Dr Ellen Seiss

Research Interests

My research interests include the cognitive and neural aspects of attention and response selection in healthy participants and patients with Parkinson’s disease. I use a combination of behavioural and neural imaging methods (EEG, ERP) to investigate the following questions:

1. Glucose effects on cognitive processes
   What is the impact of drinking sugary drinks on perception, response selection, performing tasks with low and high task demands, etc.. Together with Christopher Hope and Prof. Annette Sterr, we try to answer this question by systematically varying cognitive parameters that might be influenced by blood sugar levels. These levels are altered by giving participants drinks containing glucose or a placebo substance in experiments with double-blind designs.
2. Control processes in spatial attention
   Shifting attention in space is defined by two processes: the execution of the shift to the attended location and the modulation of sensory processing at the attended location. Both processes can be explored using ERP potentials. Using cueing paradigms, the main focus of my research is on how ERP potentials linked to shifts in spatial attention vary in response to task manipulations, e.g. change of task difficulty or modality (audition or vision) of the stimuli. Ongoing projects include the combination of the cueing paradigm with visual search tasks and an investigation of attention deficits in patients with Parkinson’s disease.
3. Masked priming
   Subliminally (no conscious perception) presented stimuli can influence our behaviour. One way of studying this phenomenon is by using masked priming paradigms. Here, a stimulus is immediately masked by a second stimulus and, therefore, cannot be consciously perceived. After a short interval, a second visible stimulus follows. The task of the participant is to respond to the second stimulus. This response is often influenced by the type of the first masked stimulus. This paradigm can be used to study several questions linked to subconscious processing of information.
4. Response selection deficits in Parkinson’s disease patients
   It is well established that Parkinson’s disease patients are less able to select and de-select response/movement alternatives is fast succession. This deficit can be seen when patients perform sequential tasks with many movement components, such as writing. Another way to investigate response selection deficits in Parkinson’s disease patients is conflict tasks, such as the Stroop, Simon and Eriksen flanker tasks. In all these tasks, participants respond to one stimulus feature while ignoring other stimulus/response features. Here, patients show increased interference effects. They have more problems ignoring irrelevant stimulus feature compared to controls. The focus of my previous and on-going research in this area is the possible cause of these increased interference effects.
5. Trial-and-error learning in Parkinson’s disease
   Probabilistic trial-and-error learning is altered in Parkinson’s disease patients. They process feedback given in these learning tasks differently. More specifically, Parkinson’s disease patients rely more on positive feedback (“carrot”) when on dopaminergic medication, and more on negative feedback (“stick”) when they are off medication. The modulation of trial-and-error learning by dopaminergic medication is likely to be linked to the reward system of the basal ganglia, a brain area affected in Parkinson’s disease (Frank, 2004, Science). My work will be investigating this phenomenon more in detail.

Research projects are currently available for topics 1, 2, and 5.

Please contact me [E.Seiss@surrey.ac.uk] if you are interested in a project or need further information.

Publications