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Interview with Dr. Jeffrey Wagman

Jeffrey B. Wagman, Ph.D. is Professor of Psychology at Illinois State University. His research focuses on perception of affordances. He is a recipient of the Illinois State University Outstanding University Researcher Award and a Japan Society for the Promotion of Science Invitation Fellowship for Research in Japan. He is an Associate Editor of the journal Ecological Psychology and a co-editor of the Resources for Ecological Psychology Book series. To learn more about his work, visit this page:

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Avidnote Podcast: In today’s episode, we look at research that attempts to answer the old childhood riddle. What weighs more, a pound of lead or a pound of feathers? Now this question may seem like it has a straightforward, almost trivial answer They obviously weigh the same, but the answer is actually not that simple.

NASA: Ignition sequence start, four, three, two, one. Lift off!

The year was 1971 and NASA astronauts were on their way to the moon. This was the fourth time humanity would set foot on the moon. The following is a clip from that mission.

Avidnote Podcast: The person speaking is commander David Scott. He’s standing on the surface of the moon.

Dave Scott: Well, in my left hand, I have a feather, in my right hand, a hammer. And I guess one of the reasons we got here today was because of a gentleman named Galileo a long time ago, who made a rather significant discovery about falling objects and gravity fields. And we thought that, where would be a better place to confirm his findings than on the moon.

Avidnote Podcast: Commander Scott is holding a feather in one hand and a hammer in the other.

He then proceeds to drop them at the same time and against our intuition and against everything that we perceive to be normal. The two objects fall exactly at the same time, confirming what we’ve known for centuries. That objects fall at the same rate, regardless of their mass.

This doesn’t happen here on earth, of course, due to the presence of air resistance, the feather would fall at a slower pace compared to the hammer due to the air that’s keeping it up. We’re used to this and expect this to be the result. But what happens when our senses betray us? What happens when common sense fails has predicting reality, not on the moon, but here on earth?

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Abderisak: This episode, I speak with Professor Jeffrey Wagman about his paper entitled “Which Feels Heavier, a Pound of Lead or a Pound of Feathers?” As a Professor of Psychology at Illinois State One of his research interests pertains to the perception of affordances. Now, I don’t know about you, but this term was completely new to me.

 I’ll let Professor Wagman explain

Dr. Jeffrey Wagman: We go about our day doing hundreds of behaviors, thousands of behaviors. I’m interested in the everyday successes of our interactions with the world, the reaching and grasping of coffee cups, the steering of your car, the passing through traffic, the stepping out of the way of a pedestrian.

All of those things require your perceptual systems to cooperate with your movement systems. And that’s really what I do. I try to understand the extraordinary success of everyday behavior and an affordance is a possibility for behavior. So , perceiving that an object is graspable or throwable or step-on-able

Avidnote Podcast: Step-on-able, that’s an interesting word. Essentially, what Professor Wagman does is to explore the world around us and how we interact with it, the things we grasp and how we manipulate them and how that’s connected to our own perception. The term affordance was originally coined in the mid 1960s by American Psychologist, James Gibson, but the concept was known and studied much earlier.

 Affordances offer a direct link between perception and action. They’re essentially action possibilities afforded by the environment to us. So for example, a chair, uh, affords you to sit on it. We say that it’s seatable.

 But then there’s another type of affordance, which I personally find to be more interesting and which is much more hidden. In fact, it’s called a hidden affordance.

Eddie Murphy: Anybody got them mothers that would hit you with her shoe, I had a mother that would throw a shoe at you at the drop of a dime and [bleep] you up wherever she was aiming,

Avidnote Podcast: That’s Eddie Murphy speaking from his 1983 standup special Delirious.

Eddie Murphy: She would like carry that shit like a gun. By the time I was like 10, my mother was like Clint Eastwood with it. And you [bleep], up my mother, walked in the room was like,

Avidnote Podcast: What he’s describing here is a perfect example of what’s referred to as a hidden affordance. The shoe in this example has besides the obvious use as something that you wear, which is easily perceivable as such. It also has a hidden functionality, in this case, as a throwable weapon.

So now that we’ve discussed what affordances are, let’s get back to Professor Wagman or Jeff, as he prefers to be called.  When thinking about my conversation with him, I’m reminded of that old quote by the American writer and actress, Lilly Tomson, who once said,  I like a teacher who gives you something to take home to think about besides homework. Professor Wagman strikes me as that type of character. He likes to reflect and think about his surroundings and draws inspiration from his everyday interactions for his own research. I asked him if he ever wanted to shut that part off. The constant imagining and viewing the world through the prism of Psychology, his own research and years of experience, his answer did surprise me a bit.

Dr. Jeffrey Wagman: I think one of the really wonderful things about being an academic and maybe you feel this way too. Is that you don’t want to shut that up. For most people in a nine to five job, they can’t wait to go home. And when they are home, they are done. And anything else they do when they clock out, it’s their time.

But for me, it’s not just what I do, it’s who I am. And I think a lot of academics feel that way. So I’m always thinking about stuff. I get research ideas walking around and just watching people.

Avidnote Podcast: So the reason why we’re talking with Professor Wagman is due to a research paper that he wrote a few years ago. The paper in question was authored by Wagman together with Zimmerman and Sorric in 2007 published in the Journal “Perception”.

The abstract is a breath of fresh air  in that it’s written in a clear and easy to understand style  that perfectly encapsulates the study and its results.  It reads:  which weighs more, a pound of lead or a pound of feathers.  The seemingly naive answer to this familiar riddle is the pound of lead. The correct answer of course, is that they weigh the same amount.

 We investigated whether the naive answer to the riddle might have a basis in perception. When blindfolded participants  hefted a pound of lead and a pound of feathers, each contained in boxes of identical size, shape, and mass, they reported that the box containing the pound of lead felt heavier at a level above chance.

The study is basically saying, if you carry a box of metal and then you carry a box of equal weight filled with feathers, you will on average say that the box filled with metal weighs heavier, even though the mass is exactly the same. So with that in mind, why does this study show this peculiar result and have others talked about this before?

Why do people on average judge the box containing metal as heavier, even though they weigh exactly the same? To answer this, we first need to understand the size weight-illusion.

Dr. Jeffrey Wagman: It’s this idea that two objects of the same mass can feel unequally heavy depending on their volume, depending on how that mass is distributed. It’s a little bit counterintuitive, but the idea is that the mass that is more compact feels heavy. You might imagine, a billiard ball that is maybe the same weight as some rubber ball, but the billiard ball, might feel heavier.  It’s counterintuitive that the smaller object feels heavier, but it really has to do with the way the mass is distributed. So, we’ve known about this illusion for over a hundred years and,  in the lab I came out of as a graduate student, had done a lot of work on perception by touch.  

And they developed mathematical models to show that it has to do with the rotational inertia. Which is really just how much force you need to apply to rotate an object against the pull of gravity, it’s related to torque. But the idea is that. You have to apply forces, to put an object into motion and to stop an object as it’s moving.

And in doing that, you’re generating forces in different directions and the more unique, the set of forces that you need to put in different directions, the heavier an object feels. All of the things being equal. If you have to put lots of force in one direction and then wow wow wow pull it back.

And then wow wow wow, pull it back But if that object would feel heavier than an object of the same mass that you just need to put the same amount of force in each direction to keep it moving and stop it moving. So we knew that. That’s not a discovery that I made. It’s a discovery that people at the university of Connecticut made in the 1990s and early 2000s.

And to me hearing about that research made me think a lot about this children’s riddle.  The riddle is what weighs more? A pound of lead, or a pound of feathers? And of course you fool a person into saying, oh, well, it’s a pound of lead. And then we say, ha ha, you got it wrong. And I began to think, well, huh.

I mean, yeah.  It’s wrong in a sense because they don’t weigh the same, but why would a person say that? What would lead them to make the error?  And I began to think about, take that phenomenon and connect it up with this research. That two objects of the same mass can feel unequally heavy. And I said, that’s what this is! Because you’ve got this compact mass, a pound of led and this more diffuse mass, a pound of feathers, and maybe.

It’s that they’re sort of thinking about the forces that would be required to manipulate these type of two objects. It was a bit of a leap, but I thought, I need to know this. I need to know if these two objects actually feel different because if they do, then maybe the error is not really an error. It’s not a mistake in reasoning.

 It’s something different.

Avidnote Podcast: I then asked him whether some people are immune to this illusion, or if it’s just part of being a human that you’re susceptible to it

Dr. Jeffrey Wagman: So that’s a really good question.

It would have to do with experience, and context specific experience because the way I think about perception. Perception is, a lawful process, just like any other lawful process in the universe. And so the principles that underlie that are the same for you and me, but that doesn’t mean that you can’t become sharper, more attuned to these lawful relationships.

 It’s a matter of expertise, but it’s not that, I guess I want to be clear that the expert is not perceiving. They don’t become less immune to the illusion because they are becoming better calculators. Right. It’s a different metaphor here, they’re becoming better measurement devices.

Avidnote Podcast: So you may be wondering, how big is this difference exactly? Is it difficult to tell?

Dr. Jeffrey Wagman:

It’s really subtle. It kind of comes down when you ask people to do this. That’s why, if you look at the results of this study, so the study is, where I put a pound of lead. Really, I’m not sure it’s actually, lead, but like metal pellets in a bag and it’s put that bag in a box. And then in another box I put a pound of feathers and they both end up weighing the same by a balanced scale.

 When you ask people to heft one and then another. You asked them, which one of these feels heavier? And you do this many, many times, it’s not clear when they do this, they don’t have a very clear impression. They feel like they’re guessing. And it’s also, they don’t reliably pick one over the other, but they pick the one that has the lead, the metal beads in it just a little bit more often. Like 6 out of 10 times, but 6 out of 10 times over enough people is better than guessing.

 It’s statistically significant. They’re not just guessing. It is strange though.

When you do pick up these, if you say, I don’t know, um, this one. It’s very subtle. If you really pay attention to how it feels. It’s, that’s just one has a subtle rock to it. Meaning, you know, it has an axis to it. And the other one doesn’t cause it’s diffuse. Once you realize what you’re holding, then you say, oh, oh, I see . This one, I have to sort of rock to keep it steady. And this one I don’t have to, but the movements are so subtle.

Avidnote Podcast: Finally, I then asked whether or not we can train ourselves to become immune to this illusion. Is this something that we can attune our senses to with extended experience and training?

Dr. Jeffrey Wagman: Yeah, I think so. It’s just about, attuning that ability. By the same argument, there are people in my field who argue that everybody reads lips.

You probably have had an experience where you’re having dinner with someone in a noisy restaurant, and you realize that you understand them better.

If you look at it. And if you look away, you can still understand it, but it requires a little bit more attention. So the point is, everybody reads lips. It’s not just people who are impaired, who need to, it’s the people who are impaired and need to who have sort of elevated that ability. And that becomes an important way that they can understand speech.

So everybody has this, everybody’s sort of a superhero in a sense, You know, you hear about someone who makes noises and listens to the reflections, and that helps them guide their behavior. And they sound like a superhero and in some sense they are, but you know, that’s, that is everybody does it.

Avidnote Podcast: Everybody is a superhero of sorts. I think that’s a great way to end today’s episode. A quick thanks to our guest, Dr. Jeffrey Wagman for taking his time to talk to us. All the best.

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