My PhD project investigates how the brain handles visual information that lost its relevance after it was encoded into working memory.
In addition to behavioral parameters, I record the electroencephalogram in order to gain a deeper understanding of the underlying neurophysiological processes of attentional selection within working memory. We are especially interested in neuronal oscillations in the alpha (8-14 Hz; associated with inhibition) and theta frequency range (4-7 Hz; associated with cognitive control).
Every second of your life, you are surrounded by a vast amount of visual information. In order to function effectively it is necessary to selectively deploy attention towards information that is currently relevant. However, what might or might not be relevant is not always known at the time information is encountered in the environment. Thus, in certain situations we are required to selectively re-orient attention between memory representations of information.
The project started in August 2018 and is supervised by Daniel Schneider.
First of all, we asked the question, how attention is shifted between representations within working memory. Therefore, we conducted an experiment with a retro-active cue. The cue indicated either a subset of the memorized information as further on task relevant (selective cue) or gave no information at all (neutral cue). Only selective cues required a shift of attention towards a subset of working memory representations. By comparing the EEG data following both cue types, we could show that the withdrawal of attention from irrelevant information was associated with inhibitory processes as reflected in posterior alpha power modulations. However, attentional shifts towards relevant information was not accompanied by enhanced processing of relevant information as indicated by an absence of respective alpha power modulations. This demonstrates that attention with working memory is shifted by inhibitory processes.
In a second experiment I investigated together with my PhD colleague Bianca Zickerick how the storage of information within working memory is affected by interruptions. Furthermore, we were interested in the flexibility of attention allocation between a working memory task and different types of interruption tasks. This way we could show that re-focusing attention on task-relevant information after completing an interruption task is accompanied by modulations in posterior alpha power. Importantly, these modulations differ depending on the cognitive demands of the interruption task. Cognitive demands were also reflected in modulations in frontal theta power. The stronger the cognitive demands of the interruption task are, the stronger the impairment of the re-focusing on task relevant information afterwards. However, there is hope: efficient inhibitory processes, as reflected in posterior alpha power, after finishing the interruption task decrease the detrimental impact of interruptions.
In both above described experiments I analyzed attentional selection processes between separate objects. In future work, I will focus on the complexity of working memory representations. Especially I am going to do research about attentional selection processes between features of complex objects. So, stay tuned for more information on this next project.