Audio-haptic cue integration across the lifespan

Optimal integration of multisensory information has frequently been shown to benefit perception by speeding up responses and increasing perceptual precision and accuracy. These effects, however, are often demonstrated in young adults, and to a lesser extent in older adults or children, with a scarcity of studies examining how optimal integration changes across the lifespan. Furthermore, most studies have used different tasks and approaches to measure multisensory processing adaptation over large age ranges, making it difficult to compare between them. Here, by using the same adaptive size discrimination task and a cross-sectional design, we investigated how audio-haptic cue integration performance changes over the lifespan in children, younger adults, and older adults (age range spanning from 7 to 70years). Participants were asked to give size discrimination judgements for physical objects of different sizes using either touch or hearing (unimodal) or both at the same time (bimodal). Discrimination thresholds were assessed for unimodal and bimodal stimulus presentation and compared with predictions from a maximum likelihood estimation (MLE) model. Results show that children do not make use of audio-haptic multisensory size information until around 13 years of age, while both younger and older adults benefit from integrating multisensory information, leading to increased precision. These results corroborate and extend the findings from previous studies that used different approaches, showing that children only gain from multisensory integration late in childhood, but that its benefits are preserved until later in life. It further suggests that integration of non-visual information, which becomes increasingly important with declining visual function later in life, allows individuals to effectively make use of redundant information, thereby offering an advantageous compensatory mechanism for declining sensory function.