It is well known that motion facilitates the visual perception of solid object shape, particularl... more It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven") for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition...
Thesis (Ph. D.)--Ohio State University, 1997. Includes bibliographical references (leaves 90-95).... more Thesis (Ph. D.)--Ohio State University, 1997. Includes bibliographical references (leaves 90-95). Advisor: James T. Todd, Dept. of Psychology.
Is it possible for humans to navigate in the natural environment wherein the path taken between v... more Is it possible for humans to navigate in the natural environment wherein the path taken between various destinations is 'optimal' in some way? In the domain of optimization this challenge is traditionally framed as the "Traveling Salesman Problem" (TSP). What strategies and ecological considerations are plausible for human navigation? When given a two-dimensional map-like presentation of the destinations, participants solve this optimization exceptionally well (only 2-3% longer than optimum)^1, 2^. In the following experiments we investigate the effect of effort and its environmental affordance on navigation decisions when humans solve the TSP in the natural environment. Fifteen locations were marked on two outdoor landscapes with flat and varied terrains respectively. Performance in the flat-field condition was excellent (∼6% error) and was worse but still quite good in the variable-terrain condition (∼20% error), suggesting participants do not globally pre-plan r...
Humans are generally remarkably good at inferring 3D shape from distorted patterns of reflections... more Humans are generally remarkably good at inferring 3D shape from distorted patterns of reflections on mirror-like objects (Fleming et al, 2004). However, there are conditions in which shape perception fails (complex planar reliefs under certain illuminations; Faisman and Langer, 2013). A good theory of shape perception should predict failures as well as successes of shape perception, so here we sought to map out systematically the conditions under which subjects fail to estimate shape from specular reflections and to understand why. To do this, we parametrically varied the spatial complexity (spatial frequency content) of both 3D relief and illumination, and measured under which conditions subjects could and could not infer shape. Specifically, we simulated surface reliefs with varying spatial frequency content and rendered them as perfect mirrors under spherical harmonic light probes with varying frequency content. Participants viewed the mirror-like surfaces and performed a depth-discrimination task. On each trial, the participants’ task was to indicate which of two locations on the surface—selected randomly from a range of relative depth differences on the object’s surface—was higher in depth. We mapped out performance as a function of both the relief and the lighting parameters. Results show that while participants were accurate within a given range for each manipulation, there also existed a range of spatial frequencies – namely very high and low frequencies – where participants could not estimate surface shape. Congruent with previous research, people were able to readily determine 3D shape using the information provided by specular reflections; however, performance was highly dependent upon surface and environment complexities. Image analysis reveals the specific conditions that subjects rely on to perform the task, explaining the pattern of errors.
Over the last decade a number of new technologies have been introduced to the area of spine care.... more Over the last decade a number of new technologies have been introduced to the area of spine care. Although this recent explosion of innovation has brought advances to patient care, it has also brought concerns regarding overuse, increasing costs, and safety. A value-based approach to assessing and purchasing new technology depends on a shift toward comparative effectiveness analysis, transparency in pricing and potential conflicts of interest, and an alignment of incentives and goals among purchasers, consumers, and payers. How to assess the effectiveness of new technology in patient care is an unresolved issue for any cost-effectiveness analysis, as models traditionally used to assess medical therapies (ie, quality-adjusted life years) may not be directly applicable to analysis of surgical intervention. Spine surgeons must be involved in multidisciplinary collaborative efforts to develop models of efficacy analysis and to direct outcomes-based research to appropriately evaluate the benefits of surgical interventions and new technologies.
The research described in the present article was designed to compare three types of image shadin... more The research described in the present article was designed to compare three types of image shading: one generated with a Lambertian BRDF and homogeneous illumination such that image intensity was determined entirely by local surface orientation irrespective of position; one that was textured with a linear intensity gradient, such that image intensity was determined entirely by local surface position irrespective of orientation; and another that was generated with a Lambertian BRDF and inhomogeneous illumination such that image intensity was influenced by both position and orientation. A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation. The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity. This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.
Intentional deception, as is common in the performance of magic tricks, can provide valuable insi... more Intentional deception, as is common in the performance of magic tricks, can provide valuable insight into the mechanisms of perception and action. Much of the recent investigations into this form of deception revolve around the attention of the observer. Here, we present experiments designed to investigate the contributions of the performer to the act of deception. An experienced magician and a naïve novice performed a classic sleight known as the French Drop. Video recordings of the performance were used to measure the quality of the deception-e.g., if a non-magician observer could discriminate instances where the sleight was performed (a deceptive performance) from those where it was not (a veridical performace). During the performance we recorded the trajectory of the hands and measured muscle activity via EMG to help understand the biomechanical mechanisms of this deception. We show that expertise plays a major role in the quality of the deception and that there are significant variations in the motion and muscular behaviors between successful and unsuccessful performances. Smooth, minimal movements with an exaggerated faux-transfer of muscular tension were characteristic of better deception. This finding is consistent with anecdotal reports and the magic performance literature.
Gustav Fechner is widely respected as a founding father of experimental psychology and psychophys... more Gustav Fechner is widely respected as a founding father of experimental psychology and psychophysics but fewer know of his interests and work in empirical aesthetics. In the later 1800s, toward the end of his career, Fechner performed experiments to empirically evaluate the beauty of rectangles, hypothesizing that the preferred shape would closely match that of the so-called 'golden rectangle'. His findings confirmed his suspicions, but in the intervening decades there has been significant evidence pointing away from that finding. Regardless of the results of this one study, Fechner ushered in the notion of using a metric to evaluate beauty in a psychophysical way. In this paper, we recreate the experiment using more naturalistic stimuli. We evaluate subjects' preferences against models that use various types of object complexity as metrics. Our findings that subjects prefer either very simple or very complex objects runs contrary to the hypothesized results, but are systematic none the less. We conclude that there are likely to be useful measures of aesthetic preference but they are likely to be complicated by the difficulty in defining some of their constituent parts.
Graphical information, such as illustrations, graphs, and diagrams, are an essential complement t... more Graphical information, such as illustrations, graphs, and diagrams, are an essential complement to text for conveying knowledge about the world. Although graphics can be communicated well via the visual modality, conveying this information via touch has proven to be challenging. The lack of easily comprehensible tactile graphics poses a problem for the blind. In this paper, we advance a hypothesis for the limited effectiveness of tactile graphics. The hypothesis contends that conventional graphics that rely upon embossings on two-dimensional surfaces do not allow the deployment of tactile exploratory procedures that are crucial for assessing global shape. Besides potentially accounting for some of the shortcomings of current approaches, this hypothesis also serves a prescriptive purpose by suggesting a different strategy for conveying graphical information via touch, one based on cutouts. We describe experiments demonstrating the greater effectiveness of this approach for conveying shape and identity information. These results hold the potential for creating more comprehensible tactile drawings for the visually impaired while also providing insights into shape estimation processes in the tactile modality.
It is well known that motion facilitates the visual perception of solid object shape, particularl... more It is well known that motion facilitates the visual perception of solid object shape, particularly when surface texture or other identifiable features (e.g., corners) are present. Conventional models of structure-from-motion require the presence of texture or identifiable object features in order to recover 3-D structure. Is the facilitation in 3-D shape perception similar in magnitude when surface texture is absent? On any given trial in the current experiments, participants were presented with a single randomly-selected solid object (bell pepper or randomly-shaped "glaven") for 12 seconds and were required to indicate which of 12 (for bell peppers) or 8 (for glavens) simultaneously visible objects possessed the same shape. The initial single object's shape was defined either by boundary contours alone (i.e., presented as a silhouette), specular highlights alone, specular highlights combined with boundary contours, or texture. In addition, there was a haptic condition...
Thesis (Ph. D.)--Ohio State University, 1997. Includes bibliographical references (leaves 90-95).... more Thesis (Ph. D.)--Ohio State University, 1997. Includes bibliographical references (leaves 90-95). Advisor: James T. Todd, Dept. of Psychology.
Is it possible for humans to navigate in the natural environment wherein the path taken between v... more Is it possible for humans to navigate in the natural environment wherein the path taken between various destinations is 'optimal' in some way? In the domain of optimization this challenge is traditionally framed as the "Traveling Salesman Problem" (TSP). What strategies and ecological considerations are plausible for human navigation? When given a two-dimensional map-like presentation of the destinations, participants solve this optimization exceptionally well (only 2-3% longer than optimum)^1, 2^. In the following experiments we investigate the effect of effort and its environmental affordance on navigation decisions when humans solve the TSP in the natural environment. Fifteen locations were marked on two outdoor landscapes with flat and varied terrains respectively. Performance in the flat-field condition was excellent (∼6% error) and was worse but still quite good in the variable-terrain condition (∼20% error), suggesting participants do not globally pre-plan r...
Humans are generally remarkably good at inferring 3D shape from distorted patterns of reflections... more Humans are generally remarkably good at inferring 3D shape from distorted patterns of reflections on mirror-like objects (Fleming et al, 2004). However, there are conditions in which shape perception fails (complex planar reliefs under certain illuminations; Faisman and Langer, 2013). A good theory of shape perception should predict failures as well as successes of shape perception, so here we sought to map out systematically the conditions under which subjects fail to estimate shape from specular reflections and to understand why. To do this, we parametrically varied the spatial complexity (spatial frequency content) of both 3D relief and illumination, and measured under which conditions subjects could and could not infer shape. Specifically, we simulated surface reliefs with varying spatial frequency content and rendered them as perfect mirrors under spherical harmonic light probes with varying frequency content. Participants viewed the mirror-like surfaces and performed a depth-discrimination task. On each trial, the participants’ task was to indicate which of two locations on the surface—selected randomly from a range of relative depth differences on the object’s surface—was higher in depth. We mapped out performance as a function of both the relief and the lighting parameters. Results show that while participants were accurate within a given range for each manipulation, there also existed a range of spatial frequencies – namely very high and low frequencies – where participants could not estimate surface shape. Congruent with previous research, people were able to readily determine 3D shape using the information provided by specular reflections; however, performance was highly dependent upon surface and environment complexities. Image analysis reveals the specific conditions that subjects rely on to perform the task, explaining the pattern of errors.
Over the last decade a number of new technologies have been introduced to the area of spine care.... more Over the last decade a number of new technologies have been introduced to the area of spine care. Although this recent explosion of innovation has brought advances to patient care, it has also brought concerns regarding overuse, increasing costs, and safety. A value-based approach to assessing and purchasing new technology depends on a shift toward comparative effectiveness analysis, transparency in pricing and potential conflicts of interest, and an alignment of incentives and goals among purchasers, consumers, and payers. How to assess the effectiveness of new technology in patient care is an unresolved issue for any cost-effectiveness analysis, as models traditionally used to assess medical therapies (ie, quality-adjusted life years) may not be directly applicable to analysis of surgical intervention. Spine surgeons must be involved in multidisciplinary collaborative efforts to develop models of efficacy analysis and to direct outcomes-based research to appropriately evaluate the benefits of surgical interventions and new technologies.
The research described in the present article was designed to compare three types of image shadin... more The research described in the present article was designed to compare three types of image shading: one generated with a Lambertian BRDF and homogeneous illumination such that image intensity was determined entirely by local surface orientation irrespective of position; one that was textured with a linear intensity gradient, such that image intensity was determined entirely by local surface position irrespective of orientation; and another that was generated with a Lambertian BRDF and inhomogeneous illumination such that image intensity was influenced by both position and orientation. A gauge figure adjustment task was used to measure observers' perceptions of local surface orientation on the depicted surfaces, and the probe points included 60 pairs of regions that both had the same orientation. The results show clearly that observers' perceptions of these three types of stimuli were remarkably similar, and that probe regions with similar apparent orientations could have large differences in image intensity. This latter finding is incompatible with any process for computing shape from shading that assumes any plausible reflectance function combined with any possible homogeneous illumination.
Intentional deception, as is common in the performance of magic tricks, can provide valuable insi... more Intentional deception, as is common in the performance of magic tricks, can provide valuable insight into the mechanisms of perception and action. Much of the recent investigations into this form of deception revolve around the attention of the observer. Here, we present experiments designed to investigate the contributions of the performer to the act of deception. An experienced magician and a naïve novice performed a classic sleight known as the French Drop. Video recordings of the performance were used to measure the quality of the deception-e.g., if a non-magician observer could discriminate instances where the sleight was performed (a deceptive performance) from those where it was not (a veridical performace). During the performance we recorded the trajectory of the hands and measured muscle activity via EMG to help understand the biomechanical mechanisms of this deception. We show that expertise plays a major role in the quality of the deception and that there are significant variations in the motion and muscular behaviors between successful and unsuccessful performances. Smooth, minimal movements with an exaggerated faux-transfer of muscular tension were characteristic of better deception. This finding is consistent with anecdotal reports and the magic performance literature.
Gustav Fechner is widely respected as a founding father of experimental psychology and psychophys... more Gustav Fechner is widely respected as a founding father of experimental psychology and psychophysics but fewer know of his interests and work in empirical aesthetics. In the later 1800s, toward the end of his career, Fechner performed experiments to empirically evaluate the beauty of rectangles, hypothesizing that the preferred shape would closely match that of the so-called 'golden rectangle'. His findings confirmed his suspicions, but in the intervening decades there has been significant evidence pointing away from that finding. Regardless of the results of this one study, Fechner ushered in the notion of using a metric to evaluate beauty in a psychophysical way. In this paper, we recreate the experiment using more naturalistic stimuli. We evaluate subjects' preferences against models that use various types of object complexity as metrics. Our findings that subjects prefer either very simple or very complex objects runs contrary to the hypothesized results, but are systematic none the less. We conclude that there are likely to be useful measures of aesthetic preference but they are likely to be complicated by the difficulty in defining some of their constituent parts.
Graphical information, such as illustrations, graphs, and diagrams, are an essential complement t... more Graphical information, such as illustrations, graphs, and diagrams, are an essential complement to text for conveying knowledge about the world. Although graphics can be communicated well via the visual modality, conveying this information via touch has proven to be challenging. The lack of easily comprehensible tactile graphics poses a problem for the blind. In this paper, we advance a hypothesis for the limited effectiveness of tactile graphics. The hypothesis contends that conventional graphics that rely upon embossings on two-dimensional surfaces do not allow the deployment of tactile exploratory procedures that are crucial for assessing global shape. Besides potentially accounting for some of the shortcomings of current approaches, this hypothesis also serves a prescriptive purpose by suggesting a different strategy for conveying graphical information via touch, one based on cutouts. We describe experiments demonstrating the greater effectiveness of this approach for conveying shape and identity information. These results hold the potential for creating more comprehensible tactile drawings for the visually impaired while also providing insights into shape estimation processes in the tactile modality.
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