Poster Session D, Monday, March 25, 8:00 – 10:00 am, Pacific Concourse
Rhythmic attentional sampling of visual and auditory objects is reflected in theta-modulated neural activity
Michael Plöchl1, Ian Fiebelkorn2, Sabine Kastner2, Jonas Obleser1; 1University of Luebeck, Germany, 2Princeton University, NJ
Visual attention samples single objects rhythmically at ~8Hz. When two objects are attended simultaneously, these objects are sequentially sampled at ~4Hz and in counter-phase. However, whether similar attentional rhythms also exist in other modalities is still a matter of debate. Therefore, we adapted and extended an established paradigm to investigate potential visual and auditory attentional rhythms and their possible interactions on both a behavioral (detection performance, N=33) and a neural level (EEG, N=18). After an attention reset towards one of two presented objects, our participants’ detection performance alternated between target locations at a rate of ~4Hz during unimodal visual attention and at ~8Hz during unimodal auditory attention, possibly indicating that auditory stimulation was perceived as a single object with two different target locations. At occipital EEG electrodes ipsi- and contralateral to the visual attention reset event theta activity (4-8Hz) oscillated in counter-phase, which was also reflected in a corresponding modulation of alpha power. In both modalities we observed phase opposition between hit and miss trials at frontal channels: Detection performance was predicted by the 4Hz (visual) and 2-4Hz (auditory) phase of the alpha power envelope. Auditory hits and misses additionally displayed phase opposition at 8Hz. During bimodal attention the above-mentioned effects were reduced and did not become significant. Overall, we present behavioral and neural evidence for attentional theta rhythms in both the visual and auditory modality. The reduction of effects during bimodal attention furthermore suggests that these rhythms may interact on a supramodal level.
Topic Area: ATTENTION: Multisensory