The Visual Cliff

The Importance of the Integrated Collapsible/Retractable Sides on our Lightweight Portable Ramp for Domestic Pet Dogs, by Brian Douglas

A common, but largely unrecognized, phenomenon affecting the lives of countless pet dogs and their owners is the aversion to the perceived “visual cliff.” A behavior that can be reliably observed in puppies as young as 28 days old (Handbook of Applied Dog Behavior and Training, Steven R. Lindsay, p. 275), it causes extreme avoidance behavior in dogs (as well as humans, cows and almost all other animals) when faced with a perceived risk of falling. In simple terms, most dogs are hard-wired to avoid differences in elevation - and the risks associated with falling off of them - at all costs.

In humans, the “heart rate quickens, eyes widen and breathing rate increases.” (Campos, et al., 1978). In cows, the response was equally strong:  “Heifers in the depth-exposed group showed a higher heart rate (p < .05) and stopped more often (p < .05) than did those in the control group…These results indicate that heifers responded differently to a change in depth than they did to a standard change in the environment and provide evidence of both depth perception and acute fear of heights…”  (Arnold, et al., 2007).

The most compelling synthesis of the visual cliff comes from bestselling author and eminent researcher Temple Grandin. In a lecture given at the 35th International Congress of the International Society of Applied Ethology in Davis, California, in 2001, she provided real-world evidence of the primacy and power of the visual cliff in even the most stressful environments when she discussed her findings of cattle behavior in a slaughterhouse. 

Upon entering the facility the animals were faced with a conveyor system intended to move them through the slaughter process.  “A solid false floor was added to prevent the animals from seeing the ‘visual cliff’ effect as they entered the restrainer… (but)…animals would often refuse to enter if they could see the steep drop off.  The false floor provided the optical illusion of a solid floor to walk on.” She then adds:  “Cattle remained calm and entered the restrainer easily when the vision blocking panels were installed. Prior to the installation of the false floor and solid roof the cattle often became extremely agitated.” She found that a strategically placed “piece of cardboard instantly made 450 kg cattle become calm.” 

Grandin’s findings illustrate that, in spite of being in the midst of all the sights, sounds and smells of a slaughterhouse, elimination of the visual cliff alone made the enormous animals calm. In fact, she lists elimination of the visual cliff as one of the five most important behavioral principles that make the animals remain behaviorally calm (Grandin, 2001). Dogs and cows both share strong aversions to the visual cliff at an early age and - without proper desensitization training or handling techniques - both carry this aversion through adulthood. While extensive inventive and commercial efforts have addressed this issue in livestock, nothing lightweight and/or portable exists for dogs and other companion animals.

This realization, combined with our repeated exposure to ramp-averse dogs in our professional lives, led us to begin investigating the problem – and potential solutions – in earnest. Our research confirmed that approaches similar to those that ameliorate this fear in cattle do the same in dogs. Initial testing revealed that – when presented with a novel ramp – over 85% of dogs refused to use it. When we applied vision-blocking Cliff-Stop Technology™ to the ramp, 85% of the group that initially refused proceeded to use it without fear.

In our experience, domestic pet dogs exhibiting aversion to the visual cliff stimulus in real world applications (ramps, stairs, examination tables, grooming tables & lifts, and edges of various types) often simultaneously exhibit fear responses and avoidance (fight-or-flight) behaviors. Those observed included panting, crouching, pulling away, seeking an alternate route around or under the stimulus and, in many cases, complete immobility (learned helplessness) or jumping off the elevation to avoid using the ramp. These anxiety responses present challenges to the pet handler and real dangers to the pet, especially when managing the elderly, disabled and mobility-challenged. By simply incorporating vision blocking sides into our ramp, we eliminate these dangers, as well as what we consider to be the primary reason dogs won’t use ramps. There’s nothing like it on the market today, and it’s the only ramp in existence that reduces apprehension in dogs while simultaneously encouraging them to use it.

To protect and make proprietary this concept, our utility patent is written to capture such use on any and all lightweight portable applications for domestic pets, including ramps, stairs, grooming and examination tables and lifts. It is in non-provisional pending status, with the benefit of an initial provisional application filing date of September 7, 2011.


Arnold, N.A., et al.  Responses of dairy heifers to the visual cliff formed by a herringbone milking pit: Evidence of fear of heights in cows (Bos Taurus).  Journal of Comparative Psychology, Vol 121(4), Nov. 2007.

Campos, J.J., et al. (1978). The emergence of fear on the visual cliff. In Michael Lewis and Leonard A. Rosenblum (Eds.). The development of affect. New York: Plenum.

Grandin, Temple. Transferring results of behavioral research to industry to improve animal welfare on the farm, ranch and the slaughter plant. D.G.M. Wood-Gush Memorial Lecture. 35th International Congress of the International Society of Applied Ethology. Davis, California. 2001.