In a field study, we collected data in a restaurant and manipulated bite size by providing diners with small or large forks. We found that diners consumed more from smaller rather than larger forks. Utilizing motivation literature, which ties into the unique factors present in a restaurant consumption setting (e.g., diners have a well-defined goal of hunger satiation because they invest effort by visiting a specific restaurant, choose from a menu, and pay money for the meal), we present our rationale for the pattern of results.
Sounds pretty obvious, right. Small forks cue Big eating since each bite is Small. Big forks cue Small eating since each bite is Big. Easy-peesey. Here’s a graph to illustrate.

And, this is not a trivial effect.
We assessed the influence of fork size on the weight of the food left on the plate (less food on the plate indicated more consumption) while controlling for the weight of the initial food served, food price, meal occasion (lunch vs. dinner), appetizer (yes vs. no) and alcohol consumption (yes vs. no). This ANCOVA showed that the use of the larger fork resulted in more food left on the plate (i.e., less quantity consumed) than the smaller fork (Mlarge = 7.91 ounces vs. Msmall = 4.43 ounces; F(1, 98) = 7.80, p < .01, partial η2 = .07).
That η2 (eta squared) of .07 translates into a Small+ Windowpane, about 40/60 which would probably be obvious to an observant observer who was looking for an effect. Thus, if you were a dishwasher for this restaurant, you could probably see the difference on the amount of food left on plates between the Small and Big fork conditions. Hey, 4 ounces versus 8 ounces is a lot of spagetti and meatballs.
So the Small fork causes people to eat more because each bite is too small and so they take more bites and more food. The Big fork actually has the effect of reducing caloric consumption. Cue up the Food Police! If we can put calorie counts on menus why not fork size specifications!
Except.
Moreover, in a controlled lab study we demonstrate that when these factors are absent, the pattern of results is reversed.
What? Reversed? Yes. And practical, too.
Using ANCOVA, we assessed the influence of fork size on the weight of pasta left on the plate while controlling for the initial weight of the pasta served. The results showed that those assigned to the large fork condition left less pasta in the bowl (i.e., consumed more pasta) than those in the smaller fork condition (Mlarge = 4.09 ounces vs. Msmall = 5.19 ounces; F(1, 78) = 4.73, p < .03, partial η2 = .05).
This eta squared is another Small+ Windowpane, about a 40/60 difference. And again, someone who was really looking could probably see the practical difference here as in our sweaty dishwasher cleaning up the plates.
Small forks cue Small eating? Didn’t the first study report Big forks cue Small eating? What the hell is going on here? Which is it? A fork is a fork, right? The Food Police are not happy. Cancel that march on the White House.
This is a cross over interaction where a relationship is positive under one condition then negative under another condition. Stated another way, it depends. Stated under persuasion labels, the play depends upon the box or what’s the Local?
The trick here is the motivational set of the eater. In the first study with Small Fork, Big Eats:
In our consumption context, we observe that diners visit the restaurant with a well-defined goal of satiating their hunger, and, because of this well-defined goal, they are willing to invest effort and resources to satiate their hunger. Since research has shown that free choice captures realistic behavior more accurately than forced choice situations (Dhar and Simonson 2003), a restaurant offers diners several methods to exercise free choice in satiating their hunger. For instance, diners select a restaurant of their choice, choose an entrée (or entrées) from the menu of offerings, pay for their food, and have the option to take home leftovers. Therefore, people invest effort in order to satiate their hunger.
When the Other Guy has the goal of Satisfying Hunger, then we get Small Forks, Big Eats. But, in the second study with Small Fork, Small Eats:
Eighty-one participants took part in this study for partial course credit. They were told that this was a food consumption study, and each participant was taken to a separate table. They were then offered a preweighted bowl of pasta salad with either a small or a large fork and a bottle of water. The same forks from the restaurant study were used. A pasta salad was served, since several bites are required for consumption rather than a single forkful. Participants were left alone and allowed to consume as much as they wanted.
When the Other Guy has the goal of fulfilling the requirements of a study, we get Small Forks, Small Eats. The effect of fork size depends upon why the Other Guy is using the fork. For Hungry Other Guys fork size means something different than for UnHungry Other Guys doing a marketing study.
Mavens, understand persuasion by the function of a variable, not its structure, content, or appearance. How, not What. You can always spot the amateur on this play. Understand the function or how the thing does what it does, not what it is. See the difference between Doing and Being.
Wow. Philosophical Persuasion Theory!
More entertaining is the Cool Table media comment on this article. You can read the NYT, WSJ, Huffington Post, and Time for their details, but here’s the main point: They missed the main point! Each media comment on this study catches only the first study with Small Forks and Big Eats and completely misses the functional truth of the cross over interaction. Those Cool Table players drop their maven masks to reveal muggle mugs underneath. They each and all think Small Forks, Big Eats, so buy a Bigger Fork to lose weight!
Want to join the Cool Table? Carry a Big Fork and Eat Softly.
Want to Change the Other Guys eating? Determine Their goal, then fork them appropriately.
It Depends!
All Persuasion Is Local.
Arul Mishra, Himanshu Mishra and Tamara M. Masters. (2012). The Influence of Bite Size on Quantity of Food Consumed: A Field Study. Journal of Consumer Research , Vol. 38, No. 5, pp. 791-795
DOI: 10.1086/660838