Previous studies have found that semantics, the higher-level meaning of stimuli, can impact multisensory integration; however, less is known about the effect of valence, an affective response to stimuli. This study investigated the effects of both semantic congruency and valence of non-speech audiovisual stimuli on multisensory integration via response time (RT) and temporal-order judgement (TOJ) tasks [assessing processing speed (RT), Point of Subjective Simultaneity (PSS), and time window when multisensory stimuli are likely to be perceived as simultaneous (temporal binding window; TBW)]. Through an online study with 40 participants (mean age: 26.25 years; females = 17), we found that both congruence and valence had a significant main effect on RT (congruency and positive valence decrease RT) and an interaction effect (congruent/positive valence condition being significantly faster than all others). For TOJ, there was a significant main effect of valence and a significant interaction effect where positive valence (compared to negative valence) and the congruent/positive condition (compared to all other conditions) required visual stimuli to be presented significantly earlier than auditory stimuli to be perceived as simultaneous. A subsequent analysis showed a positive correlation between TBW width and RT (as TBW widens, RT increases) for the categories that were furthest from true simultaneity in their PSS (Congruent/Positive and Incongruent/Negative). This study provides new evidence that supports previous research on semantic congruency and presents a novel incorporation of valence into behavioural responses.
Older adults exhibit greater multisensory response time (RT) facilitation by violating the race model more than young adults; this is commonly interpreted as an enhancement in perception. Older adults typically exhibit wider temporal binding windows (TBWs) and points of subjective simultaneity (PSS) that typically lie farther from true simultaneity as compared to young adults when simultaneity judgment (SJ) and temporal-order judgment (TOJ) tasks are utilized; this is commonly interpreted as an impairment in perception. Here we explore the relation between the three tasks in order to better assess audiovisual multisensory temporal processing in both young and older adults. Our results confirm previous reports showing that audiovisual RT, TBWs and PSSs change with age; however, we show for the first time a significant positive relation between the magnitude of race model violation in young adults as a function of the PSS obtained from the audiovisual TOJ task (r: 0.49, p: 0.007), that is absent in older adults (r: 0.13, p: 0.58). Furthermore, we find no evidence for the relation between race model violation as a function of the PSS obtained from the audiovisual SJ task in both young (r: −0.01, p: 0.94) and older adults (r: 0.1, p: 0.66). Our results confirm previous reports that (i) audiovisual temporal processing changes with age; (ii) distinct processes are likely involved in simultaneity and temporal-order perception; and (iii) common processing between race model violation and temporal-order judgment is impaired in the elderly.