The group dinner effect
You arrive at the restaurant planning to order a main course and water. Then:
Someone suggests “apps for the table”
The first person orders a cocktail, so you get one too
Someone mentions the ribeye looks good, and suddenly your chicken seems boring
Dessert menus arrive. You’re full, but three people are ordering
The check comes. It’s $89. You planned for $35
This isn’t weak willpower. It’s social facilitation, one of the most robust findings in behavioral psychology. The presence of other people fundamentally changes how much we consume.
The 44% effect: de Castro’s discovery
In 1990, psychologist John de Castro at Georgia State University asked a simple question: does eating with others change how much we eat? He had participants keep detailed food diaries, recording what they ate, when, and crucially, with whom.
The results were striking. Meals eaten with other people were 44% larger than meals eaten alone. This wasn’t about restaurant portions or special occasions. It held true across breakfast, lunch, and dinner. At home and at restaurants. On weekdays and weekends.
de Castro and Brewer’s 1992 meta-analysis confirmed the finding: the more people at the meal, the more everyone eats. The relationship was linear. Two people meant more consumption than one. Seven people meant more than four.
This is called social facilitation of eating. The presence of others doesn’t just influence what we eat. It fundamentally changes how much we eat. And at restaurants, where meals are priced per item, eating more means spending more.
Source: de Castro, Journal of Personality and Social Psychology, 1990; de Castro & Brewer, Physiology & Behavior, 1992
Social mirroring: why you order what they order
Beyond eating more, groups also influence what we order through a phenomenon called social modeling. Psychologists C. Peter Herman, Janet Polivy, and Patricia Pliner documented this in their 2003 research on social influences on eating.
The mechanism is simple: we look to others for cues about appropriate behavior. When someone orders an appetizer, it signals that appetizers are “normal” for this meal. When they order dessert, it creates social permission for dessert.
This creates a cascade effect. The first orderer sets an anchor. Each subsequent person either matches or exceeds that anchor to avoid appearing cheap, different, or unsophisticated. The effect is especially pronounced at girls night dinners, where cocktail rounds and shared plates amplify social matching to its extreme.
“When we don’t know what to do, we look to others. In the restaurant context, ‘what to order’ becomes a social signaling game where matching the group often beats optimizing for personal preference.”
C. Peter Herman, Handbook of Clinical Nutrition, 2003
Source: Herman, Polivy & Pliner, Handbook of Clinical Nutrition, 2003
Menu anchoring: how the first order warps everyone’s choices
Behavioral economists Dan Ariely and Jonathan Levav studied this ordering cascade in their 2000 paper “Sequential Choice in Group Settings.” Their finding: order position matters enormously.
When people order sequentially (as they do at most restaurants), the first person’s choice becomes an anchor. Later orderers are unconsciously influenced by what came before, but they also want to appear unique. This creates a bizarre tension.
The uniqueness paradox: Diners want to fit in (ordering similarly to others) but also stand out (not ordering the exact same thing). This drives people toward “unique” choices that are often more expensive, adventurous dishes they wouldn’t have considered ordering first.
The result is systematic overspending. People order dishes they’re less satisfied with, at prices they wouldn’t have paid, because they’re optimizing for social perception rather than personal preference.
Source: Ariely & Levav, Journal of Consumer Research, 2000
Anticipated regret: the FOMO mechanism
Economist Robert Cialdini’s work on social proof explains part of the group ordering effect. But there’s another force at work: anticipated regret.
Loomes and Sugden formalized this concept in 1982. The idea: we don’t just evaluate choices by their outcomes. We also consider how we’ll feel if we don’t choose something and it turns out great. This is the psychological foundation of FOMO.
”I should have ordered that. Why didn’t I?”
”They’re all enjoying it. I’m just sitting here.”
”If I don’t get one, I’ll be the odd one out.”
”When will I be back? I should try it.”
Przybylski and colleagues’ 2013 study on FOMO confirmed its power: people with higher FOMO tendencies consistently spent more in social situations, experienced more post-purchase regret, and were more susceptible to impulse purchases triggered by others’ behavior.
At the dinner table, anticipated regret manifests as: “If I don’t order this and everyone else loves theirs, I’ll wish I had.” The irony is that people report higher satisfaction with their meal when they order based on personal preference, not social pressure.
Source: Loomes & Sugden, Economic Journal, 1982; Przybylski et al., Computers in Human Behavior, 2013
The equal split multiplier
All of these effects compound when the group expects to split the bill equally. Uri Gneezy, Ernan Haruvy, and Hadas Yafe documented this in their landmark 2004 study.
When diners knew they’d split equally, they ordered 37% more than when paying for their own items. The reasoning is rational: if I order a $15 salad and you order a $45 steak, and we split evenly, I’m subsidizing your meal. Better to order the steak too.
The FOMO spending equation:
Social facilitation (+44%) + Social mirroring (+18%) + Equal split incentive (+37%)
= Compound overspending that can exceed 100% of what you’d spend dining alone
The effects aren’t simply additive, they interact. Social facilitation makes you hungrier. Social mirroring points you toward more expensive items. The equal split expectation removes the financial brake. Together, they can more than double your restaurant spending compared to dining alone.
Source: Gneezy, Haruvy & Yafe, The Economic Journal, 2004
Why it’s so hard to resist
You might think awareness would help. It doesn’t, much. Solomon Asch’s famous conformity experiments from the 1950s showed that people conform to group behavior even when they know the group is wrong.
In Asch’s experiments, participants matched obviously incorrect answers 37% of the time when facing a unanimous group. The discomfort of being the only dissenter was stronger than the confidence of being right.
The same dynamics apply at dinner. Even if you planned to order a salad, being the only one not ordering an entree feels socially costly. The fear of standing out, of being judged as cheap or antisocial, overrides rational budget preferences. For people-pleasers, this pressure is even stronger—they’ll conform to the group’s spending level rather than risk the mildest disapproval.
But notice that third statistic. When just one other person broke from the group, conformity dropped from 37% to 5%. Having an ally changes everything.
Source: Asch, Psychological Monographs, 1956
Five evidence-based strategies to prevent FOMO spending
The research points to specific interventions that actually work. Here’s what the science suggests:
Order first
Ariely's research shows the first orderer is least susceptible to social anchoring. They set the anchor instead of being influenced by it. If you want to stick to your plan, order before others can influence you.
Set a mental budget before you see the menu
Prelec and Loewenstein’s work on payment pain shows that pre-commitment reduces overspending. Decide “I’m spending $40 tonight” before you open the menu. This creates an internal anchor that competes with social anchors.
Find an ally
Asch's conformity research proves that one dissenter dramatically reduces conformity pressure. If you and one friend both plan to skip appetizers, the social cost of sticking to your plan drops by 85%.
Use itemized splitting
When you know you’ll pay for what you order, the equal-split incentive disappears. Gneezy’s research shows itemized payment reduces overspending to near-solo levels. splitty makes this automatic.
Reframe FOMO as regret insurance
The anticipated regret of not ordering something fades quickly. The regret of overspending lingers. Remind yourself: you're not missing out by ordering what you actually want. You're avoiding the regret of spending $50 you didn't plan to spend.
Designing against FOMO spending
splitty is built with these behavioral insights in mind. Here’s how the research translates to design:
The goal isn’t to make you spend less. It’s to make you spend what you intended to spend. When itemized splitting is effortless, the FOMO spending incentives disappear. You can order the salad without subsidizing the ribeye.
