One characteristic of human visual perception is the presence of Gestalt phenomena,' that is, that the whole is something other than the sum of its parts. A natural question is whether image-recognition networks show similar effects. Our paper investigates one particular type of Gestalt phenomenon, the law of closure, in the context of a feedforward image classification neural network (NN). This is a robust effect in human perception, but experiments typically rely on measurements (e.g., reaction time) that are not available for artificial neural nets. We describe a protocol for identifying closure effect in NNs, and report on the results of experiments with simple visual stimuli. Our findings suggest that NNs trained with natural images do exhibit closure, in contrast to networks with randomized weights or networks that have been trained on visually random data. Furthermore, the closure effect reflects something beyond good feature extraction; it is correlated with the network's higher layer features and ability to generalize.
The key idea of the Gestalt psychology school is that we perceive individual sensory stimuli as meaningful wholes @cite_19 . Further, the Gestalt psychologists maintained that when sensory elements are combined, the elements form a new pattern or configuration. For example, when you hear musical notes, a melody emerges from their combinations, something that did not exist in individual elements. In other words, the whole is different from the sum of its parts @cite_42 . This overarching idea explains many phenomena of human perception @cite_19 , one of which is illusory contours (set Illusory in Fig. ); the brain has a need to see familiar simple objects and has a tendency to create a whole'' image from individual elements.
@cite_19 @cite_42
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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. properly with psychophysics, the hundred-year-old discipline con cerned with the responses that organisms make to the energies of the environment. We live in a restless world of energetic forces, some of which affect us and some of which, like radio waves, impinge upon us and pass unnoticed because we have no sense organs able to transduce them. But we see lights, hear sounds, taste substances, and smell vapors; and it is these elementary facts of psychophysics that stir our interest in the anatomy and physiology of the mechanisms that make sensation possible. An orderly and systematic account of sensory communication must include a delineation of what is perceived as well as an explanation of how perception is accomplished. In this sense, psychophysics defines the challenge : it tells what the organism can do and it asks those who are inspired by such mysteries to try, with scalpel, electrode, and test tube, to advance our understanding of how such wonders are performed. It must be confessed at the outset that psychophysics has often failed to do its part of the job with distinction. Its task is not easy. For one thing, long-standing prejudices, derived in great measure from a chronic dualistic metaphysics, have triggered a variety of stubborn objections whenever it has been proposed that sensation may be amenable to orderly and quantitative investigation. You cannot, the objectors complain, measure the inner, private, subjective strength of a sensation. Perhaps not, in the sense the objectors have in mind, but in a different and very useful sense the strength of a sensation can, as we shall see, be fruitfully quantified. We must forego arguments about the private life of the mind and ask sensible objective questions about the input-output relations of sensory transducers as these relations are disclosed in the behavior of experimental organisms, whether men or animals. Another difficulty is that psychophysics had an unfortunate child hood. Although Plateau, in the 1850's, made a half-hearted attempt to suggest the proper form of the function relating apparent sensory intensity to stimulus intensity, he was shouted down by Fechner, who saddled the infant discipline with the erroneous "law" that bears his Summary Our nervous system is confronted with a barrage of sensory stimuli, but neural resources are limited and not all stimuli can be processed to the same extent. Mechanisms exist to bias attention toward the particularly salient events, thereby providing a weighted representation of our environment [1]. Our understanding of these mechanisms is still limited, but theoretical models can replicate such a weighting of sensory inputs and provide a basis for understanding the underlying principles [2, 3]. Here, we describe such a model for the auditory system—an auditory saliency map. We experimentally validate the model on natural acoustical scenarios, demonstrating that it reproduces human judgments of auditory saliency and predicts the detectability of salient sounds embedded in noisy backgrounds. In addition, it also predicts the natural orienting behavior of naive macaque monkeys to the same salient stimuli. The structure of the suggested model is identical to that of successfully used visual saliency maps. Hence, we conclude that saliency is determined either by implementing similar mechanisms in different unisensory pathways or by the same mechanism in multisensory areas. In any case, our results demonstrate that different primate sensory systems rely on common principles for extracting relevant sensory events. Gestalt phenomena have long resisted quantification In the spirit of Gestalt field theory, we propose a theory that predicts the probability of grouping by proximity in the six kinds of dot lattices (hexagonal, rhombic, square, rectangular, centered rectangular, and oblique) We claim that the unstable perceptual organization of dot lattices is caused by competing forces that attract each dot to other dots in its neighborhood We model the decline of these forces as a function of distance with an exponential decay function This attraction function has one parameter, the attraction constant Simple assumptions allow us to predict the entropy of the perceptual organization of different dot lattices We showed dot lattices tachistoscopically to 7 subjects, and from the probabilities of the perceived organizations, we calculated the entropy of each lattice for each subject The model fit the data exceedingly well The attraction constant did not vary much over subjects