Exploring Attentional Neural Differences During an Oddball Paradigm: An SSVEP Study

Abstract

Attention wields a significant influence on visual processing and its impact on neural activity seems to become progressively greater as information cascades through the visual stream. This study explores how attention modulates visual object processing. Recording neural activity with electroencephalography (EEG) using steady state visually evoked potentials (SSVEP) elicited by images of faces and objects we aim to investigate high-level visual processing.Participants varying in self-reported symptoms of Attentional Deficit Hyperactivity Disorder (ADHD) took part in two SSVEP experiments, one for faces and the other for objects, where attention was modulated. The SSVEP response was elicited by fast periodic visual stimulation, with a rapid display at a rate of 6 cycles per second (6 Hz; base frequency) were 5 cycles consisted of the same face or object and every 5th cycle a different face or object appeared. This oddball stimulus introduced during a stream of base level stimuli differs only on high-level dimensions and is therefore well suitable to high-level visual activity.The measured effect of this oddball stimulus, or the oddball power, is used to estimate the influence of attention on high-level visual processes. Attention was modulated by having participants either attend to the high-level stimuli or a fixation point (a point with colour) superimposed on the stimuli so the effects of attention could be estimated. Participants were asked to pick the faces/colours or objects they saw during the trial.Results indicate that the oddball power for complex stimuli, faces and objects, is positively correlated with ADHD scores.