Two-dimensional filtering,oriented line detectors,and figural aspects as determinants of visual illusions

Quantitative data of Müller-Lyer illusions from the literature were analyzed according to three different models. All three models predict the illusion effect, although with different magnitude and different parameter dependency. First, a filter model describing a certain amount of blurring of the retinal picture seems partly responsible for the observed illusion. With reasonable estimation of the filter constants, however, a sufficient magnitude of illusion cannot be obtained. A second model of oriented line or bar receptors is even less effective in explaining the observed length illusions. A third model, consisting of a size-constancy operator triggered by depth cues, may predict effects larger than actually observed. It is concluded that figural aspects such as depth-inducing cues are mainly responsible for the illusion effects observed in Müller-Lyer figures.     

Illusion in a three-dimensional Hering figure in relation to viewing distance

Two groups of 34 Ss each judged the amount of illusion in a three-dimensional Hering figure at three viewing distances (9, 18, and 36 ft). The horizontal bars could be located in the foremost frontal plane of the three-dimensional display or could be recessed within it. Group C-F began at the close distance and Group F-C at the furthest distance. Amount of illusion increased with viewing distance and was greater with the bars recessed within the display. At the furthest distance, but not at the other distances, amount of illusion was greater for Group F-C. The results confirm predictions from Gregory’s theory of primary constancy scaling but are also interpretable in terms of local effects at the intersections of parallel bars and background lines.     

The Religious Ethics of Labor

While unionization rates have steadily declined in the United States, there has been a renewal of grassroots labor organizing—in many cases connected in some way with religious communities. Attending to such organizing efforts holds the potential to deepen religious‐ethical reflection on questions of labor, and these religious‐ethical reflections hold the potential to enrich on‐the‐ground organizing efforts. These opportunities have largely been overlooked. On the one hand, while scholars have recently explored connections between religious ideas and economic ideas, they have often neglected questions of labor. On the other hand, labor studies scholars have often ignored the role of religion, although this is beginning to change. In this introduction we limn the resources available for religious‐ethical reflection on questions of labor and we propose a direction that the field could take, bringing together engagement with religious traditions and attunement to grassroots organizing.