Abstract:

Along with aging, older adults often experience a significant deterioration in their vision and hearing. Single-channel visual training can enhance older adults' perception of texture features, direction discrimination, contrast sensitivity, stereovision sensitivity, and to some extent, it can also transfer to untrained cognitive abilities such as visual working memory and attention. However, there are drawbacks, including the limited variety of training materials and tasks, as well as incomplete research on the neural mechanisms underlying the transfer of visual training. Single-channel auditory training can enhance older adults' speech perception and recognition, compensating for the decline in their ability to perceive speech in noisy backgrounds and improving their deteriorating auditory abilities. However, it is still uncertain how much training is required to induce changes in older adults' auditory abilities and other aspects, and the transfer effects of auditory training on untrained cognitive functions are relatively limited. Moreover, older adults are exposed to more multimodal stimuli in their daily lives compared to single-modal stimuli, but research has not demonstrated that single-channel visual or auditory training can enhance cross-channel perceptual abilities in older adults. In a word, single-channel perceptual training has relatively limited improvement of cognitive ability in older adults.

Studies have revealed that audiovisual cross-modal interactions have a compensatory and facilitative effect in alleviating the declining perceptual ability of older adults in single modalities. Compared to single-channel training, audiovisual training has shown to be more effective in improving perceptual training efficiency in older adults. Thus, researchers have conducted perceptual training for older adults using a cross-modal approach that leverages the promotion and compensation of information across visual and auditory channels. This approach aims to investigate the effects of such training on improving cognitive abilities in older adults. The simultaneity judgment task and temporal order judgment task are commonly used training paradigms in studies related to cross-modal temporal perception training in older adults. Audiovisual perceptual training in older adults primarily focuses on audiovisual sensitivity, namely the audiovisual temporal binding window. The results indicate that audiovisual perceptual training significantly narrows the temporal binding window in older adults, providing advantages in improving their perceptual discrimination sensitivity. Audiovisual perceptual training enhanced the brain’s neural processing efficiency for audiovisual stimuli, highlighting the advantages of cross-modal training. It even shows potential in enhancing cognitive functions in older adults with mild cognitive impairment (MCI). However, researches predominantly center on audiovisual sensitivity at present, specifically the temporal binding window. There is a shortage of studies targeting the enhancement of audiovisual integration ability, particularly in terms of adaptive compensatory effects in older adults.

In future research, it can be further explored from the following objectives. Firstly, the formulation of precise and efficient audiovisual perceptual training programs, directed towards the targeted enhancement of audiovisual integration abilities, and the elucidation of neural mechanisms underlying compensatory effects in older adults. Secondly, large-scale experiments are to be conducted for a comprehensive examination of key factors contributing to individual variations in training effects. Furthermore, the implementation of long-term training intervention will serve to investigate the population-specificity and durability of these training effects. Thirdly, an exploration of the interplay between brain functionality in healthy older adults and training intensity and duration, with a specific focus on the relevance of intervention load to brain function, is warranted. Additionally, there is a need to probe into the effect of audiovisual perceptual training on integration abilities and transfer effects in individuals afflicted with neurodegenerative diseases. These endeavors are poised to establish a robust scientific framework and furnish novel perspectives for the advancement of perceptual intervention products, thereby bearing profound practical implications for the amelioration of cognitive functions and the overall physical and mental well-being in older adults.

Key words: perceptual training, older adults, audiovisual integration, facilitative effect, targeted enhancement