Temporal metrics of multisensory processing change in the elderly

Abstract Older adults exhibit greater multisensory response time (RT) facilitation by violating the race model more than younger 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 are farther from true simultaneity as compared to younger 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 younger and older adults in order to better understand the underlying mechanisms that subserve audiovisual multisensory temporal processing. Our results confirm previous reports showing that audiovisual RT, TBWs and PSSs change with age, and we show for the first time a significant positive relation between the magnitude of race model violation in younger adults as a function of the PSS obtained from the audiovisual TOJ task with (r: 0.49, p: 0.007), that is absent among the elderly (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 younger (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) there is evidence for distinct neural networks involved in simultaneity and temporal order perception; and iii) common processing between race model violation and temporal order judgment is impaired in the elderly.