Object-based selection operating on a spatial representation made salient by dimensional segmentation mechanisms: a re-investigation of Egly and Homa (1984)

Three experiments re-investigated selective attention in the ‘ring-cueing’ paradigm of Egly and Homa (J Exp Psychol: Human Percept Perform 10:778–793, 1984). Observers were cued to attend to one of three concentric rings of radius 1°, 2°, or 3°, and their signal detection accuracy for cued and uncued rings was measured. Experiment 1, which used a central color cue to indicate a like-colored ring, replicated ring-cueing effects along the lines of Egly and Homa. Experiments 2 and 3 examined whether these effects were produced by observers exploiting secondary-depth cues possibly inherent in the display layout. With color cues, the availability of secondary-depth information had no influence on the ring-cueing effects. However, making the rings monochrome and using central size cues significantly reduced the ring-cueing effects when the depth information was disrupted. The results suggest that selection was object-based, operating on a spatial ‘grouped-array’ representation of the cued ring made salient by color- or depth-based segmentation mechanisms.

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Closure of salient regions determines search for a collinear target configuration

Grouping operations offer an effective mechanism by which to structure complex visual scenes. Among the various principles that support element integration, closure may be regarded as a main factor in shape extraction. In five experiments, we investigated the impact of grouping by closure on search for target configurations made up of collinearly arranged corner junctions. Systematic variations in the configuration of distractor elements were explored to investigate how the figural information of distractors interferes with target detection. The results showed no search interference for distractor configurations that were open forms. By contrast, distractors making up closed forms reduced the efficiency of search performance, indicating closure as a major contributor to form detection in multielement configurations. In conclusion, the effects reported may be considered to arise from mechanisms of unit formation that support the rapid extraction of salient regions to guide search.     

Cross-trial priming of element positions in visual pop-out search is dependent on stimulus arrangement

Two experiments examined cross-trial positional priming (V. Maljkovic & K. Nakayama, 1994, 1996, 2000) in visual pop-out search. Experiment 1 used regularly arranged target and distractor displays, as in previous studies. Reaction times were expedited when the target appeared at a previous target location (facilitation relative to neutral baseline) and slowed when the target appeared at a previous distractor location (inhibition). In contrast to facilitation, inhibition emerged only after extended practice. Experiment 2 revealed reduced facilitatory and no inhibitory priming when the elements' spatial arrangement was made irregular, indicating that positional--in particular, inhibitory--priming critically depends on the configuration of the display elements across sequences of trials. These results are discussed with respect to the role of the context for cross-trial priming in visual pop-out search.     

Critical Afrikaner Intellectuals and Apartheid, 1943–1958

Apartheid dominated the political thinking of two generations of Afrikaner intellectuals from its first conceptualizations in the early 1940s to its disintegration as an ideology during the 1980s. Western Cape politicians, academics, journalists and church leaders were the main contributors to the Sauer Report, which was the greatest influence on the apartheid plank of the National Party's 1948 platform. Although apartheid as a policy did not clinch the NP victory, it won steady support in the course of the 1950s. The article discusses the work of four Afrikaner critics of apartheid as it was conceptualized and implemented in the first decade of NP rule. The most striking observations were those of the ambivalent figure of the poet and essayist N.P. van Wyk Louw, who has remained an important moral voice in the Afrikaner political tradition. André du Toit's Die Sondes van die Vaders (1983) built on some key arguments of Louw in arguing for the abandonment of apartheid as a way of securing Afrikaner survival.     

Die moderne Tierpfychologie

Ohne Zusammenfassung     

Symptom perception in childhood asthma: the role of anxiety and asthma severity.

This study tested the relationship of anxiety and asthma severity to symptom perception. Eighty-six children diagnosed with mild or moderate asthma had symptom perception and pulmonary function measured throughout methacholine challenge (to induce bronchoconstriction). Higher trait anxiety was associated with heightened symptom perception (controlling for pulmonary function) at baseline. Greater asthma severity was associated with blunted symptom perception (controlling for pulmonary function) at the end of methacholine challenge and with a slower rate of increase in symptom perception across methacholine challenge. These results suggest that anxiety plays a role when children's symptoms are mild, whereas medical variables such as severity play a role in perception of changes in asthma symptomatology as bronchoconstriction worsens.     

Kooperatives Lernen auf der Grundlage komplementären Vorwissens: ein Experiment und eine Simulationsstudie

Summary. Knowledge acquisition in collaborative problem solving is mainly realized by two activities: (1) when participants mutually impart their knowledge and (2) when they elaborate their knowledge together. Both activities are favoured by differences in the participants' prior knowledge. To support this thesis, an experimental study and a cognitive simulation are described. In the study, pairs of students were systematically taught complementary knowledge about qualitative resp. quantitative aspects of classical mechanics. During the subsequent collaborative problem solving the students successfully exchanged information about their complementary knowledge. Students who had been taught knowledge about qualitative aspects of physics gained more from their partners than students who had been taught knowledge about quantitative aspects. A cognitive model simulates problem solving and learning under the conditions set up in the study. In a simulation study based on the cognitive model it was possible to reconstruct the main results of the experimental study. Finally, the role of dialogue analysis and external representations are discussed and conclusions for the design of computer systems supporting collaborative problem solving are drawn. Zusammenfassung. Wissenserwerb bei der Kooperation vollzieht sich vor allem durch zwei Aktivitäten: (1) gegenseitige Wissensvermittlung und (2) gemeinsame Elaboration des Wissens. Für beides ist unterschiedliches Vorwissen der Beteiligten eine günstige Voraussetzung. Um diese These zu unterstützen, wird im vorliegenden Artikel eine experimentelle Studie dargestellt, in der Paaren von Schülerinnen systematisch komplementäres Vorwissen über qualitative bzw. quantitative Aspekte der klassischen Mechanik vermittelt wurde. Beim anschließenden kooperativen Problemlösen vermittelten die Schülerinnen sich gegenseitig erfolgreich Teile ihres Wissens. Schülerinnen, die zuvor Wissen über qualitative Aspekte der Physik erworben hatten, lernten dabei mehr von ihren Partnerinnen als Schülerinnen, die zuvor Wissen über quantitative Aspekte erworben hatten. Ein nachfolgend implementiertes kognitives Modell simuliert kooperatives Lernen und Problemlösen unter den Bedingungen der Studie und ist in der Lage, die zentralen Befunde der Studie zu rekonstruieren. In der Diskussion wird auf die Rolle des Dialogverhaltens und der Nutzung externer Repräsentationen für das kooperative Lernen und Problemlösen eingegangen. Abschließend werden Schlußfolgerungen für die Gestaltung von Computersystemen zur Unterstützung kooperativen Lernens und Problemlösens gezogen.     

Das ABC der farbigen Außenarchitektur

Ohne Zusammenfassung