Abstract
It is under debate whether attention during smooth pursuit is centered right on the pursuit target or allocated preferentially ahead of it. Attentional deployment was previously probed using a secondary task on top of the execution of smooth pursuit, which might have altered attention allocation and led to inconsistent findings. We measured frequency-tagged steady-state visual invoked potentials (SSVEP) to measure attention allocation in the absence of any secondary probing task. Twelve observers pursued a moving dot while stimuli flickering at different frequencies were presented simultaneously at two locations ahead or behind the pursuit target. We observed a significant increase in EEG power (9.1%, Cohen's dz = 0.90) at the flicker frequency of the stimulus in front of the pursuit target, compared to that at the frequency of the stimulus behind. When testing many different locations in a second experiment (N = 12), we found that the enhancement was detectable up to about 1.5º ahead during pursuit (9.0%, Cohen's dz = 0.89), but vanished at 3.5º. In a control condition using attentional cueing during fixation, we did observe an enhanced SSVEP response to stimuli at this eccentricity, indicating that the focus of attention during pursuit is narrower than allowed for by the resolution of the attentional system. Overall, we showed that attention is allocated closely ahead of the pursuit target during smooth pursuit. EEG frequency tagging seems to be a powerful technique allowing investigating attention/perception implicitly when an overt task would be disruptive.
Meeting abstract presented at VSS 2017