Milar towards the multiplicative noise masking process referred to as “bubbles” (e.
Milar towards the multiplicative noise masking procedure called “bubbles” (e.g. visual masking with randomly distributed Gaussian apertures; Gosselin CP-533536 free acid Schyns, 200), which has been applied successfully in numerous domains such as face perception and in a few of our preceding perform investigating biological motion perception (Thurman et al 200; Thurman Grossman, 20). Masking was applied to VCV video clips in the MaskedAV situation. For any offered clip, we 1st downsampled the clip to 2020 pixels, and from this lowresolution clip we chosen a 305 pixel region covering the mouth and part from the lower jaw of the speaker. The mean worth of your pixels within this area was subtracted and also a 305 mouthregion masker was applied as follows: a random noise image was generated from a uniform distribution for every single frame. (2) A Gaussian blur was applied to the random image sequence in the temporal domain (sigma Author Manuscript Author Manuscript Author Manuscript Author ManuscriptAtten Percept Psychophys. Author manuscript; available in PMC 207 February 0.Venezia et al.Page2. frames) and within the spatial domain (sigma four pixels) to make correlated spatiotemporal noise patterns. These had been in fact lowpass filters with frequency cutoffs of 0.75 cyclesface and 4.5 Hz, respectively. Cutoff frequency was determined based on the sigma in the Gaussian filter within the frequency domain (or the point at which the filter get was 0.6065 of maximum). The extremely low cutoff in the spatial domain made a “shutterlike” effect when the noise masker was added for the mouth area from the stimulus i.e the masker tended to obscure significant portions from the mouth area when it was opaque (Figure ). (three) The blurred image sequence was scaled to a range of [0 ] plus the resultant values were raised to the fourth power (i.e a power transform) to make essentially a map of alpha transparency values that have been mainly opaque (e.g. close to 0), but with clusters of regions with high transparency (e.g. values close to ). Especially, “alpha transparency” refers to the degree to which the background image is allowed to show by means of the masker ( entirely unmasked, 0 fully masked, with a continuous scale between and 0). (four) The alpha map was scaled to a maximum of 0.five (a noise level discovered in pilot testing to perform properly with audiovisual speech stimuli). (five) The processed 305 image sequence was multiplied for the 305 mouth region in the original video separately in each and every RGB color frame. (six) The contrast variance and mean intensity of the masked mouth region was adjusted to match the original video sequence. (7) The completely processed sequence was upsampled to 48080 pixels for display. In the resultant video, a masker with spatiotemporally correlated alpha transparency values covered the mouth. Particularly, the mouth was (at the very least partially) visible in particular frames in the video, but not in other frames PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/23701633 (Figure ). Maskers have been generated in real time and at random for each trial, such that no masker had precisely the same pattern of transparent pixels. The essential manipulation was masking of McGurk stimuli, where the logic with the masking procedure is as follows: when transparent components with the masker reveal essential visual attributes (i.e on the mouth during articulation), the McGurk effect is going to be obtained; alternatively, when important visual characteristics are blocked by the masker, the McGurk impact is going to be blocked. The set of visual options that contribute reliably to the impact may be estimated from t.
