If a word was not clearly understood they were instructed to guess the word. Otherwise they should report ‘I did not understand anything’. The answer was recorded by the experimenter. Any answer different from the presented stimulus was counted as false, no matter if the participant had indicated to not have understood anything or had reported a wrong word. When

the answer was given, the experimenter triggered the next trial which began with a fixation cross of one-second duration followed by the video stimulus. According to Ross et al. (2007) the gain in comprehension brought about by the visual information can be calculated by subtracting the performance in the auditory-alone condition from the performance in the audiovisual condition (AV-A). Gain AP24534 ic50 is maximal at -12 dB SNR for normal subjects and decreases with changes in SNR in both directions (Ross et al., 2007). Performance itself was

maximal at 0 dB SNR. Thus, we decided to group stimuli with an SNR around the maximal gain of integration (−8, −12 and −16 dB, henceforth Proteases inhibitor ‘inner’ stimuli) and stimuli with less expected gain (0, −4, −20 and −24 dB, henceforth ‘outer’ stimuli). For the first class of stimuli we expected large differences between both experimental groups with better performance for synesthesia subjects if they indeed have a more sensitive binding mechanism. For the latter class of stimuli, we expected no large differences between groups. The data were analysed with a two repeated-measures ANOVAs, medchemexpress one for separately calculated for inner and one for outer SNR stimuli, with the factors STIMULATION (auditory vs. audiovisual), SNR (inner respectively outer range stimuli; 3 respectively 4 levels) and GROUP (control

vs. synesthesia). In all three audiovisual congruent trial types, accuracy levels were at ceiling (synesthetes: 98.7% ± 4.2%, controls: 96.2% ± 5.5%) as is depicted in Figure 1. A t-test between groups did not show any differences. For the M-ADA stimuli synesthetes had significantly less fusion responses (answer D, synesthesia: 22.4% ± 35.3%; control: 46.6% ± 39.7%; two sided t-test, p < .05). Synesthetes thus perceived ‘ADA’ less often and their answer was driven mainly by the auditory information (answer B, synesthesia: 75.6% ± 38.3%; control: 52.1% ± 40%). The visually driven answer G was very rare in both groups (synesthesia: 2% ± 8.2%; control: 1.3% ± 5.8%). The calculation of 2 × 4 × 2 repeated measurement ANOVA (STIMULATION, SNR, GROUP) for the outer conditions revealed an effect of STIMULATION [F(1, 26) = 179.5, p < .001], SNR [F(3, 78) = 2433.0, p < .001] and an interaction of SNR and STIMULATION [F(3, 78) = 53.1, p < .001]. No differences between groups can be detected in the outer conditions indicating similar audiovisual processing in both groups for these SNRs.