COLUMBUS, Ohio – A new study from The Ohio State University suggests that people’s perceptions of the steepness of hills are significantly influenced by their height and the angle of their gaze. This research, published in the journal Perception, reveals that individuals consistently overestimate the steepness of hills, regardless of their visual orientation.
The study, led by Dennis Shaffer, a professor of psychology at Ohio State’s Mansfield campus, aimed to explore the reasons behind these perceptual distortions and how altering a person’s gaze might affect their perception. “If you’re driving toward a hill that you see in the distance, it typically looks a lot steeper from far away than when you get right on it,” Shaffer explained. “Part of that is because of the way you’re looking at it, you’re changing your gaze relative to the object.”
Understanding Perceptual Distortions
In the first experiment, researchers tested 36 participants’ ability to estimate the slant of a wooden ramp while lying down or sitting on a yoga mat. Participants were asked to estimate the orientation of four slopes from approximately seven feet away. A second experiment examined how eye height affects perception by having participants stand on the third rung of a step ladder or sit cross-legged on a yoga mat while estimating the slope.
“In general, people overestimate the slopes of surfaces by a factor of 1.5, so most people would estimate a 30-degree hill to be 45 degrees,” Shaffer noted. The study found that individuals overestimated slopes more when the distance between their eye height and the slope’s surface was reduced. This effect was more pronounced when participants were seated compared to standing on the ladder, and even more so when lying down.
Implications of Eye Height on Perception
According to Shaffer, these findings confirm long-standing theories about slope perception. “One of our lab’s superpowers is finding interesting methodologies to get at the questions we’re interested in,” he said. “In doing so in this study, we saw a lot of our and others’ predictions pan out.”
Previous research had struggled to establish a clear link between slope perception and eye height. However, this study explored a broader range of slopes and observer eye heights than previous studies, revealing a significant negative correlation between eye height and slant estimates. Brooke Hill, a co-author and undergraduate student at Ohio State Mansfield, explained, “Shorter individuals tended to predict ramp orientations to be steeper than taller individuals would.”
“We don’t realize that as humans, perception is everything,” Hill stated. “Gaining better insight into how our gaze changes our worldview is also a step toward improving systems used for road safety, GPS navigation, vehicle design, and other assistive technologies.”
Future Research and Applications
Looking ahead, Shaffer and his team plan to further explore how different vantage points and methods influence an individual’s gaze and perception. This research aims to uncover how unique environmental perspectives shape our collective understanding of the world. “Humans are really good pattern-seekers,” Shaffer said. “But by teaching people about head orientation and what it does for their perception of different things, we can help them keep a steadier version of what the world looks like.”
The study’s findings have practical implications, particularly in fields such as road safety and vehicle design, where understanding perception can lead to improved systems and technologies. Montse Juarez, another undergraduate co-author, contributed to this research, highlighting the collaborative effort behind these insights.
For further information, contact Dennis Shaffer at [email protected].
Written by Tatyana Woodall, [email protected]
