Sean's Ramblings

Thoughts on life, technology, and anything else that catches my interest.

Responsibility: How Does Your Guide Dog Know When to Cross the Street

This blog isn’t dead yet. Life has been hectic lately (I was told that I need to start taking more responsibility for my research), so I haven’t had a lot of time to write. For this post, I thought I would talk about a non-technical topic that I love, and many people don’t seem to understand. As mentioned in previous posts, I have a guide dog named Simba. He is a yellow lab, and about 2.5 years old. I received him from Guide Dogs for the Blind, more specifically their campus in California. One of the things that I’ve found is people have the general idea that a guide dog helps a blind person get around, but most people aren’t clear on the responsibilities of the human handler, and the responsibilities of the guide dog. In this post, I’m going to explain it to the best of my understanding, which may or may not match a given guide dog school’s policy, or the opinion of another handler.

So, let’s start by setting an example scene. It’s early in the morning, and I walk into Engineering Building II (the Computer Science building) on North Carolina State University’s campus. I head down the hall towards my class which starts in five minutes. Someone has left a table in the middle of the hall, so we (Simba and I) swerve around it. We continue down the hall, and make a left into the fourth side hallway. We approach the classroom door, and proceed inside. In this example, who was responsible for what actions?

When explaining my working relationship with my dog to people, I often use the analogy of a navigator and a pilot on an airplane. I am the navigator, responsible for the general direction and overall route, while Simba is the pilot, and responsible for picking the path in the local environment and obstacle avoidance. Applying that to the example given above, I instructed Simba to go down the hallway, while Simba decided the best path to take to avoid the table. I determined when to signal Simba to turn left, while Simba looked around, and took me down what he thought was the first available path in the direction that I had indicated (he did not count the hallways on the left, or anything like that). Finally, I instructed Simba to find the classroom door, and he took me to the first door that he saw.

In order to perform his actions, Simba needs to understand what I’m asking for, and needs to be able to do basic object recognition. When I signal left, he needs to perform the thought process that I probably don’t mean make a hard left into the wall, but to walk forward and turn left at the first point of interest, whether that is a hallway, door, etc. That also means that Simba has to be capable of recognizing various objects, such as doors, benches, elevators, etc. In fact, he does know these objects, so I can give him the command “Simba, find the x,” where x is an object that has been taught to him.

This allows me as a blind person to do things that a cane could never do. For example, today I had to wait in a building’s lobby for someone that I was meeting with. Keeping in mind that I have never been in this area before, I had no information about the layout or contents of the room. If I wanted to take a seat rather than standing around, and I had a cane, I would have to methodically search the room for somewhere to sit. It wouldn’t be a completely dumb search, since I can apply heuristics based on my experience to check the more likely areas first, but it would have taken time, and looked somewhat strange to an observer. Since I had Simba, I could say “Simba, find the chair.” Based on his response, whether it was enthusiastic or hesitant, I could tell if a chair was within line-of-sight. Since Simba started moving immediately and confidently, I followed him, and he took me directly to a chair. Now even novel environments are not a problem because of my guide dog.

There is a few circumstances where Simba will decide to take immediate action without my prompting, and that is typically when safety is a concern. While Simba is an extremely well trained dog, he has no desire to be hit by something such as a car or door. When something unexpectedly moves towards him, he will move out of the path to protect both of us. This is why handlers need to completely trust their dog, and unhesitatingly follow when their dog makes a sudden movement. Simba has had to do this a couple times with me when drivers weren’t paying attention, and almost hit us with their car. In addition, Simba has been taught “intelligent disobedience”, which is the idea that Simba can disobey a command if he judges something unsafe. If I give the forward command when there is a large drop in front of us, or a road with significant traffic, Simba may decide not to follow that command. This is a safety feature for the times when I am unaware of danger when making my decisions. This leads to one of the most common questions that I get asked, which is, “How does Simba know when to cross the street.” The simple answer is that he doesn’t, I do. It is up to me as the handler to decide when we move forward, and then Simba takes the shortest path to the other side. Simba does not read the traffic, nor does he look for the green light, nor does he listen to the audio signals (the chirping sound found in some intersections). It is completely up to the handler to use their experience and judgment to decide when to cross a street.

In summary, I as the handler decide where and when to go, where as Simba simply (or not so simply) decides the path to take to fulfill my request. He has to be smart, since he has to plan paths around obstacles, and recognize objects in the environment. He also has to evaluate when to quickly move out of the way of an object, and when to ignore my commands when I am putting us in significant danger. Lastly, it’s worth mentioning that since Simba and other guide dogs like him are so clever, they do pay attention to where they are going, and will learn routes or places we visit frequently. This means that after walking a route a few times, Simba will figure out where I’m probably trying to go, and will just lead me there without any prompts. This has saved me a few times when I became confused and lost when going to a classroom, and Simba was able to take charge, and lead me to class (gee, thanks there buddy).

Sean