About the study

Audio-visual temporal illusions, such as the Sound-Induced Flash Illusion (SIFI), provide a useful tool for probing cross-modal influences on early visual processing.  A tactile analogue, the Touch-Induced Flash Illusion (TIFI), has also been observed, yet the relationship between these illusions within the same individuals, and how it may vary across the lifespan, remains largely unexplored.

In the present study, seventy-six younger and seventy-six older adults completed both the SIFI and TIFI paradigm remotely, via mobile phone devices. Age-related differences in illusion susceptibility were dependent on task: older adults showed greater susceptibility than younger adults in the SIFI but not the TIFI. SIFI and TIFI also showed different illusion profiles: SIFI elicited more fusion than fission illusions, whereas illusion type did not differ in TIFI. Cross-task consistency was high: individuals more susceptible to the TIFI were also more susceptible to the SIFI. Despite modality-specific ageing effects and differing illusion profiles, we interpret both patterns as explainable by similar integration principles. Specifically, whilst temporal coding of auditory signals was more reliable than vision, temporal coding of tactile signals appeared less reliable. As such, both increased ageing effects in SIFI and age-equivalent effects in TIFI may still reflect appropriate adjustments in sensory weighting across the lifespan. This study provides the first demonstration of SIFI and TIFI measured in a remote testing framework, within the same individuals, in younger and older adults, offering new insight into how multisensory integration evolves across the lifespan.

What we measure