbitrarily associated with stranger identities. In the present study, we tested if a salient perceptual fea...

Background The Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder scale (GAD-7) are self-report measures of major depressive disorder and generalised anxiety disorder. The primary aim of this study was to test for differential item functioning (DIF) on the PHQ-9 and GAD-7 items based on age, sex (males and females), and country....

Observers can quickly estimate the quantity of sets of visual elements. Many aspects of this ability have been studied and the underlying system has been called the Approximate Number Sense (Dehaene, 2011). Specific visual properties, such as size and clustering of the elements, can bias an estimate. For intermediate numerical quantities at low den...

symmetric patterns are generally preferred to less regular patterns. Here, we studied 2D patterns presented as 2D images in the plane, and therefore producing a symmetric pattern on the retina, and the same patterns seen in perspective. This perspective transformation eliminates the presence of perfect symmetry in terms of retinotopic coordinates....

This paper serves to alert IJPDS readers to the availability of a major new longitudinal survey data resource, the COVID-19 Psychological Research Consortium (C19PRC) Study, which is being released for secondary use via the Open Science Framework. The C19PRC Study is a rich and detailed dataset that provides a convenient and valuable foundation fro...

Extrastriate visual areas are strongly activated by image symmetry. Less is known about symmetry representation at object-level rather than image-level. Here we investigated electrophysiological responses to symmetry, generated by amodal completion of partially-occluded polygon shapes. We used a similar paradigm in four experiments (N = 112). A ful...

In humans, extrastriate visual areas are strongly activated by symmetry. However, perfect symmetry is rare in natural visual images. Recent findings showed that when parts of a symmetric shape are presented at different points in time the process relies on a perceptual memory buffer. Does this temporal integration need a retinotopic reference frame...

The information about what one can see and what other people can see from different viewpoints is important. There are circumstances in which adults and children make systematic errors when predicting what is visible from their own or others’ viewpoints. This happens for example when reasoning about mirrors. We explored differences among three deve...

This paper serves to alert IJPDS readers to the availability of a major new longitudinal survey data resource, the COVID-19 Psychological Research Consortium (C19PRC) Study, which is being released for secondary use via the Open Science Framework. The C19PRC Study is a rich and detailed dataset that provides a convenient and valuable foundation fro...

Human perception of symmetry is associated with activation in an extended network of extrastriate visual areas. This activation generates an ERP called the Sustained Posterior Negativity (SPN). In most studies so far, the stimuli have been defined by luminance. We tested whether the SPN is present when stimuli are defined by stereoscopic disparity...

Objective: The Patient Health Questionnaire (PHQ-9) and Generalized Anxiety Disorder scale (GAD-7) are self-report measures of major depressive disorder and generalised anxiety disorder. The primary aim of this study was to test for differential item functioning (DIF) on the PHQ-9 and GAD-7 items based on age, sex (males and females), and country.M...

An Event Related Potential response to visual symmetry, known as the Sustained Posterior Negativity (SPN), is generated whether symmetry is task relevant or not, and whether symmetry is attended or not. However, no study has yet examined interference from concurrent memory tasks. To answer this fundamental question, we investigated whether the SPN...

Despite the severe psychological impact of the COVID-19 pandemic, some individuals do not develop high levels of psychological distress and can be termed resilient. Using the ecological resilience model, we examined factors promoting or hindering resilience in the COVID-19 pandemic. Of the 1034 participants (49.9±16.2 years; females 51.2%) from Ita...

Extrastriate visual areas are strongly activated by image symmetry. Less is known about symmetry representation at object-, rather than image-, level. Here we investigated electrophysiological responses to symmetry, generated by amodal completion of partially-occluded polygon shapes. We used a similar paradigm in four experiments (N=112). A fully-v...

It has been claimed that video gamers possess increased perceptual and cognitive skills compared to non-video gamers. Here, we examined to which extent gaming performance in CS:GO (Counter-Strike: Global Offensive) correlates with visual performance. We tested 94 players ranging from beginners to experts with a battery of visual paradigms, such as...

An Event Related Potential (ERP) component called the Sustained Posterior Negativity (SPN) is generated by regular visual patterns (e.g. vertical reflectional symmetry, horizontal reflectional symmetry or rotational symmetry). Behavioural studies suggest symmetry becomes increasingly salient when the exemplars update rapidly. In line with this, Exp...

A large number of studies have focused on the aesthetic value of smoothly curved objects. By contrast, angular shapes tend to be associated with tertiary qualities such as threat, hardness, loudness, nervousness, etc. The present study focuses on the effect of curvilinearity vs angularity on the aesthetic experience of design artefacts. We used the...

Background Preference for smooth contours occurs for a variety of visual stimuli. However, there are individual differences. Openness to experience, a trait associated with aesthetic appreciation, emotional sensitivity and abstract thinking, correlates with this preference. The evaluation of meaningless stimuli entails automatic associations influe...

Research into the neural basis of symmetry perception has intensified in the last two decades, however the functional role of neural oscillations remains unclear. In previous work (Makin et al., 2014, Wright et al., 2015) examined occipital alpha Event‐Related Desynchronization (alpha ERD). It was concluded that alpha ERD is right lateralized durin...

visual regularities (such as reflectional symmetry) activate the extrastriate visual cortex and generate an Event Related Potential (ERP) called the Sustained Posterior Negativity (SPN). While traditional SPN papers often report a single experiment, we can learn much more by combining data from many experiments. We thus organized and catalogued 249...

Visual regularity activates a network of brain regions in the extrastriate cortex. Previous EEG studies have found that this response scales parametrically with proportion of symmetry in symmetry + noise displays. The parametric symmetry response happens in many tasks, but it is enhanced during active regularity discrimination. However, the origins...

Previous work has shown that symmetrical stimuli are judged as lasting longer than asymmetrical ones, even when actual duration is matched. This effect has been replicated with different methods and stimuli types. We aimed to a) replicate the effect of symmetry on subjective duration, and b) assess whether it was further modulated by the number of...

The COVID-19 pandemic represents a major stressor for the psychological health of people worldwide. In the UK, the COVID19-Psychological Research Consortium Study (C19PRC) launched to evaluate the psychological impact of COVID-19 in the general population and its implications. The project was then extended to Italy and several other countries. This...

Observers can quickly estimate the quantity of sets of visual elements. Many aspects of this ability have been studied and the underlying process has been called the Approximate Number Sense (Dehaene, 2011). Estimates can be biased by specific visual properties, such as size and clustering of the elements. For intermediate numerical quantities and...

Background: The Covid-19 pandemic represents a major stressor for the psychological health of people worldwide. In the UK, the Covid19-Psychological Research Consortium Study (C19PRC) launched to evaluate the psychological impact of Covid-19 in the general population and its implications. The project was then extended to Italy and several other cou...

Neurophysiological studies have shown a strong activation in visual areas in response to symmetry. Electrophysiological (EEG) studies, in particular, have confirmed that amplitude at posterior electrodes is more negative for symmetrical compared to asymmetrical patterns. This response is present even when observers perform tasks that do not require...

It is known that the extrastriate cortex is activated by visual symmetry. This activation generates an ERP component called the Sustained Posterior Negativity (SPN). SPN amplitude increases (i.e. becomes more negative) with repeated presentations. We exploited this SPN priming effect to test whether the extrastriate symmetry response is gated by el...

Visual symmetry perception and symmetry preference have been studied extensively. However, less is known about how people spontaneously scan symmetrical stimuli with their eyes. We thus examined spontaneous saccadic eye movements when participants ( N = 20) observed patterns with horizontal or vertical mirror reflection. We found that participants...

Previous work has shown that symmetrical or regular stimuli are judged as lasting longer than asymmetrical or irregular ones, even when actual duration is matched. This effect has been replicated with different methods and stimuli types, both in the UK and Japan. We aimed to a) replicate the effect of symmetry on subjective duration, and b) assess...

Humans have engaged in artistic and aesthetic activities since the appearance of our species. Our ancestors have decorated their bodies, tools, and utensils for over 100,000 years. The expression of meaning using color, line, sound, rhythm, or movement, among other means, constitutes a fundamental aspect of our species’ biological and cultural heri...

Vision scientists have attempted to classify visual illusions according to certain aspects, such as brightness or spatial features. For example, Piaget proposed that visual illusion magnitudes either decrease or increase with age. Subsequently, it was suggested that illusions are segregated according to their context: real-world contexts enhance an...

Previous research has investigated the neural response to visual symmetry. It is well established that symmetry activates a network of extrastriate visual regions, including V4 and the Lateral Occipital Complex. This symmetry response generates an event-related potential called the sustained posterior negativity (SPN). However, previous work has us...

An ERP component called the Sustained Posterior Negativity (SPN) indexes the brain response to regularity in visual patterns (e.g. vertical reflectional symmetry, horizontal reflectional symmetry or rotational symmetry). However it is unclear if different regularities are coded by independent or overlapping neural populations. Previous work has suc...

Humans have the remarkable ability to rapidly estimate the number of objects in a visual scene without relying on counting, something referred to as the number sense. It has been well documented that the more clustered the elements are, the lower their perceived numerosity is. A recent account of this observation is the crowdinghypothesis, which po...

There is a long history of studies of shape preference using simple abstract two-dimensional shapes. The evidence has confirmed a preference for symmetry, high contrast, and smoothness over asymmetry, low contrast, and angularity. However, the evidence about the role of culture and expertise is inconclusive. We asked a group of 56 expert designers...

The expression big headed is often used to describe narcissists, however is it possible that this term signals a bias in how narcissists perceive themselves? We tested whether narcissistic traits predicted biases in the estimated size and weight of specific body parts, including head circumference and brain weight. In two questionnaire-based studie...

The brain can organize elements into perceptually meaningful gestalts. Visual symmetry is a useful tool to study gestalt formation, and we know that there are symmetry-sensitive regions in the extrastriate cortex. However, it is unclear whether symmetrical gestalt formation happens automatically, whatever the participant's current task is. Does the...

Attention is a process that alters how cognitive resources are allocated, and it allows individuals to efficiently process information at the attended location. The presence of visual or auditory cues in the environment can direct the focus of attention toward certain stimuli even if the cued stimuli are not the individual’s primary target. Samson...

Visiting a museum and seeing an original artwork can be a special experience. We use a survey and a set of hypothetical questions to explore how such experience would be affected by changes in how the artwork is seen. In a first study, participants imagined that they had traveled to see a painting that they particularly like. They discover that it...

People can quickly detect bilateral reflection in an image. This is true when elements of the same luminance are matched on either side of the axis (symmetry) and when they have opposite luminance polarity (anti‐symmetry). Using EEG, we measured the well‐established Sustained Posterior Negativity (SPN) response to symmetry and anti‐symmetry. In one...

Symmetry detection is effortlessly and fast, even within brief presentations of less than 100 milliseconds. Electroencephalographic studies have shown that the brain response to symmetry is automatic and not altered by participant’s task. However, no studies have yet tested whether the symmetry response is altered by the current focus of spatial at...

This handbook is currently in development, with individual articles publishing online in advance of print publication. At this time, we cannot add information about unpublished articles in this handbook, however the table of contents will continue to grow as additional articles pass through the review process and are added to the site. Please note...

Earlier work by one of us examined a historical corpus of portraits and found that artists often paint the subject such that one eye is centred horizontally. If due to psychological mechanisms constraining artistic composition, this eye-centring bias should be detectable also in portraits by non-professionals. However, this finding has been questio...

Curvature along a contour is important for shape perception, and a special role may be played by points of maxima (extrema) along the contour. Angles are discontinuities in curvature, a special case at one extreme of the curvature continuum. We report 4 studies using abstract shapes and comparing polygons (curvature discontinuities at the vertices)...

There are situations in which what is perceived in central vision is different to what is perceived in the periphery, even though the stimulus display is uniform. Here, we studied two cases, known as the Extinction illusion and the Honeycomb illusion, involving small disks and lines, respectively, presented over a large extent of the visual field....

When a person looks at the fingers of their own hand as they line up in depth, the impression may emerge that the little fingers, which are farther away, are located too far and if so they are not part of the same hand. I describe the conditions and suggest this is due to the size difference between fingers (size-distance scaling). A role of size o...

Most people like symmetry, and symmetry has been extensively used in visual art and architecture. In this study, we compared preference for images of abstract and familiar objects in the original format or when containing perfect bilateral symmetry. We created pairs of images for different categories: male faces, female faces, polygons, smoothed ve...

Electrophysiological (EEG) studies of human perception have found that amplitude at posterior electrodes is more negative for symmetrical patterns compared to asymmetrical patterns. This negativity lasts for hundreds of milliseconds and it has been called sustained posterior negativity (SPN). Symmetry activates a network of visual areas, including...