The experiments reported herein probe the visual cortical mechanisms that control near–far percepts in response to two-dimensional stimuli. Figural contrast is found to be a principal factor for the emergence of percepts of near versus far in pictorial stimuli, especially when stimulus duration is brief. Pictorial factors such as interposition (Experiment 1) and partial occlusion Experiments 2 and 3) may cooperate, as generally predicted by cue combination models, or compete with contrast factors in the manner predicted by the FACADE model. (...) In particular, if the geometrical conŽ guration of an image favors activation of cortical bipole grouping cells, as at the top of a T-junction, then this advantage can cooperate with the contrast of the conŽ guration to facilitate a near–far percept at a lower contrast than at an X-junction. Varying the exposure duration of the stimuli shows that the more balanced bipole competition in the X-junction case takes longer exposure times to resolve than the bipole competition in the T-junction case (Experiment 3). (shrink)

Luminance and color are strong and self-sufficient cues to pictorial depth in visual scenes and images. The present study investigates the conditions Under which luminance or color either strengthens or overrides geometric depth cues. We investigated how luminance contrasts associated with color contrast interact with relative height in the visual field, partial occlusion, and interposition in determining the probability that a given figure is perceived as ‘‘nearer’’ than another. Latencies of ‘‘near’’ responses were analyzed to test for effects (...) of attentional selection. Figures in a pair were supported by luminance contrast or isoluminant color contrast and combined with one of the three geometric cues. The results of Experiment 1 show that luminance contrasts associated with hue, when it does not interact with other hues, produces the same effects as achromatic luminance contrasts: The probability of‘‘near’’ increases with luminance contrast while the latencies for ‘‘near’’ responses decrease. Partial occlusion is found to be a strong enough pictorial cue to support a weaker red luminance contrast. Interposition cues lose out against cues of spatial position and partial occlusion. The results of Experiment 2, with isoluminant displays of varying color contrast, reveal that red color contrast on a light background supported by any of the three geometric cues wins over green or white supported by any of the three geometric cues. On a dark background, red color contrast supported by the interposition cue loses out against green or white color contrast supported by partial occlusion. These findings reveal that color is not an independent depth cue, but is strongly influenced by luminance contrast and stimulus geometry. Systematically shorter response latencies for stronger ‘‘near’’ percepts demonstrate that selective visual attention reliably detects the most likely depth cue combination in a given configuration. (shrink)

It is common for visitors to have rich and varied experiences in the limited space of a classical Chinese garden. This leads to the sense that the garden’s scale is much larger than it really is. A main reason for this perceptual bias is the gardener’s manipulation of visual information. Most studies have discussed this phenomenon in terms of qualitative description with fragmented perspectives taken from static points, without considering ambient visual information or continuously changing observation points. A general question (...) arises, then, on why depth perception can vary from one observation point to another along a garden path. To better understand the spatial experience in classical Chinese gardens, this study focused on variations in perceived depth among different observation points and aimed to identify influential visual information through psychophysical experimentation. As stimuli for the experiment, panoramic photos of Liu garden were taken from three positions at Lvyin Pavilion. Considering the effects of pictorial visual cues on depth perception, the photos were processed to create 18 kinds of stimuli. Two tasks were presented to the participants. In Task 1, 71 participants were asked to rate the depth value of the garden using the magnitude estimation method in a cave automatic virtual environment. Statistical analysis of Task 1 revealed that depth values differed significantly among different viewpoints. In Task 2, participants were asked to compare 18 stimuli and 3D images presented on three connected monitors and to judge the depth of the garden using the adjustment method. The results of Task 2 again showed that depth values differed significantly among different viewpoints. In both tasks, ambient information significantly influenced depth perception. (shrink)

Two experiments were performed to explore the mechanisms of human 3D shape perception. In Experiment 1, the subjects’ performance in a shape constancy task in the presence of several cues (edges, binocular disparity, shading and texture) was tested. The results show that edges and binocular disparity, but not shading or texture, are important in 3D shape perception. Experiment 2 tested the effect of several simplicity constraints, such as symmetry and planarity on subjects’ performance in a shape constancy task. (...) The 3D shapes were represented by edges or vertices only. The results show that performance with or without binocular disparity is at chance level, unless the 3D shape is symmetric and/or its faces are planar. In both experiments, there was a correlation between the subjects’ performance with and without binocular disparity. Our study suggests that simplicity constraints, not depth cues, play the primary role in both monocular and binocular 3D shape perception. These results are consistent with our computational model of 3D shape recovery. (shrink)

Little is known about distance processing in patients with posterior brain damage. Although many investigators have claimed that distance estimates are normal or abnormal in some of these patients, many of these observations were made informally and the examiners often asked for relative, and not absolute, distance estimates. The present investigation served two purposes. First, we wanted to contrast the use of distance information in peripersonal space for perceptual report as opposed to visuomotor control in our visual form agnosic patient, (...) DF. Second, we wanted to see to what extent her abilities to process distance cues were dependent on binocular vision, in light of Milner et al.'s (1991) observations of preserved stereopsis in DF, and Dijkerman et al.'s (1996) and Marotta et al.'s (1997) observations that her visual guidance of grasping may be particularly dependent on binocular vision of the target. We hypothesized that DF's visuomotor responses would show normal sensitivity to target distance, while her perceptual estimates would not. In the first experiment, we required DF and two age- and sex-matched control subjects to reach out and grasp black cubes placed at varying distances, or to estimate the distance of the cubes from the hand starting position without making a reaching movement. In the second experiment, we required DF and two age-matched control subjects to point as rapidly and accurately as possible to small LED targets which differed in spatial location, under binocular and monocular conditions. The results showed that, relative to the control subjects, DF's grasping movements produced normal peak velocity-distance scaling-when she reached for blocks which varied in depth or pointed to LED targets which were presented at different distances in depth. In contrast, in the cube experiment, her verbal estimates of object distance were poorly scaled, although they improved slightly under the binocular conditions. The results are discussed in terms of current theories of processing streams in extrastriate visual cortex and the distinction between categorical and coordinate spatial processing. (shrink)

The concept of depth is central to Merleau-Ponty’s phenomenology and informed not only his philosophy of perception but also his thinking about psychology, art and politics. This article traces the ways the notion of depth appears in Merleau-Ponty’s thinking in these fields, contrasting it with Husserl’s own phenomenological investigations. The article starts with a comparison of the function of perception in Husserl’s phenomenology and then proceeds with an analysis of how the issue of depth reappears (...) in Merleau-Ponty’s phenomenology of perception, phenomenology of art and political philosophy. I argue that while Husserl’s approach to phenomenology led him to analyses of aesthetics stemming from works of art as random examples, and to non-participation in politics, Merleau-Ponty’s phenomenology leads to the opposite approach, inviting concrete criticism in art and active participation in politics. It is argued that Merleau-Ponty’s approach is more philosophically consistent. The choice of particular works of art, and the particular political engagements, can retrospectively clarify the transcendental phenomenological investigations themselves. (shrink)

We investigate how the selection of assurance topics and the format of their communication influence the credibility perception of sustainability report readers. This is important because misleading communication may discredit ethical sustainability assurance practices. Based on signaling theory and using an experimental approach, we are the first to examine false credibility signals in the context of sustainability assurance. We find that two variables related to sustainability assurance, reference explicitness and assurance depth, jointly influence the assurance signal and the (...) perceived credibility of a sustainability report. Our findings indicate that readers are not at risk of false signaling but can make incorrect interpretations of the assurance signal and might respond negatively to well-intentioned signals. The main implications of our findings are that firms should refrain from increasing reference explicitness and should select only the most material topics. Taken together, our results provide new insights on the unethical practice of false signaling and provide an example of an incorrect signal interpretation by readers. (shrink)

Speech perception under adverse conditions is a multistage process involving a dynamic interplay among acoustic, cognitive, and linguistic factors. Nevertheless, prior research has primarily focused on factors within this complex system in isolation. The primary goal of the present study was to examine the interaction between processing depth and the acoustic challenge of noise and its effect on processing effort during speech perception in noise. Two tasks were used to represent different depths of processing. The speech recognition (...) task involved repeating back a sentence after auditory presentation, while the tiredness judgment task entailed a subjective judgment of whether the speaker sounded tired. The secondary goal of the study was to investigate whether pupil response to alteration of dynamic pitch cues stems from difficult linguistic processing of speech content in noise or a perceptual novelty effect due to the unnatural pitch contours. Task-evoked peak pupil response from two groups of younger adult participants with typical hearing was measured in two experiments. Both tasks were implemented in both experiments, and stimuli were presented with background noise in Experiment 1 and without noise in Experiment 2. Increased peak pupil dilation was associated with deeper processing, particularly in the presence of background noise. Importantly, there is a non-additive interaction between noise and task, as demonstrated by the heightened peak pupil dilation to noise in the speech recognition task as compared to in the tiredness judgment task. Additionally, peak pupil dilation data suggest dynamic pitch alteration induced an increased perceptual novelty effect rather than reflecting effortful linguistic processing of the speech content in noise. These findings extend current theories of speech perception under adverse conditions by demonstrating that the level of processing effort expended by a listener is influenced by the interaction between acoustic challenges and depth of linguistic processing. The study also provides a foundation for future work to investigate the effects of this complex interaction in clinical populations who experience both hearing and cognitive challenges. (shrink)

This comprehensively updated and expanded revision of the successful second edition continues to provide detailed coverage of the ever-growing range of research topics in vision. In Part I, the treatment of visual physiology has been extensively revised with an updated account of retinal processing, a new section explaining the principles of spatial and temporal filtering which underlie discussions in later chapters, and an up-to-date account of the primate visual pathway. Part II contains four largely new chapters which cover recent psychophysical (...) evidence and computational model of early vision: edge detection, perceptual grouping, depth perception, and motion perception. The models discussed are extensively integrated with physiological evidence. All other chapters in Parts II, III, and IV have also been thoroughly updated. (shrink)