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Julia Thompson, David Crewther; The attentional strobe: auditory manipulation of visual conscious awareness. Journal of Vision 2015;15(12):1251. doi: 10.1167/15.12.1251.
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© ARVO (1962-2015); The Authors (2016-present)
The discrete nature of visual attention has become a recent topic of interest. Using techniques of psychophysics and magnetoencephalography (MEG), we searched for indications of the presence of an "attentional strobe" and the degree to which it could be manipulated using auditory stimulation. Participants undertook visual change detection tasks. The “rapid” task was used to detect the abrupt change in contrast of one of approximately 15 coloured dots in a standard gap paradigm. The “gradual” task required the detection, in a similar array of dots, of one dot that was slowly fluctuating in contrast. Two auditory conditions were employed – one with 10Hz tone bursts (3.3kHz, duration 5ms, sound level 52dB) and the other without auditory stimulation. For the rapid task, the threshold for least visible step in contrast was measured, while for the gradual task, the least frequency of sinusoidal fluctuation in one of the dots that could be detected was measured. Threshold contrast decreased with 10Hz stimulation for the rapid task while threshold frequency increased for the gradual task with 10Hz stimulation. A significant Task (rapid, gradual) x Auditory (10Hz, no sound) interaction (F(1,20)=7.6, p=.012) was found. MEG analysis of theta band power difference over posterior parietal sensors showed opposite effects of auditory stimulation for the rapid and gradual tasks at latencies of approximately 150ms. The psychophysical results (better detection of rapid changes, worse detection of gradual changes) are consistent with auditory stimulation producing an increase in attentional strobe rate. The fluctuations in MEG theta power indicate that manipulation of attentional modulation level may also need to be addressed.
Meeting abstract presented at VSS 2015
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