Interhemisphärischer Transfer visueller Zweifachwahlen bei kommissurotomierten Tauben

Zusammenfassung Die funktionelle Bedeutung kommissuraler Systeme für den visuellen interhemisphärischen Informationsaustausch wurde bei 71 Tauben an monokular gelernten Zweifachwahlen geprüft (instrumentale Konditionierung nach Skinner). 1 Farb- und 4 Form-Diskriminationen (2 oben-unten- und 2 links-rechts-symmetrische Spiegelbildpaare) wurden verwendet. Bei 21 Tauben war die Decussatio supraoptica (DSO) stereotaktisch durchtrennt worden, bei 20 waren die Commissura tectalis (CT) und die Commissura posterior (CP) durchschnitten. Bei 11 Tauben waren alle 3 Verbindungen unterbrochen. Das Ausmaß der Läsionen wurde durch histologische Kontrolle verifiziert. Der interhemisphärische Transfer war nach DSO-Durchtrennung bei der Farb- und den oben-unten-symmetrischen Formzweifachwahlen stark vermindert. Der Transfer sämtlicher Zweifachwahlen war nach CT+CP-Durchtrennung nicht signifikant verschieden von dem der Kontrolltiere. Es wurde erstmals gezeigt, daß mindestens ein Teil der DSO-Fasern bei Vögeln visuelle Information von einer Hirnhälfte zur andern übermittelt.

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Interhemispheric transfer of two-choice discrimination in commissurotomized pigeons

Summary The role of avian commissural systems in interhemispheric transfer of monocularly learned visual discriminations was investigated in an instrumental conditioning situation (Skinner). Color and pattern (up-down and left-right mirror-images) were used as stimuli. Stereotaxic lesions were placed in the supraoptic decussation of 21 pigeons, in the tectal and posterior commissures of 20 pigeons. In 11 animals all three connections were interrupted. All lesions were histologically verified. After section of the supraoptic decussation interhemispheric transfer was severely impaired for one color and two up-down mirror-image discriminations. No significant impairment in transfer for color, up-down and left-right mirror-image discriminations followed section of the tectal and posterior commissures. These data demonstrate that at least part of the supraoptic decussation is involved in interhemispheric transfer of visual information.

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Mit Unterstützung des Schweizerischen Nationalfonds für wissenschaftliche Forschung, Kredit Nr. 4806 und 3.133.69. Ein Teil dieser Arbeit wurde im Oktober 1969 der European Brain and Behaviour Society in Marseille vorgetragen.

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Hern Prof. Dr. K. Akert danke ich für die Überlassung des Themas und für die wertvolle Unterstützung während meiner Untersuchungen recht herzlich.Herrn Prof. Dr. E. Hadorn danke ich als meinem verehrten Lehrer.Großer Dank gebührt aber vor allem Herrn Dr. M. Cuénod, der mir stets mit Rat und Tat zur Seite stand.Für ihre technische Mithilfe sei Frau M. Müller, Frl. L. Decoppet, Frl. R. Emch, Frl. I. Kost, Herrn A. Fäh, Herrn A. Fidéler und Herrn M. Plattner, sowie Frl. M. Zwicky, die die Reinschrift besorgte, bestens gedankt.     

Situation models,mental simulations,and abstract concepts in discourse comprehension

This article sets out to examine the role of symbolic and sensorimotor representations in discourse comprehension. It starts out with a review of the literature on situation models, showing how mental representations are constrained by linguistic and situational factors. These ideas are then extended to more explicitly include sensorimotor representations. Following Zwaan and Madden (2005), the author argues that sensorimotor and symbolic representations mutually constrain each other in discourse comprehension. These ideas are then developed further to propose two roles for abstract concepts in discourse comprehension. It is argued that they serve as pointers in memory, used (1) cataphorically to integrate upcoming information into a sensorimotor simulation, or (2) anaphorically integrate previously presented information into a sensorimotor simulation. In either case, the sensorimotor representation is a specific instantiation of the abstract concept.     

Social Identity and Social Exchange: Identification, Support, and Withdrawal From the Job

Integrating insights from the social exchange perspective and the social identity perspective, we propose that evaluations of support received from the organization and its representatives and organizational identification interact to predict withdrawal from the job. The relationship of support with withdrawal is proposed to be weaker the more strongly employees identify with the organization. This prediction was confirmed in 2 samples focusing on different operationalizations of support and withdrawal. Study 1 explored the interaction between organizational support and organizational identification in predicting turnover intention; Study 2 investigated the link between supervisor support and organizational identification and absenteeism. The present study thus yields evidence that may lay the groundwork for further integration of social exchange and social identity analyses of organizational behavior.     

Length of Group Membership, Assumed Similarity, and Opinion Certainty: The Dividend for Veteran Members

Newcomer and veteran fraternity members indicated their own attitudinal position on each of 10 issues and then estimated the positions of either prospective or full in-group members or they received no opportunity to project. All subjects then rated their certainty about their own position on each issue. As expected. both newcomers and veterans assumed greater attitudinal similarity to in-group members than to prospective members. Moreover, projection onto in-group members only increased the opinion certainty of veteran members. Their certainty correlated with the percentage of their friends who were in-group members. Newcomers' certainty increased only after projection onto the lower status recruits. Membership tenure and social identity are discussed in relation to attitudinal projection and the goals of social comparison.     

Perceptual simulation in developing language comprehension

We tested an embodied account of language proposing that comprehenders create perceptual simulations of the events they hear and read about. In Experiment 1, children (ages 7–13 years) performed a picture verification task. Each picture was preceded by a prerecorded spoken sentence describing an entity whose shape or orientation matched or mismatched the depicted object. Responses were faster for matching pictures, suggesting that participants had formed perceptual-like situation models of the sentences. The advantage for matching pictures did not increase with age. Experiment 2 extended these findings to the domain of written language. Participants (ages 7–10 years) of high and low word reading ability verified pictures after reading sentences aloud. The results suggest that even when reading is effortful, children construct a perceptual simulation of the described events. We propose that perceptual simulation plays a more central role in developing language comprehension than was previously thought.     

Metaimagining and Embodied Conceptions of Spacetime

Though we live in a 4-dimensional universe, our minds and bodies are not particularly good at perceiving and depicting 4 dimensions. This study contributes to our understanding of collaboration with abstract concepts by examining particular activities where bodily and experiential understandings may conflict with the conceptual domain. Specifically, upper secondary physics classrooms studying Einstein’s general theory of relativity are taken as a setting to identify the representational practices and conceptual challenges that arise when learners attempt to make meaning with, and express conflicting notions of, space and time. To unpack these challenges, we draw on the concept of imagination and on theoretical perspectives that treat imagining as a social activity. We also present the concept of metaimagining to characterize layered processes in which learners attend to and manage shifts between their own imaginative activities. This concept is illustrated through a detailed analysis of an extended conversation between 2 upper secondary physics students working with general relativity and spacetime. The students perform a diverse set of imaginative activities that are strongly tied to communicative, cognitive, and bodily action. We also show how the unique domain of general relativity presents particular challenges to student meaning making of abstract concepts which in turn prompt metaimagining. Based on our analysis, we offer recommendations to improve instructional practices in general relativity and argue for the consideration of imagining as a transdisciplinary competency in math and science education.     

Threshold estimation in two-alternative forced-choice (2AFC) tasks: The Spearman-Kärber method

The Spearman-Kärber method can be used to estimate the threshold value or difference limen in two-alternative forced-choice tasks. This method yields a simple estimator for the difference limen and its standard error, so that both can be calculated with a pocket calculator. In contrast to previous estimators, the present approach does not require any assumptions about the shape of the true underlying psychometric function. The performance of this new nonparametric estimator is compared with the standard technique of probit analysis. The Spearman-Kärber method appears to be a valuable addition to the toolbox of psychophysical methods, because it is most accurate for estimating the mean (i.e., absolute and difference thresholds) and dispersion of the psychometric function, although it is not optimal for estimating percentile-based parameters of this function.