Geestmann, Mareen

[["dc.contributor.advisorcorporation","Georg-August-Universität Göttingen"],["dc.contributor.author","Berndt, Mareen"],["dc.date.accessioned","2019-03-14T10:12:22Z"],["dc.date.available","2019-03-14T10:12:22Z"],["dc.date.issued","2016"],["dc.description.abstract","n metacontrast masking the visibility of the first stimulus (the target) is reduced due to the appearance of the second stimulus (the mask). Two masking functions mainly occur: \"Type A\", when visibility is increasing with increasing SOA, and \"Type B\", where visibility is high in short and long SOAs and dropped to a minimum in between. In five studies it systematically investigated which influence different experimental parameters have on metacontrast masking functions. The longer the mask duration becomes in relation to the target duration, the more the minimum of the masking function shifts towards shorter SOAs, and the more Type-A-like (monotonically increasing) the function becomes. In the center and in the periphery masking is stronger in small stimuli than in large stimuli, and the SOA of the strongest masking occurred at the shortest SOA in both stimulus sizes. Masking functions are identical for predictable and unpredictable stimulus presentation locations. Apparent motion is better detected in long SOAs than in short SOAs. Furthermore, inter-individual differences were found, which were used to get insights in the mechanisms involved in metacontrast masking. Some participants show a Type A masking function and mostly report to perceive apparent movements in the sequence of both stimuli, mainly in long SOAs. Others show a Type B masking function and mostly report to perceive negative afterimages in the shape of the target inside the mask, mainly in short SOAs. Type A and Type B observers do differ in their top-down processing, but not in their bottom-up processing of metacontrast stimuli. Two processes could be revealed, which may be involved. According to the Integration-Segregation-Theory the perception of two stimuli being segregated, enabling apparent moving images, are associated to the segregation process. The percept of simultaneous, conjoint image of two physically succeeding stimuli are associated to the integration process. As Process 1 is strongly associated with a Type A masking function, which in turn goes along with a percept of motion, it may correspond to the segregation process. As Process 2 is strongly associated with a Type B masking function, which in turn goes along with a percept of negative afterimages inside of the mask stimulus, it may correspond to the integration process. It is assumed that these two processes are involved in the conscious perception of the target stimulus in metacontrast masking."],["dc.description.abstract","In der Metakontrastmaskierung wird die Sichtbarkeit des ersten Stimulus (Target) durch das Auftreten eines zweiten Stimulus (Maske) reduziert. Zwei Maskierungsfunktionen (MF) treten hauptsächlich auf: Typ A, wenn die Sichtbarkeit mit ansteigender SOA zumimmt, und Typ-B, wenn die Sichtbarkeit in kurzer und langer SOA hoch ist und auf ein Minimum in mittlerer SOA abfällt. In fünf Studien wurde systematisch untersucht welchen Einfluss experimentelle Parameter auf das Auftreten der MF haben. Je länger die Maske im Verhältnis zum Target präsentiert wird, desto weiter verschiebt sich das Minimum der MF hin zu kürzerer SOA und desto mehr ähnelt sie einer Typ-A-MF (monoton ansteigend). Die Maskierung ist in kleinen Stimuli stärker als in großen Stimuli, sowohl im Zentrum als auch in der Peripherie. Bei beiden Stimulusgrößen findet bei der kürzesten SOA die stärkste Maskierung statt. MF unterscheiden sich nicht, wenn sich die Vorhersagbarkeit der Präsentationsorte der Stimuli unterscheidet. Scheinbewegungen werden in langen SOAs eher wahrgenommen als in kurzen SOAs. Darüber hinaus wurden inter-individuelle Unterschiede gefunden, die Einblicke in die Mechanismen erlauben, die in der Metakontrastmaskierung beteiligt sind. Einige Versuchspersonen zeigen eine Typ-A-MF und berichten Scheinbewegungen in der Abfolge der Stimuli wahrzunehmen, hauptsächlich in langen SOAs. Andere zeigen eine Typ-B-MF und berichten negative Nachbilder in Form des Tagets im Inneren der Maske wahrzunehmen, hauptsächlich in kurzen SOAs. Typ-A- und Typ-B-Versuchspersonen unterscheiden sich in ihrer Top-Down-Verarbeitung der Stimuli, nicht aber in ihrer Bottom-Up-Verarbeitung. Zwei Prozesse stellten sich heraus, die in der Verarbeitung der Metakontraststimuli beteiligt sein könnten. Nach der Integrations-Segregations-Theorie steht die getrennte (segregierte) Wahrnehmung zweier Stimuli, die Scheinbewegungen ermöglicht, mit dem Segregationsprozess in Zusammenhang. Dagegen steht die gleichzeitige (integrierte) Wahrnehmung zweier nacheinander folgender Stimuli mit dem Integrationsprozess in Zusammenhang. Da Prozess 1 stark mit einer Typ-A-MF verknüpft ist, einhergehend mit der Wahrnehmung von Scheinbewegungen, könnte dieser Prozess dem Segregationsprozess entsprechen. Da Prozess 2 stark mit einer Typ-B-MF verknüpft ist, einhergehend mit der Wahrnehmung negativer Nachbilder, könnte dieser Prozess dem Integrationsprozess entsprechen. Es wird angenommen, dass diese beiden Prozesse an der bewussten Wahrnehmung des Targets in der Metakontrastmaskierung beteiligt sind."],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/57675"],["dc.language.iso","en"],["dc.notes.status","Dissertation"],["dc.publisher","Niedersächsische Staats- und Universitätsbibliothek Göttingen"],["dc.publisher.place","Göttingen"],["dc.title","Inter-Individual Differences as Instrument to Investigate the Mechanisms in Metacontrast Masking"],["dc.type","thesis"],["dc.type.internalPublication","unknown"],["dc.type.subtype","dissertation"],["dspace.entity.type","Publication"]]

[["dc.contributor.author","Berndt, Mareen"],["dc.contributor.author","Mattler, U."],["dc.contributor.author","Albrecht, T."],["dc.date.accessioned","2019-03-14T10:20:10Z"],["dc.date.available","2019-03-14T10:20:10Z"],["dc.date.issued","2013"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/57676"],["dc.language.iso","de"],["dc.notes.status","final"],["dc.relation.conference","46. Herbsttreffen Experimentelle Kognitionspsychologie (HExKoP)"],["dc.relation.date","2013-11-22"],["dc.relation.eventlocation","Göttingen"],["dc.title","Einfluss der Präsentationsdauern von Zielreiz und Maske auf das Auftreten interindividueller Unterschiede bei der Metakontastmaskierung"],["dc.type","lecture"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.contributor.author","Berndt, Mareen"],["dc.contributor.author","Mattler, U."],["dc.contributor.author","Albrecht, T."],["dc.date.accessioned","2019-03-14T10:27:22Z"],["dc.date.available","2019-03-14T10:27:22Z"],["dc.date.issued","2016"],["dc.description.abstract","By analyzing individual data, Albrecht and colleagues found qualitative inter-individual differences in studies with metacontrast masking, appearing in phenomenological perception as well as in discrimination performance (Albrecht & Mattler, 2012a, 2012b). They used the metacontrast paradigm, where two stimuli are presented sequentially and the visibility of the first stimulus (target) is reduced due to the appearance of the second stimulus (mask). The visibility is a function of the stimulus-onset-asynchrony (SOA). Participants differ in that respect whether the visibility of the target increases with increasing SOA (type A) or whether it is U-shaped (type B). These differences in the objective performance correlate with differences in the phenomenological experience (apparent motion vs. negative afterimage) as well as in the response criteria. A first ERP study also indicated differences in the sensory neural processing. This study aims to clarify whether these neural differences reflect either a different intentional attention on experimental stimuli (top-down) or a different bottom-up processing. For this, participants attended two sessions. In the first session metacontrast stimuli were presented but they had to focus the fixation point and detect an occasionally appearing color change (condition “without attention”). The experimental design in the second session was identical to the first, but participants had to focus their attention on the metacontrast stimuli and to discriminate the shape of the target (condition “with attention”). We expect to find group differences between type A and type B participants in the condition “with attention” and replicate data of the first ERP study. Finding these differences in the condition “without attention” as well would indicate a bottom-up processing; no differences would indicate a different top-down processing."],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/57677"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.conference","58. Conference of Experimental Psychologists (TeaP)"],["dc.relation.date","2016"],["dc.relation.eventlocation","Heidelberg"],["dc.title","The Role of Attention in Processing of Visual Stimuli in Metacontrast Masking"],["dc.type","lecture"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]