Patricia DeLucia has spent much of her career investigating a question that rarely reaches conscious awareness but is fundamental to everyday safety: how people judge whether a collision is about to occur. These judgements underpin countless routine actions, from catching a ball to crossing a busy road. For DeLucia, now a professor of psychological sciences, this research interest has personal roots that extend back to her childhood, long before she entered academia.
Growing up, DeLucia was deeply involved in sport, an environment where accurately anticipating collisions is essential. On the field, she constantly assessed whether a ball was coming towards her, whether another player was about to make contact, and whether there was enough time to react. At the time, these judgements felt intuitive rather than analytical. Only later did she realise that these early experiences had shaped the questions that would define her scientific work, turning instinctive reactions into objects of systematic study.
That long-standing curiosity eventually led DeLucia to focus on collision judgments made by people with visual impairment, particularly individuals with age-related macular degeneration, a condition that affects central vision. Despite the apparent importance of collision perception for activities such as navigating streets or crowded environments, relatively little research has examined how visual impairment influences these abilities. DeLucia’s work aims to address this gap by exploring not only performance differences but also how people adapt to changes in sensory input.
In a recent study published in PLOS One, DeLucia and her collaborators used a sophisticated virtual reality system to examine how adults with and without macular degeneration estimate the arrival time of an approaching vehicle. Participants experienced realistic simulations in which a car approached along a road and then disappeared. The system combined visual displays with authentic vehicle sounds, allowing the researchers to present sight alone, sound alone, or both together. Participants indicated when they believed the vehicle would have reached them by pressing a button. The study involved a multidisciplinary team across the United States and Europe and was supported by funding from the National Eye Institute.
The researchers were particularly interested in whether people with impaired vision rely more heavily on sound, and whether combining sight and sound improves accuracy. They expected that individuals with macular degeneration would still use their remaining vision rather than depend entirely on auditory cues. The results were striking: participants with macular degeneration performed very similarly to those with normal vision when estimating vehicle arrival times. Although they appeared to rely more on less precise cues, their overall performance was comparable. Even with impaired central vision, participants continued to use visual information and integrated it with available auditory information.
When vision or sound was presented alone, both groups showed perceptual biases observed in earlier studies. Louder vehicles were judged to arrive sooner than quieter ones, and larger vehicles were judged to arrive sooner than smaller ones. These heuristic shortcuts appeared slightly more often in the macular degeneration group, but the differences were minor. Contrary to expectations, having both vision and sound did not improve accuracy for either group, suggesting that multisensory input does not always confer an advantage.
DeLucia emphasises that clinical measures such as visual acuity do not always predict real-world functioning. However, she cautions that the findings are based on simplified virtual scenarios and do not imply that people with visual impairment can navigate real traffic environments as safely as those without impairment. Still, she hopes the research will inform future work on mobility, rehabilitation and safety, ultimately helping to enhance independence for people with visual impairment.
More information: Patricia DeLucia et al, Visual, auditory, and audiovisual time-to-collision estimation among participants with age-related macular degeneration compared to a normal-vision group: The TTC-AMD study, PLOS One. DOI: 10.1007/s00394-023-03123-x
Journal information: PLOS One Provided by Rice University
