Steady-state Visually Evoked Potentials: Improving Experimental Design and Identifying Sources of Variability

The original experiments presented in this manuscript began with the objective of utilizing steady-state visually evoked potentials (SSVEPs) as a tool for the study of visual attention and of attention disorders. The early outcomes of these experiments were not successful in reproducing effects that were reported to be quite robust by the relevant literature. This failure to replicate prior results precluded further interpretation of the data and launched a reexamination of the experimental design. Efforts to improve the application of SSVEPs specifically to the study of attention also led to a questioning of the assumptions about the properties of SSVEPs and to a thorough exploration into their sources of variability. This manuscript describes the development of precise methods for generating SSVEPs, presents the results of experiments investigating poorly understood SSVEP characteristics, and reveals sources of variability that can hinder SSVEP research. The outcomes of this project demonstrate that subtle stimulus parameters such as contrast and duty cycle can considerably impact SSVEP data. The culmination of this endeavor is a multimodal imaging study illustrating the relationship between evoked potentials across a range of frequencies as well as the distinctions between responses to periodic and aperiodic stimuli.