Methods Used in My Research
Eye-Tracking
The Eye-Mind Link: Ongoing cognitive processes influence when and where we move our eyes during reading.
In an eye-tracking reading paradigm, participants read text on a computer screen while an infra-red light ray is directed at the eye. The light is reflected in the cornea and processed by a camera. Changes in reflection position and timing in relation to the presented stimuli are then recorded and measures such as fixation time and position can be extracted.
SR Research
Computational Modeling
Computational models can be used to simulate the lower-level (e.g., oculomotor, perceptual) and higher-level (e.g., visual word recognition, lexical access, post-lexical integration) processes that guide eye-movements during reading.
The E-Z Reader Model of Eye-Movement Control (Reichle et al., 1998) accounts for these processes, and postulates that words are identified serially (i.e., one at a time) during reading.
The E-Z Reader Model of Eye-Movement Control Reichle & Sheridan (2015)
Co-Registration of Eye-Movements and EEG
Degno & Liversedge (2020)
Eye-movements and event-related potentials (ERPs) can be simultaneously recorded (i.e., co-registered) to capitalize on the strengths of each method: the spatial precision of eye-tracking and the temporal precision of ERP.
In a co-registration experiment, rather than time-locking potentials to events (like in the classic ERP technique), potentials are time-locked to fixations and fixation related potentials (FRPs) can be examined.
Eye-movements are a problem for classic ERP studies because eye-movements produce artifacts that can obscure the presence of cognitive effects. Therefore, ERP studies and text stimuli are presented to the same location of the visual field using techniques such as the rapid serial presentation technique (RSVP) to prevent eye-movements. However, information on when and where our eyes move is an important factor for understanding reading. Unlike classic ERP studies, eye-movements are recorded during the co-registration of the eye-tracking and EEG technique, so artifacts from eye-movements can then be controlled.
In a tDCS paradigm, a weak electric current (1-2mA) is induced between two electrodes applied to the scalp while participants perform a task (e.g., reading passages).
Neuroexcitability is increased by applying anodal (positive) stimulation, and decreased by applying cathodal (negative) stimulation. Task performance (e.g., eye-movements, response times, comprehension accuracy) can then be assessed and compared between active and sham stimulation conditions.
Transcranial Direct Current Stimulation (tDCS)
Khan et al. (2020)