Role of stereopsis losses in older adults’ performance on the fine-grain movement illusion task

Accurate motion perception is necessary for older adults to safely navigate their environments. Yet it is not clear how stereopsis losses contribute to findings of motion perception deficits in older adults. To assess the contribution of stereopsis losses, three groups (younger adults, older adults with intact stereopsis, older adults with poor stereopsis) were recruited for a fine-grain movement task. The distance participants perceived a dot to move across a computer screen was assessed using a staircase procedure. While all participants perceived the dot to move further than the actual distance, older adults with poor stereopsis showed more exaggeration in their estimates than younger adults and older adults with intact stereopsis. However, the groups did not differ in the intraindividual variability of their estimates. These results suggest stereopsis losses in the context of aging may signal neural or oculomotor changes that result in reduced accuracy of positional perception.