Combining and segmenting geometric shapes into parts depending on symmetry type: Evidence from children and adults.

Symmetry is an important geometric feature that affects object segmentation into parts, though De Winter and Wagemans note that partly occluded objects can still be identified by the remaining visible parts. In two sets of experiments with children (n = 31, age 7-11, M = 8.8, SD = 1.4) and adults (n = 19, age 17-57, M = 30.4, SD = 12.6), we used 13 basic geometric figures distinguished by symmetry types to test how they are naturally segmented or combined and what the developmental impacts are on the segmentation and combination. In the first experiment, participants were asked to cut figures into two along a straight line; in the second experiment, participants had to create five sets of connected two-figure combinations where overlapping figures were allowed. The results confirmed the importance of the symmetry axis in both tasks. Other relevant criteria were dividing into half, maximal/minimal curvature, and use of edges or corners for reference. This study allows comparisons of the impact of symmetry type on the segmentation and combining of geometric figures and indicates developmental differences between children and adults.

Spatial communication systems across languages reflect universal action constraints.

The extent to which languages share properties reflecting the non-linguistic constraints of the speakers who speak them is key to the debate regarding the relationship between language and cognition. A critical case is spatial communication, where it has been argued that semantic universals should exist, if anywhere. Here, using an experimental paradigm able to separate variation within a language from variation between languages, we tested the use of spatial demonstratives-the most fundamental and frequent spatial terms across languages. In n = 874 speakers across 29 languages, we show that speakers of all tested languages use spatial demonstratives as a function of being able to reach or act on an object being referred to. In some languages, the position of the addressee is also relevant in selecting between demonstrative forms. Commonalities and differences across languages in spatial communication can be understood in terms of universal constraints on action shaping spatial language and cognition.

Figure-Ground Segmentation and Biological Motion Perception in Peripheral Visual Field.

Biological motion perception is a specific type of perceptual organization, during which a clear image of a moving human body is perceptually generated in virtue of certain core light dots representing the major joint movements. While the processes of biological motion perception have been studied extensively for almost a century, there is still a debate on whether biological motion task performance can be equally precise across all visual field or is central visual field specified for biological motion perception. The current study explores the processes of biological motion perception and figure-ground segmentation in the central and peripheral visual field, expanding the understanding of perceptual organization across different eccentricities. The method involved three different tasks of visual grouping: (1) a static visual grouping task, (2) a dynamic visual grouping task, and (3) a biological motion detection task. The stimuli in (1) and (2) were generated from 12-13 dots grouped by proximity and common fate, and, in (3), light dots representing human motion. All stimuli were embedded in static or dynamics visual noise and the threshold value for the number of noise dots in which the elements could still be grouped by proximity and/or common fate was determined. The results demonstrate that biological motion can be differentiated from the scrambled set of moving dots in a more intensive visual noise than static and dynamic visual grouping tasks. Furthermore, in all three visual tasks (static and dynamic grouping, and biological motion detection) the performance was significantly worse in the periphery than in the central visual field, and object magnification could not compensate for the reduced performance in any of the three grouping tasks. The preliminary results of nine participants indicate that (a) human motion perception involves specific perceptual processes, providing the high-accuracy perception of the human body and (b) the processes of figure-ground segmentation are governed by the bottom-up processes and the best performance can be achieved only when the object is demonstrated in the central visual field.

From perceptual organization to visual illusions and back.

In modern vision science, illusions are compelling phenomena useful as tools to explore vision under limiting psychophysical conditions. Illusions manifest at least two issues that challenge scientists. The first issue is related to the definition of illusion and to the complexity of the mismatch between the geometrical/physical and the phenomenal domains. The second issue concerns two different meanings of the term "illusion," respectively related to the demonstration of the illusion through the mismatch between domains and to the phenomenal illusoriness, i.e., the perception of something having the nature of an illusion, unreal, ambiguous, fallacious, and deceptive. In this work, we explored the notion of illusion starting from the principles of perceptual organization as described by Gestalt psychologists. On the basis of several phenomenal conditions, step by step, we suggested some new hypotheses, whose purpose was to answer the following questions: what is physical and what is phenomenal? Is there and, if any, what is the dividing line between illusions and non-illusions? Is it true that illusions are rare phenomena? Why do illusions exist? What is their perceptual and evolutionist role? These questions and the related issues were phenomenally discussed by deepening and extending the notion of perceptual organization and by exploring the biological implications of both illusions and illusoriness. On the basis of our results, the perception of illusion and illusoriness can be considered as a further challenge for vision scientists useful to shed new insights within the biological meanings of visual perception and within the no-man land between sensory and cognitive processes that elicit visual consciousness not fully explored yet.

Similarity and Dissimilarity in Perceptual Organization: On the Complexity of the Gestalt Principle of Similarity.

The main purpose of this work is to explore the Gestalt principle of similarity and to demonstrate that the use of this term alone is not sufficient to understand the dynamics of grouping fully and correctly. More generally, this work aims to show that the Gestalt principle of similarity alone is not sufficient for a full understanding of perceptual organization occurring both in the classical and mostly in the new phenomena here presented. Limits and incompleteness of the similarity principle have suggested the basic, more general and stronger role of dissimilarity in perceptual grouping under a large variety of conditions. Dissimilarity was shown as a basic principle of figure-ground segregation, as a tool useful to create at will new groups and visual objects within patterns where they are totally invisible, as an attribute that is able to accentuate different shape components within the same object, as a way to distort shapes and create visual illusions, but also to reduce or annul them and, finally, to decompose, ungroup and reshape single objects. The results demonstrated the necessity to introduce a principle of dissimilarity that is complementary to similarity as already studied by Gestalt psychologists.

Gaze Parameters in the Analysis of Ambiguous Geometric Shapes.

This study explores perceptual organisation and shape perception when viewing a tetragon and an additional element (a dot) that is located at varying positions and distances next to the tetragon. The aim of the study is to determine the factors that can alter the interpretation of object configuration and impact whether the presented tetragon is perceived as a diamond or a square. Methods used in this study are a forced-choice task as a subjective measurement and eye tracking as an objective measurement of perceptual processes. Overall, 31 stimuli were presented to the participants: a tetragon in two different sizes with an additional element (a dot) located inside or outside the object at three different positions at three distances. The results indicate significant changes in shape perception, depending on the location of the additional element. The results are complemented with eye movement analysis indicating that as the distance between the elements increases, there is a higher probability of either of the two shape interpretations and the gaze is less likely to be directed to the area between the stimuli. Furthermore, the subjective perception of shape is codetermined by the shape perception when the tetragon is presented without the additional element.

Ideational Fluency in Patients with Rheumatoid Arthritis.

BACKGROUND: Neuropsychiatric symptoms have been well documented in several systemic inflammatory conditions, for example, systemic lupus erythematosus (SLE). Increased prevalence of cognitive decline and psychiatric issues has been reported in patients with rheumatoid arthritis (RA). However, there is limited evidence of which exact cognitive domains are affected and to what degree. AIM: To test the performance of cognition in the domain of ideational fluency (Thing Categories Test in particular) in patients with RA and compare the results with the general population and to the results with cognitive and depression screening scores in both groups. METHODS: Patient Health Questionnaire 9 (PHQ-9), Generalized Anxiety Disorder 7 (GAD-7) assessment, Montreal Cognitive Assessment (MoCA), and Thing Categories Test (TCT) were used to evaluate patients with RA, as well as the control group. RESULTS: Twenty patients with RA and 20 controls were tested, with 7 and 4 men, and 13 and 16 women in the study and control group, respectively. Average scores in TCT at three minutes were 7.50 (IQR6.0-10.0) and 6.0 (IQR3.0-8.0) for category "blue"; 17.50 (IQR15.0-19.0) and 16.0 (10.0-18.0) for category "round" in the control and study group, respectively. A statistically significant difference was established between the study and the control group in TCT for the category "blue" (p<0.025). The average score for GAD7 was 2.0 (IQR 0.0-5.75) and 3.0 (IQR0.50-6.00) in the control and study group, respectively. The average score for PHQ-9 was 2.0 (IQR0.25-4.75) and 4.0 (IQR2.00-5.50) in the control and study group, respectively. Finally, the average score for the MoCA scale was 27.0 (IQR25.25-28.00) and 26.0 (IQR23.50-28.00) in the control and study group, respectively. CONCLUSION: Preliminary evidence suggests that RA at least partially affects the cognitive domain of ideational fluency. However, further research with larger experimental groups is needed to provide more conclusive evidence.

Acquisition of spatial knowledge in different urban areas: evidence from a survey analysis of adolescents.

We herein explore the perception of the geographic environment and analyse the mechanisms that constrain the cognitive processing of spatial information in general. Our guiding theoretical background assumption is that the structure of the spatial environment is a cognitively robust and mutually constrained threefold system relating (1) cognitive topology (comprised of a path and place structure of spatial information and constrained by reference frame-based factors), (2) experience-based functional knowledge (including the effects of socio-economic factors, frequency and familiarity) and (3) linguistic representations (primarily encoded in the prepositional system of a natural language). Here, we focus on (2), i.e. the effect of functional knowledge on the process of acquiring spatial knowledge. We empirically tested adolescents aged 12­17 years to explore the interaction between frequency, familiarity and functional knowledge from a developmental point of view. The social factors we explore are precisely defined and parameterized in our results (exposure to a particular urban area, place of residence, gender, age and factors relating to the environmental and social quality of the local area). Our research shows that there are divergences between the so called objective topology and the cognitive typology of the urban environment that are significantly constrained by intensity of interactions with environment, number of functionally significant places within particular area and age from a developmental perspective in terms of spatial knowledge acquisition.