In the audiovisual group (group AV), a spatially congruent visual stimulation was presented simultaneously to the sound.
The role of visual inputs in spatial auditory adaptation has been clearly demonstrated using modified vision [26] and is also present in our study as the simultaneous presentation of a spatially congruent visual stimulus leads to the greater amount of improvement.
In the second group, auditory stimuli were accompanied in half of the cases by an azimuth spatially congruent visual LED (Group AV).
By presenting a temporally and spatially (in azimuth) congruent visual cue, subjects present a significant larger improvement in monaural localization, a result in line with the rule that multisensory perceptual learning depends on the congruency of the two sensory stimuli [41], [44].
In healthy individuals, as used in the case of our study, it seems that a couple of minutes of congruent visual and tactile stimulation is sufficient to up-regulate the ipsilateral somatosensory processing.
The second experiment, which included incongruent stimuli, included four conditions: visual-only (V), auditory-only (A), congruent auditory-visual (A = V), and incongruent auditory-visual (A≠V).
Interpretations of previous adult data (Pilling, 2009; Van Wassenhove et al., 2005) have rested on the effect of congruence-dependency, with congruent visual cues suggested to allow a prediction of the upcoming auditory signal, such that the degree of latency shortening reflects the difference between expected and perceived events.
Four different response conditions were compared in a between-subjects design: (1) unimanual, (2) bimanual, (3) congruent visual field/response hand, and (4) confounded response hand/target lexicality response.
Analysis of MEG responses using synthetic aperture magnetometry (SAM) revealed that congruent stimuli evoked larger 2-10 Hz activity in the left auditory cortex within the first 250 ms after stimulus onset, and smaller 2-16 Hz activity in bilateral visual cortices between 250 and 500 ms. These results indicate that congruent visual input can modify cortical activity in the left auditory cortex.
Experimental results on a dataset of 10 full-body actions show that our system achieves state-of-the-art classification performance without requiring the manual segmentation of training samples, and that congruent visual representations can be retrieved from recognized speech in the absence of visual stimuli.
Furthermore, early auditory evoked potentials (at 50 ms) in response to speech are modulated by congruent visual stimuli [91], [92].
