Divided attention and redundancy gain
When people divide their attention between two possible input stimuli, they react more rapidly when both stimuli are presented simultaneously than when just one is presented (ie, “redundancy gain effect”). Surprisingly, this phenomenon is especially large when the two redundant stimuli are presented to the two disconnected cerebral hemispheres of split-brain individuals. This project is concerned with teasing apart sensory versus motor causes of the redundancy gain effect.
Performance impairments in dual-task situations
When we try to do two tasks at the same time, our performance almost always suffers in at least one of the tasks. This project investigates how our cognitive processes are affected in such dual-task situations, in order to characterise precisely the reasons for these impairments.
Consciousness and the brain
Psychological and psychophysiological data have the potential to shed light on the age-old mind-body problem by elucidating the relationship between our brain states and our conscious awareness. I have recently reactivated an old interest in this topic and am now carrying out new studies.
Understanding reaction time
The goal of this project is to characterise the time course of the cognitive processes used when we carry out simple perceptual and decision-making tasks. For example, I would like to find out in which cases the different mental processes operate in strict sequence, with each finishing before the next begins, and in which cases they operate in parallel (at least partly at the same time). This issue is important on theoretical grounds (what are the temporal relationships among the mental processing carrying out distinct information processing aspects of a task?), methodological grounds (what does a reaction time measurement reflect?), and applied grounds (how can we maximise performance by capitalising on the brain's capacity to perform multiple operations in parallel?). To find out, I manipulate various determinants of task difficulty and study both behaviour (response time and accuracy) and psychophysiological responses (EEG, EMG, response force).
In all areas of my research, I look for ways to improve upon existing practices of data analysis. This has led to the development of some high specialised techniques for analysing reaction times, response choices, and EEG responses (often, with associated software), and to some general observations about the hypothesis testing scenario commonly used in psychology.
Miller, J. (2023). How many participants? How many trials? Maximizing the power of reaction time studies. Behavior Research Methods. Advance online publication. doi: 10.3758/s13428-023-02155-9
Miller, J. (2023). Outlier exclusion procedures for reaction time analysis: The cures are generally worse than the disease. Journal of Experimental Psychology: General. Advance online publication. doi: 10.1037/xge0001450
Janczyk, M., & Miller, J. (2023). Generalization of unpredictable action effect features: Large individual differences with little on-average effect. Quarterly Journal of Experimental Psychology. Advance online publication. doi: 10.1177/17470218231184996
Mittelstädt, V., Mackenzie, I. G., & Miller, J. (2022). Evidence of resource sharing in the Psychological Refractory Period (PRP) paradigm. Journal of Experimental Psychology: Human Perception & Performance, 48(11), 1279-1293. doi: 10.1037/xhp0001052
Winter, A., Dudschig, C., Miller, J., Ulrich, R., & Kaup, B. (2022). The action-sentence compatibility effect (ACE): Meta-analysis of a benchmark finding for embodiment. Acta Psychologica, 230, 103712. doi: 10.1016/j.actpsy.2022.103712