Abstract
A growing body of research has associated brain oscillations with the cognitive process of selective attention, as well as visual perception. Modulation of alpha frequency band (8-14Hz) has been related to changes in perception and attention with an inverse correlation between alpha amplitude and perceptual ability. To date the association between alpha and target detection has been shown in numerous studies but using only near-threshold stimuli. Here we attempt to study the extent to which visual entrainment at alpha and non-alpha frequencies will affect attention in a more complex, higher level target detection task. In the current experiment subjects took part in a visual search task where they were instructed to find a target among a set of distractors. The visual search display was preceded by a stimulus which either flickered in alpha (10Hz), non-alpha (random flicker sequence with an average of 10 Hz) frequency or was a static control. Given that alpha entrainment has been shown to enhance endogenous alpha levels, we predicted alpha entrainment to increase reaction time (RT) for target detection. On the other hand, as non-alpha stimulation should prevent alpha synchronisation, we predicted shorter RTs in this condition. The results reveal that non-alpha flicker stimulation resulted in significantly faster target detection in the visual search task compared to the control condition. Alpha entrainment gave rise to marginally slower RTs than non-alpha, while at the same time marginally faster than the control. The pattern of results suggests that entrainment allows for quicker responses than in the static control condition. These results are in line with research showing that inhibition of alpha is associated with better attentional and perceptual performance.
Meeting abstract presented at VSS 2015