GUIDED VISUAL SEARCH IS A LEFT-HEMISPHERE PROCESS IN SPLIT-BRAIN PATIENTS

Abstract— Previous research has shown that split-brain (callosotomy) patients search through visual displays twice as fast as normal observers when items are divided evenly between visual hemifields, as though each disconnected hemisphere possessed its own attentional scanning system (Luck, Hillyard, Mangun, & Gazzaniga, 1989, 1994) Results from 3 split-brain patients in the present study indicate that the ability to limit search to a relevant subset of the visual display is lateralized to the left cerebral hemisphere. This ability to perform guided search was not shown in the right hemisphere, even when the search time in that hemisphere was superior to search time in the left Furthermore, guided search was observed for both hemifields in normal control observers. These findings suggest that, as with higher cognitive processes such as language, strategic visuospatial attentional processes are preferentially lateralized to the left cerebral hemisphere. The findings also imply that the callosum mediates guided search in the right hemisphere of normal subjects     

GROUPING BY PROXIMITY AND MULTISTABILITY IN DOT LATTICES:

Abstract— 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 organisations, 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     

Globalization or indigenization: New alignments between knowledge and culture

The pace, shape and meaning of development are cultural phenomena—fundamentally driven by the meanings people ascribe to their action, to the symbols they aspire to, and by the wider values contexts within which they are acting. However, people participating within the development process continuously confront a tension between the assertion of the cultural meanings of the local known social world and the assertion of the meanings of an idealized largely unknown social world that stretches beyond immediate experience, and that is particularly represented in commodity symbols and media images. Tension is therefore between indigenization or globalization. The product, greater valence of indigenization or globalization, results from the alternative ways in which tension between the two domains is resolved. In the modern social world access to knowledge, as well as the impact of knowledge embodied within technological artifacts, are key drivers in both the level of participation in development and the level of colonization of indigenized meanings by globalized frameworks of understanding. The current paper therefore focuses on the role of knowledge within the interactions between globalization and indigenization. The paper demonstrates that the general trend of development during the last half of the twentieth century has driven cultural change towards more globalized meanings and dependencies. The dynamics of technological access and change are centrally implicated. However, new opportunities are opening up at both local indigenized levels and within modernizing sectors, and the essence of these opportunities lies in capturing a cultural advantage. At the indigenous society level, a focus on capitalizing on indigenous technical knowledge can have enormous payoffs in terms of economic development outcomes. Meanwhile, a focus on linking local with modernizing sectors through bridging technologies and knowledge across indigenous and global cultures allows indigenous cultures to share in the economic benefits of modernization. And finally, a new wave of change is emerging in the modernized sector itself, opening up quite new opportunities for “small players”—whether they be small firms or small countries. The opportunities are set within change in the global orders of technology and science over the last five to ten years. What matters is the ability of these small players to be highly responsive, to capture knowledge flows through both technical and social capabilities of their people; in other words, global advantage follows from capture of local cultural strength. Stephen Hill is foundation director for the Center for Research Policy, located at the University of Wollongong, and established as a special research center of the Australian Research Council. More recently, he was appointed Regional Director of UNESCO for South East Asia and the Pacific. Professor Hill will assume his new appointment in June, 1995.     

Auditory temporal perception deficits in the reading-impaired: A critical review of the evidence

We assess evidence and arguments brought forward by Tallal (e.g., 1980) and by the target paper (Farmer & Klein, 1995) for a general deficit in auditory temporal perception as the source of phonological deficits in impaired readers. We argue that (1) errors in temporal order judgment of both syllables and tones reflect difficulty in identifying similar (and so readily confusable) stimuli rapidly, not in judging their temporal order; (2) difficulty in identifying similar syllables or tones rapidly stem from independent deficits in speech and nonspeech discriminative capacity, not from a general deficit in rate of auditory perception; and (3) the results of dichotic experiments and studies of aphasics purporting to demonstrate left-hemisphere specialization for nonspeech auditory temporal perception are inconclusive. The paper supports its arguments with data from a recent control study. We conclude that, on the available evidence, the phonological deficit of impaired readers cannot be traced to any co-occurring nonspeech deficits so far observed and is phonetic in origin, but that its full nature, origin, and extent remain to be determined.     

Brief report: Effects of informational feedback on aluminum can recycling

The impact of informational feedback on the depositing of aluminum cans in recycling receptacles at a medium-sized university was investigated. Informational signs were placed over 20-recycling receptacles in three academic buildings. Each informational sign was placed at eye level, with the number of aluminum cans deposited for recycling during the previous week displayed in red digits. A 65% increase in the number of aluminum cans deposited in recycling receptacles with the informational signs was observed. Furthermore, removal of the informational signs was observed to reliably decrease the number of aluminum cans deposited. These results are discussed in the context of employing feedback to increase environmental protection behaviors.     

Non-heart-beating organ donation: a reply to Campbell and Weber.

In the preceding commentary, Campbell and Weber raise two valid and important issues concerning non-heart-beating organ donation (NHBOD). First, because the procedure links withdrawal of life support and the potential for subsequent organ donation, the desire for organs may create a situation in which care of the dying individual has relatively less importance and the dying may receive suboptimal care. Second, even if concerns about care of the dying were dealt with adequately, there will not be enough non-heart-beating donors to significantly decrease the organ shortage that exists, making the procedure not worth the risk. We agree that attention to the important details of caring for the dying are, and must be, the primary concern of all health care workers caring for those individuals. Ensuring the patients' comfort, dignity, and autonomy, and providing for family and social support are the mainstays of this care. All policies for NHBOD should clearly support and mandate these concepts. Regarding the second concern, we agree that NHBOD is currently rare; however, evidence is increasing that this type of donation has great potential. Continued growth of the practice in this country will depend largely on public acceptance, which we believe will be directly influenced by whether the public perceives that care of the dying is not compromised by this procedure.     

An historical preface to engineering ethics

This article attempts to distinguish between science and technology, on the one hand, and engineering, on the other, offering a brief introduction to engineering values and engineering ethics. The method is (roughly) a philosophical examination of history. Engineering turns out to be a relatively recent enterprise, barely three hundred years old, to have distinctive commitments both technical and moral, and to have changed a good deal both technically and morally during that period. What motivates the paper is the belief that a too-easy equation of engineering with technology tends to obscure the special contribution of engineers to technology and to their own professional standards and so, to obscure as well both the origin and content of engineering ethics.     

Five points and a lament about Range and Cotton's "Reports of assent and permission in research with children: illustrations and suggestions

This comment responds to an article by Range and Cotton (1995) on reporting of parental permission and child assent procedures in published articles for 4 psychology journals. Issue is taken with the assumptions, methodology, interpretations, and implications of listing researchers in the Range and Cotton article. There is no evidence researchers failed in their ethical obligations or that children were put at risk. Reporting permission/assent in publications is not an ethical requirement. Listing researchers as "failing" to do something not part of an ethical code is lamentable. Too many unfortunate implications and problems can be derived from Range and Cotton's analysis and conclusions.