Contra-freeloading: Something that every psychologist, neuroscientist, economist, and policymaker should know about

Why do people work?  For the money, obviously.  That’s a fundamental part of how most people think about economics.

Why do rats and monkeys press levers in experiments on reinforcement learning? Because pressing the lever produces food or water, obviously. That’s a fundamental part of how most psychologists and neuroscientists think about reinforcement learning.

If people or animals could get money/food without working for it, they would never work. In other words, everyone would be a freeloader given the chance. Right?

Wrong. Studies going back to 1963 show that animals will push buttons and press levers to get food even if they have easy access to a container of equivalent food. What? Given the opportunity to freeload, animals will still work?  That’s crazy!  But it’s true.  Humans will also work for candy or coins in the presence of free candy or coins. This is called “contra-freeloading” because it’s the opposite of freeloading.

Allen Neuringer

Allen Neuringer

I first heard about contra-freeloading from one of my undergrad mentors at Reed CollegeAllen Neuringer, who published one of the first papers on it in Science in 1969. The title of the paper beautifully captures the central finding: “Animals respond for food in the presence of free food.” This provocative paper—published in one of the most widely read scientific journals—has been cited by other researchers fewer than 300 times in the 50 years since it was published. Responding for food in the presence of free food has since been observed in species ranging from pigeons and rats to giraffes, parrots, and monkeys, but most psychologists and neuroscientists are completely unaware of this phenomenon. (Interestingly, cats appear to be an exception; they will work for food only if there is no other choice. Cats are nature’s freeloaders.)

One theory is that contra-freeloading occurs because it helps organisms gain information about the environment that might be useful later. If you know that pressing a lever gets you food, this might come in handy if other sources of food disappear. This does not seem like a very compelling explanation, however, because (under some conditions) animals will respond at a very high rate to get food in the presence of free food. It’s not like they’re just checking to see if the lever still works from time to time. (See also this elegant study showing that monkeys will work to get information about the size of the next reinforcer, even though this has no impact on whether they will get the reinforcer and gives them no long-term information.)

Contra-freeloading seems like an important phenomenon for economists and policymakers: People don’t just work for money, and they are not inevitably freeloaders. Sure, people will often freeload when given the chance. But the factors that motivate human behavior are far more complex than a simple desire to maximize income.

Contra-freeloading is also important for psychologists and neuroscientists: Organisms are not motivated solely by gaining rewards and avoiding punishments. If we want to understand the neural mechanisms underlying behavior, we cannot simply focus on explicit rewards and punishments.

I occasionally hear psychologists and especially behavioral neuroscientists say something along the lines of: “All learned behavior is controlled by reinforcement. The reinforcer may be nonobvious, but it’s there.  After all, why else would an organism do something?” But this is a completely circular argument: “We see that an organism is pressing a lever, so it must be getting some kind of reinforcer.” (For experts: the Premack principle can sometimes be used to avoid this circularity, but it does not explain why an animal would respond for food in the presence of free food.)

An economist might try a parallel move, saying that people try to maximize “utility” and not just income (where “utility” is essentially “whatever someone thinks is valuable”). But this is also a circular argument: “We see that people are working, so they must be getting something of value for their work.” In other words, when people work without getting paid, we assume that they must be getting something else they find valuable (some kind of utility). But this is usually just an assumption and is typically unfalsifiable. Does this assumption really add anything to our explanation of human behavior, or is it just a soup stone

To understand contra-freeloading, we need to make a distinction between “responding because of reinforcement” and “responding to obtain the reinforcer.” When pressing a lever produces food, a rat will press the lever. Rats don’t press levers just because they enjoy lever pressing (just as I don’t go to work because I enjoy spending my days answering endless emails). If the lever stops producing food, the rat will stop pressing the lever. Allen Neuringer’s 1969 article showed that rats and pigeons will respond for food in the presence of free food, but they will stop responding if they stop getting food for their responses. Curiously, they are responding because the lever produces food, but not because they need the food. It’s as if they are responding so that they can have the experience of producing food, not just to get the food itself.

By analogy, most people would probably quit their jobs if they stopped getting paid, but this does not mean that people work solely to get paid. First, they need the paycheck—they’re not like rats who are responding for food in the presence of free food. A more analogous situation would be people who keep working after they win the lottery. Or retirees with good pensions who go back to work even though they don’t really need the money. We can attempt to explain unpaid work by saying that people must be trying to obtain some other kind of reinforcer, but this is circular and doesn’t actually explain anything.

The idea that money and other overt reinforcers are the best way to motivate human behavior can have some unpleasant consequences. When CEOs are given strong financial incentives to maximize share prices, this incentivizes them to inflate short-term share prices rather than working to maximize long-term value. When scientists are given promotions and salary increases when they publish papers in prestigious journals, this incentivizes them to engage in p-hacking and other questionable research practices.

But this doesn’t mean we can ignore incentives. Although rats will press a lever to get food in the presence of free food, they will stop pressing the lever if it stops producing food. That seems completely counterintuitive: If the rats don’t need the food, why do they press the lever only if it produces food?

Motivation is both vexingly and wonderfully complicated!

Classic Article: "Features and Objects in Visual Processing" by Anne Treisman

Treisman, A. (1986). Features and objects in visual processing. Scientific American, 255, 114-125.


I read this article—a review of the then-new feature integration theory—early in my first year of grad school.  It totally changed my life.  My first real experiment in grad school was an ERP version of the "circles and lollies" experiment shown in the attached image:

Luck, S. J., & Hillyard, S. A. (1990). Electrophysiological evidence for parallel and serial processing during visual search. Perception & Psychophysics, 48, 603-617.

In that experiment, I discovered the N2pc component (because I followed some smart advice from Steve Hillyard about including event codes that indicated whether the target was in the left or right visual field).  I've ended up publishing dozens of N2pc papers over the years (along with at least 100 N2pc papers by other labs).

The theory presented in this Scientific American paper was also one of the inspirations for my first study of visual working memory:

Luck, S. J., & Vogel, E. K. (1997). The capacity of visual working memory for features and conjunctions. Nature, 390, 279-281.

As you may know, Anne passed away recently (see NY Times obituary).  Anne was my most important scientific role model (other than my official mentors).  I'm sure she had no idea how much impact she had on me. She probably thought that I was an idiot, because I became a blathering fool anytime I was in her presence (even after I had moved on from grad student to new assistant professor and then to senior faculty).  But her intelligence and creativity just turned me to jello...

Anyway, this is a great paper, and very easy to read.  I recommend it to anyone who is interested in visual cognition.