The proper placement of uniform connectedness

Perceptual organization concerns the organization of people’s perception into meaningful, structured entities—often wholes containing parts, with specific interrelationships among the parts as well as specific relationships between the parts and the wholes. It embraces a wide variety of distinct processes, which often occur together in everyday life and lead to interesting perceptual experiences by their interactions. The best-known perceptual organization processes are perceptual grouping and figure-ground organization, which appear to be determined by characteristic principles or laws, such as grouping by proximity, similarity, good continuation, area, convexity, symmetry, and so forth. Other important phenomena of perceptual organization include perceptual multi-stability (i.e., the fact that the same stimulus can give rise to multiple competing percepts that switch over time), visual illusions, the role of reference frames, and the role of context. Gestalt psychology has contributed deep insights into the way people’s perception of the world is organized, although it has also been criticized for its emphasis on subjective experiences and its sometimes vague and non-quantitative descriptions of the Gestalt principles. Because perceptual organization essentially concerns visual awareness, however, phenomenology is needed to describe what is experienced. This ultimately remains the basis for research on perceptual organization even when it is aimed at quantifying the principles of perceptual organization and identifying the neural correlates or mechanisms underlying perceptual organization.

Shape Recognition Inputs To Figure-Ground Organization in Three-Dimensional Displays

In 1912, Max Wertheimer published his paper on phi motion, widely recognized as the start of Gestalt psychology. Because of its continued relevance in modern psychology, this centennial anniversary is an excellent opportunity to take stock of what Gestalt psychology has offered and how it has changed since its inception. We first introduce the key findings and ideas in the Berlin school of Gestalt psychology, and then briefly sketch its development, rise, and fall. Next, we discuss its empirical and conceptual problems, and indicate how they are addressed in contemporary research on perceptual grouping and figure-ground organization. In particular, we review the principles of grouping, both classical (e.g., proximity, similarity, common fate, good continuation, closure, symmetry, parallelism) and new (e.g., synchrony, common region, element and uniform connectedness), and their role in contour integration and completion. We then review classic and new image-based principles of figure-ground organization, how it is influenced by past experience and attention, and how it relates to shape and depth perception. After an integrated review of the neural mechanisms involved in contour grouping, border ownership, and figure-ground perception, we conclude by evaluating what modern vision science has offered compared to traditional Gestalt psychology, whether we can speak of a Gestalt revival, and where the remaining limitations and challenges lie. A better integration of this research tradition with the rest of vision science requires further progress regarding the conceptual and theoretical foundations of the Gestalt approach, which is the focus of a second review article.

Figure-ground organization of an ambiguous pattern can be manipulated by the spatial and temporal frequency content of the two regions of the pattern. Controlling for space-averaged luminance and perceived contrast, we tested patterns in which the two regions of the ambiguous pattern contained sine-wave gratings of 8, 4, 1, or 0.5 cycles per degree (cpd) undergoing on:off flicker at the rates of 0, 3.75, 7.5, or 15 Hz. For a full set of combinations of temporal frequency differences, with each spatial frequency the higher temporal frequency was seen as background for more of the viewing time. For two spatial frequency combinations, 1 and 4 cpd, and 1 and 8 cpd, tested under each of the four temporal frequencies, the lower spatial frequency region was seen as the background for more of the viewing time. When the effects of spatial and temporal frequency were set in opposition, neither was predominant in determining perceptual organization. It is suggested that figure-ground organization may parallel the sustained-transient response characteristics of the visual system.

Perceptual organization in task performance

This article presents a comprehensive integration of current experimental evidence and theories about so-called parapsychological (psi) phenomena. Throughout history, people have reported events that seem to violate the common sense view of space and time. Some psychologists have been at the forefront of investigating these phenomena with sophisticated research protocols and theory, while others have devoted much of their careers to criticizing the field. Both stances can be explained by psychologists' expertise on relevant processes such as perception, memory, belief, and conscious and nonconscious processes. This article clarifies the domain of psi, summarizes recent theories from physics and psychology that present psi phenomena as at least plausible, and then provides an overview of recent/updated meta-analyses. The evidence provides cumulative support for the reality of psi, which cannot be readily explained away by the quality of the studies, fraud, selective reporting, experimental or analytical incompetence, or other frequent criticisms. The evidence for psi is comparable to that for established phenomena in psychology and other disciplines, although there is no consensual understanding of them. The article concludes with recommendations for further progress in the field including the use of project and data repositories, conducting multidisciplinary studies with enough power, developing further nonconscious measures of psi and falsifiable theories, analyzing the characteristics of successful sessions and participants, improving the ecological validity of studies, testing how to increase effect sizes, recruiting more researchers at least open to the possibility of psi, and situating psi phenomena within larger domains such as the study of consciousness. (PsycINFO Database Record

A New Paradigm for Optimizing HIV Intervention Synergy

In our complex acoustic environment, we are confronted with a mixture of sounds produced by several simultaneous sources. However, we rarely perceive these sounds as incomprehensible noise. Our brain uses perceptual organization processes to independently follow the emission of each sound source over time. If the acoustic properties exploited in these processes are well-established, the neurophysiological mechanisms involved in auditory scene analysis remain unclear and have recently raised more interest. Here, we review the studies investigating these mechanisms using electrophysiological recordings from the cochlear nucleus to the auditory cortex, in animals and humans. Their findings reveal that basic mechanisms such as frequency selectivity, forward suppression and multi-second habituation shape the automatic brain responses to sounds in a way that can account for several important characteristics of perceptual organization of both simultaneous and successive sounds. One challenging question remains unresolved: how are the resulting activity patterns integrated to yield the corresponding conscious percepts?

Background: The shoulder region is a common area for pain. The shoulder has the largest range of motion and the most complex mechanical anatomy. The shoulder girdle and related tendons allow for numerous painful disorders to occur. Also, given the overall use of the shoulder, arthritic deformities are all too common. Finally, pain from more complex states such as poststroke shoulder pain and status post total shoulder arthroplasty pain have always been a difficult diagnosis to treat with effectiveness. The innervation to the shoulder predominantly comes from the suprascapular and axillary nerves. Both nerves relatively follow an expected anatomic course and whereby they can be targeted with ultrasound or fluoroscopy. Recently, there has been an increase in evidence that suggests peripheral nerve stimulation can make a difference in these patients with shoulder pain. Objectives: To provide a basic overview of peripheral nerve stimulator placement targeting the axillary and suprascapular nerves. Furthermore, to demonstrate the suggested implantation and current evidence of peripheral nerve stimulation for the treatment of shoulder pain. Study Design: Anatomic clinical review. Methods: A comprehensive review was performed regarding the available literature through targeting articles reporting on the use of peripheral nerve stimulation to treat pain of the shoulder region. Results: We compiled and discuss the current evidence available in treating shoulder pain utilizing peripheral stimulation. The strongest evidence currently is for peripheral nerve stimulation targeting either the axillary or suprascapular nerve, as well as placement targeting the motor points of the deltoid. The most common treated pathology is poststroke shoulder pain. Limitations: Peripheral nerve stimulation has been trialed and is promising for several shoulder pain pathologies; however, there remains a need for large-scale, randomized, placebo-controlled clinical trials to further evaluate the efficacy of most treatments. Much of the current data relies on case reports without randomization or placebo controls. Conclusions: Overall there is fair to moderate evidence for peripheral nerve stimulation to treat shoulder pain in hemiplegic poststroke patients. There is limited evidence when treating other shoulder pain etiologies. Utilizing ultrasound or fluoroscopic guidance, the procedure has proven to be safe allowing proper placement of the electrodes near the target nerves. Considering the high prevalence of shoulder pain from degenerative conditions and overuse, future studies are undoubtedly warranted to evaluate whether peripheral nerve stimulation can modify our treatment algorithm for management of these conditions. Key words: Shoulder pain, suprascapular nerve, axillary nerve, ultrasonography, peripheral nerve stimulation, post stroke shoulder, osteoarthritis, rotator cuff, hemiplegic shoulder pain, adhesive capsulitis

Several studies have shown that the direction in which a visual apparent motion stream moves can influence the perceived direction of an auditory apparent motion stream (an effect known as cross-modal dynamic capture). However, little is known about the role that intramodal perceptual grouping processes play in the multisensory integration of motion information. The present study was designed to investigate the time course of any modulation of the cross-modal dynamic capture effect by the nature of the perceptual grouping taking place within vision. Participants were required to judge the direction of an auditory apparent motion stream while trying to ignore visual apparent motion streams presented in a variety of different configurations. Our results demonstrate that the cross-modal dynamic capture effect was influenced more by visual perceptual grouping when the conditions for intramodal perceptual grouping were set up prior to the presentation of the audiovisual apparent motion stimuli. However, no such modulation occurred when the visual perceptual grouping manipulation was established at the same time as or after the presentation of the audiovisual stimuli. These results highlight the importance of the unimodal perceptual organization of sensory information to the manifestation of multisensory integration.

Every object acquires its shape from some kind of generative process, such as manufacture, biological growth, or self-organization, in response to external forces. Inferring such generative processes from an observed shape is computationally challenging because a given process can lead to radically different shapes, and similar shapes can result from different generative processes. Here, we suggest that in some cases, generative processes endow objects with distinctive statistical features that observers can use to classify objects according to what has been done to them. We found that from the very first trials in an eight-alternative forced-choice classification task, observers were extremely good at classifying unfamiliar objects by the transformations that had shaped them. Further experiments show that the shape features underlying this ability are distinct from Euclidean shape similarity and that observers can separate and voluntarily respond to both aspects of objects. Our findings suggest that perceptual organization processes allow us to identify salient statistical shape features that are diagnostic of generative processes. By so doing, we can classify objects we have never seen before according to the processes that shaped them.

Humans are experts in understanding social environments. What perceptual and cognitive processes enable such competent evaluation of social information? Here we show that environmental content is grouped into units of "social perception", which are formed automatically based on the attentional priority given to social information conveyed by eyes and faces. When asked to segment a clip showing a typical daily scenario, participants were remarkably consistent in identifying the boundaries of social events. Moreover, at those social event boundaries, participants' eye movements were reliably directed to actors' eyes and faces. Participants' indices of attention measured during the initial passive viewing, reflecting natural social behaviour, also showed a remarkable correspondence with overt social segmentation behaviour, reflecting the underlying perceptual organization. Together, these data show that dynamic information is automatically organized into meaningful social events on an ongoing basis, strongly suggesting that the natural comprehension of social content in daily life might fundamentally depend on this underlying grouping process.

Visual perception of complex shape-transforming processes

High rates of turnover among nursing home staff are well documented, especially among nursing assistants who provide 80 percent to 90 percent of the direct care to residents. High staff turnover significantly and negatively impacts a nursing home's ability to provide high-quality care. Current organizational theory and empirical evidence suggest that a supportive workplace promotes satisfaction and retention of workers. A model of staff support in the nursing home is proposed that conceptualizes the nursing home as a supportive social system in which the needs of both staff and residents can be better met.

In three experiments we examined the influence of spatial frequency on perceptual organization. In each experiment a pattern was tested that was ambiguous in terms of figure and ground. In each experiment, the stimuli were 20 variations of the pattern, which were generated by filling the two regions of the pattern with horizontal sine wave gratings differing in spatial frequency. Five spatial frequencies were tested: 0.5, 1, 2, 4, and 8 cycles per degree. The response measure was the percentage of response time one of the regions was seen as the figure. This region was seen as the figure a higher percentage of the time in those stimuli where it contained the relatively higher spatial frequency sine wave grating compared with those stimuli where it contained the relatively lower spatial frequency sine wave grating.