Two kinds of adaptation in the constancy of visual direction and their different effects on the perception of shape and visual direction

Adaptation in the constancy of visual direction can be obtained under two radically different conditions, called eye-movement adaptation and field adaptation. Adaptation resulting from these conditions and from a “normal” condition was measured with a newly developed estimation test. Eye-movement adaptation was found to cause an alteration of compensatory eye movements. It apparently consists of a changed evaluation of eye movements, as demonstrated by two different pointing tests. A form test where the shape of a large oblong is set to look square also confirmed this interpretation. After field adaptation, a pointing test did not register a change, but an adaptation effect could be measured with a forward direction test. This test and a square test where no eye movements were permitted proved to be specific to field adaptation; they measured no effect after eye-movementadaptation. The normal adaptation condition Was apparently equivalent to the eye-movement adaptation condition. Its effect could be measured only with a pointing test. When we changed the normal adaptation condition so that frequent saccades were made during head turning, strong effects were measured with the two tests that were specific to field adaptation.     

Ursachen der gegenseitigen Verdeckung von taktil dargebotenen Buchstaben: Unterbrechung,Summation oder Verzögerung?

Zusammenfassung Für die Erklärung der Verdeckung von Reizen in verschiedenen Sinnesmodalitäten mit einfacher Struktur wurden in der Literature bisher im wesentlichen zwei verschiedene Erklärungskonzepte diskutiert: Die Summationshypotheses behauptet, daß die Eindrücke von schnell aufeinanderfolgenden Reizen sich zu einer Gesamtrepräsentation überlagern, aus der die Einzelreize erschwert herauszuanalysieren sind, die Unterbrechungshypothese dagegen nimmt an, daß die Verdeckung auf eine Störung der Verarbeitung des einen Reizes durch die kurzzeitig folgende Darbietung eines weiteren Reizes zurückgeht. Zur Erklärung der gegenseitigen Verdeckung von taktil dargebotenen Buchstaben sind beide Hypothesen ungeeignet, weil sie die unterschiedliche Beeinträchtigung von Form- und Positionserkennung der Buchstaben nicht erfassen können. Deshalb wurde eine neue Hypothese aufgestellt: Die Repräsentation eines Reizes im sensorischen Register wird durch die Merkmalsanalyse des vorangegangenen Reizes kaum behindert, aber dessen Übertragung aus dem analysierenden System in das Kurzzeitgedächtnis eine bestimmte Zeit verzögert. Diese Verzögerungshypothese wurde mit einem Experiment überprüft, in dem 3 Vpn je etwa 12 Versuchsstunden lang die Erkennung von Buchstabenpaaren übten. Da die Diskrimination zwischen den Buchstaben bei taktiler Darbietung sehr viel schwieriger als bei visueller ist, wurden nur 5 Buchstaben im Experiment verwendet. Die Ergebnisse des Experiments werden durch ein mathematisches Modell beschrieben. Bezüglich der numerischen Werte der freien Parameter machen die 3 Hypothesen unterschiedliche Vorhersagen. Die Parameterschätzung ergab eine gute Übereinstimmung des Modells mit den Daten und zeigte eine Überlegenheit des Konzeptes Verzögerung für die Erklärung der gegenseitigen Verdeckung taktil dargebotener Buchstaben.

---

Sources of mutual masking of tactile presented letters: Interruption, summation or delay?

Summary Two different explanations of the masking phenomenon with simple structured stimuli have been discussed in the literature: The summation hypothesis and the interruption hypothesis. The summation hypothesis maintains that the images of quickly succeeding stimuli superimpose and build up one unified representation from which the single stimuli are difficult to analyse. In contrast the interruption hypothesis assumes that masking is caused by the successive stimulus disturbing the processing of its predecessor. Both hypotheses are unacceptable for an explanation of the mutual masking of tactile presented letters where a different impairment of form and position recognition is observed. Therefore a third hypothesis was tried: The processing of a preceding stimulus hardly affects the representation of the successive one in the sensory register. Rather the transfer from the analysing system to short-term memory is delayed by a certain time. This delay hypothesis was tested by an experiment in which three subjects practiced to recognize pairs of letters for a total of 12 sessions. Since discrimination between letters is much more difficult with tactile compared to visual presentation only five letters were used as stimuli. The results are described by a mathematical model. The three hypotheses predict discrepant numerical values for the free parameters. Parameter estimation revealed a close fit between the general model and the data and showed a superiority of the delay hypothesis as an explanation of mutual masking of tactile presented stimuli.

---

---

Für die wertvolle Beratung bei der Erstellung des endgültigen Textes danken wir besonders Herrn Professor Dr. K. F. Wender und Herr Dr. K. Nippert.     

Personal Contact with Refugees is Key to Welcoming Them: An Analysis of Politicians' and Citizens' Attitudes Towards Refugee Integration

Politicians are influential both in directing policies about refugees and in framing public discourse about them. However, unlike other host country residents, politicians' attitudes towards refugees and integration are remarkably understudied. We therefore examine similarities and differences between politicians' attitudes towards refugee integration and those held by citizens. Based on the stereotype content model, we expect that political ideology informs stereotypes about refugees, which subsequently shape attitudes towards refugee integration. Based on the Contact Hypothesis, we further argue that personal contact with refugees reduces negative stereotypes about them—in particular for those endorsing a right-wing ideology. We draw on data collected via two surveys with 905 politicians and 8013 citizens in the Netherlands to show that (1) unlike those with a left-wing orientation, residents (i.e., both politicians and citizens) with a right-wing orientation hold more negative stereotypes about refugees, which in turn relate to more negative attitudes towards refugee integration; (2) personal contact with refugees is associated with less negative stereotypes among residents; and (3) politicians, compared to citizens, report less negative stereotypes and more positive attitudes towards refugee integration. The practical implication of fostering residents' contact with refugees as well as the implications for future research are discussed.