The role of selective attention for object integration

Nowack, Leonie (2022): The role of selective attention for object integration. Dissertation, LMU München: Graduate School of Systemic Neurosciences (GSN)

Abstract

Our brain has developed mechanisms, which structure and organize the complex visual input that we constantly perceive during everyday life. For instance, a given visual scene typically contains multiple sources of information that need to be structured and organized into meaningful perceptual units for higher-order capacity-limited processing. One mechanism that achieves an integration of the fragmented image parts into coherent whole objects is perceptual grouping. The organization of the visual environment by means of perceptual grouping appears to be achieved in a fairly effortless manner. However, whether such mechanisms of object integration operate automatically, or whether they depend on the engagement of attention is a matter of intense debate. The current dissertation aimed to investigate the role of attention in object completion in three different projects that combined methods from basic research with a clinical, neuropsychological, and neuroscientific perspective. The first project tested grouping of Kanizsa figures in both the impaired and the preserved hemifields of neuropsychological patients suffering from a hemifield-specific failure in selective attention. Results revealed that attention is only captured by salient groupings when it is not currently engaged elsewhere, thus showing that attention is indeed an integral part of object integration processes. The second project combined a behavioral task with eye gaze and pupil size measurements to elucidate the involvement of attention in perception and object integration. Results of two experiments indicated that perceptual grouping scales with the allocation of attention, provided that at least residual attentional resources are available to trigger the representation of a complete (target) object. Finally, by using transcranial magnetic stimulation (TMS), we investigated the causal contribution of the right parietal cortex for successful object integration in healthy participants. We found that this brain region seems to mediate the processing of object groupings. It up- and down regulates the deployment of attention to spatial regions where to-be-grouped items require attentional resources for object completion. Taken together, this dissertation provides new evidence that at least some residual amounts of attention are required to bind fragmentary parts into coherent whole percepts in the first place, such that these integrated objects can in turn capture attention.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Themengebiete: 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie
• Fakultäten: Graduate School of Systemic Neurosciences (GSN)
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 1. Juli 2022
• 1. Bericht­erstatter:in: Conci, Markus