The opportunity an object presents for action is known as an ‘affordance’. A basic assumption in previous research is that images of objects, which do not afford physical action, elicit effects on attention and behavior comparable to that of real-world tangible objects. Using a flanker task, we compared interference effects between real graspable objects versus matched two-dimensional (2D) or three-dimensional (3D) images of the items. Compared to both 2D and 3D images, real objects slowed response times overall and elicited greater flanker interference effects. When the real objects were positioned out of reach, or behind a transparent barrier, the pattern of RTs and interference effects was comparable to 2D images. Graspable objects exert a more powerful influence on attention and manual responses than images due to the affordances they offer for manual interaction. These results raise questions about whether images are suitable proxies for real objects in psychological research.

There is mounting evidence that constraints from action can influence the early stages of object selection, even in the absence of any explicit preparation for action. Here, we examined whether action properties of images can influence visual search, and whether such effects were modulated by hand preference. Observers searched for an oddball target among three distractors. The search arrays consisted either of images of graspable ‘handles’ (‘action-related’ stimuli), or images that were otherwise identical to the handles but in which the semicircular fulcrum element was re-oriented so that the stimuli no longer looked like graspable objects (‘non-action-related’ stimuli). In Experiment 1, right-handed observers, who have been shown previously to prefer to use the right hand over the left for manual tasks, were faster to detect targets in action-related versus non-action-related arrays, and showed a response time (RT) advantage for rightward- versus leftward-oriented action-related handles. In Experiment 2, left-handed observers, who have been shown to use the left and right hands relatively equally in manual tasks, were also faster to detect targets in the action-related versus non-action-related arrays, but RTs were equally fast for rightward- and leftward-oriented handle targets. Together, or results suggest that action properties in images, and constraints for action imposed by preferences for manual interaction with objects, can influence attentional selection in the context of visual search.

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A major challenge in studying naturalistic vision lies in controlling stimulus and scene viewing time. This is especially the case for studies using real-world objects as stimuli (rather than computerized images) because real objects cannot be “onset” and “offset” in the same way that images can be. Since the late 1980s, one solution to this problem has been to have the observer wear electro-optic spectacles with computer-controlled liquid-crystal lenses that switch between transparent (“open”) and translucent (“closed”) states. Unfortunately, the commercially available glasses (PLATO Visual Occlusion Spectacles) command a high price tag, the hardware is fragile, and the glasses cannot be customized. This led us to explore how to manufacture liquid-crystal occlusion glasses in our own laboratory. Here, we share the products of our work by providing step-by-step instructions for researchers to design, build, operate, and test liquid-crystal glasses for use in experimental contexts. The glasses can be assembled with minimal technical knowledge using readily available components, and they can be customized for different populations and applications. The glasses are robust, and they can be produced at a fraction of the cost of commercial alternatives. Tests of reliability and temporal accuracy show that the performance of our laboratory prototype was comparable to that of the PLATO glasses. We discuss the results of our work with respect to implications for promoting rigor and reproducibility, potential use cases, comparisons with other liquid-crystal shutter glasses, and how users can find information regarding future updates and developments.

On a prétendu qu'en fondant l'État du Bundu (ca. 1698), Malik Sy s'inspirait consciemment du réformateur Nâsir al-Dîn, initiateur de jihâd en Mauritanie (la Shurbubba) et dans le nord-ouest du Sénégal (le mouvement tubenan) entre 1672-73 et 1677. Les sources concernant Malik Sy doivent être utilisées avec précaution, étant donné leur caractère presque exclusivement oral : aucune n'est contemporaine de Malik Sy. Dans ces conditions, un réexamen des matériaux ne confirme pas la thèse selon laquelle Malik Sy était le protégé de Nâsir al-Dïn. Il n'a pas participé aux jihâd de ce dernier, et on ne peut prouver qu'il ait mené son propre jihâd dans le futur Bundu. En outre, bien qu'ayant adopté le titre d'eliman, il n'en faisait pas, à la différence de Nâsir al-Dïn, l'équivalent légal d'amir al-mu'minin puisque le Bundu n'était pas gouverné selon les règles de la sharï'a. Plutôt qu'un réformateur, Malik Sy était un fonctionnaire clérical spécialisé dans la fabrication d'amulettes. Ceux qui veulent voir un lien entre Nâsir al-Dîn et les jihâd ultérieurs au Futa Jalon et au Futa Toro doivent chercher ailleurs.

Beginning with Latin America in the fifteenth century, this book, first published in 2005, is a social history of the experiences of African Muslims and their descendants throughout the Americas, including the Caribbean. The record under slavery is examined, as is the post-slavery period into the twentieth century. The experiences vary, arguably due to some extent to the Old World context. Muslim revolts in Brazil are also discussed, especially in 1835, by way of a nuanced analysis. The second part of the book looks at the emergence of Islam among the African-descended in the United States in the twentieth century, with successive chapters on Noble Drew Ali, Elijah Muhammad, and Malcolm X, with a view to explaining how orthodoxy arose from varied unorthodox roots.

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Songhay sources compiled in the seventeenth century portray the relationship between Gao, the political capital of the state, and Timbuktu, the religious and commercial centre, as abnormally important. The view is that Timbuktu was not only autonomous, but a source of important political influence over policy decisions at Gao. A consensus of contemporary scholars has embraced this depiction. In contrast, the present study argues that Timbuktu was not autonomous, but that Gao was sucessful in achieving its original objective in capturing the city: financial profit. In addition, the evidence is consistent in outlining the relatively negligible political influence of Timbuktu over Gao. The Timbuktu-centric chronicles are largely responsible for this distortion; it is therefore necessary to approach these sources with even greater caution. It is also desirable to re-examine the roles of other sahelian entrepots during the imperial Songhay period to determine more accurately their relative importance.