The Fixation Distance to the Stimulus Influences ERP Quality: An EEG and Eye Tracking N400 Study

Abstract

In a typical visual Event Related Potential (ERP) study, the stimulus is presented centrally on the screen. Normally an ERP response will be measured provided that the participant directs their gaze towards the stimulus. The aim of this study was to assess how the N400 component of an ERP was affected when the stimulus was presented in the foveal, parafoveal or peripheral vision of the participant’s visual field. Utilizing stimuli that have previously produced an N400 response to action incongruities, the same stimuli sequences were presented at 0°, 4°, 8° and 12° of visual angle from a fixation location. In addition to the EEG data, eye tracking data were recorded to act as a fixation control method and to allow for eye artifact detection. The results show a significant N400 effect in the right parieto-temporal electrodes within the 0° visual angle condition. For the other conditions, the N400 effect was reduced (4°) or not present (8° and 12°). Our results suggest that the disappearance of the N400 effect with eccentricity is due to the fixation distance to the stimulus. However, variables like attentional allocation could have also had an impact on the results. This study highlights the importance of presenting a stimulus within the foveal vision of the participant in order to maximize ERP effects related to higher order cognitive processes.

Semantic processing of actions at 9months is linked to language proficiency at 9 and 18months

“…A significant interaction between condition and time indicates validity for the hypothesis that the N400 component is only evident for the unexpected condition as a function of variance over time. The repeated measure ANOVA therefore featured the two factors condition (expected, unexpected) and time (17 samples at one sample per 12ms) -as suggested by Hoorman et al (1998), and further applied by Reid et al (2009) and Domínguez-Martínez, Parise, Strandvall and Reid (2015) in N400 research. We selected 17 samples at 12ms as this best reflected the difference between conditions.…”

Event-related potentials discriminate familiar and unusual goal outcomes in 5-month-olds and adults.

“…For instance, an increase in pupil dilation in response to the action outcomes presented with and without the action context would inform us about the role of the presented action context for infants action understanding ( Gredebäck & Melinder, 2010 ). Such combined methods are currently under development and, despite added complexities, stand to yield a number of advances in infancy research ( Domínguez-Martínez, Parise, Strandvall, & Reid, 2015 ; Wass, de Barbaro, & Clackson, 2015 ).…”

The Use of Eye Tracking to Discern the Threshold at Which Metopic Orbitofrontal Deformity Attracts Attention

“…A fixation, as the eye tracker follows a participant’s pupils, is defined as a point of minimal eye movement. Specifically, movement less than a circle with the radius of 0.75° of visual angle, which roughly corresponds to the high acuity area of the retina (fovea) (Salvucci and Goldberg, 2000; Tobii Technology AB, 2012; Dominguez-Martinez et al, 2015). The size of 1° of visual angle is standardized by the participant sitting the recommended distance from the eye tracker (65-68 cm) during calibration and the experiment, roughly 45 pixels or 11.25 mm (Tobii Technology AB, 2012).…”