In 1968, psychologists Robert Rosenthal and Lenore Jacobson walked into an elementary school in San Francisco with a devious plan.
They told teachers they had developed a new test that could predict which students were “intellectual bloomers”—kids on the verge of rapid intellectual growth.
They administered the test, then gave teachers a list of students who supposedly scored highest. These students, they said, would show remarkable gains in IQ over the coming year.
The teachers were excited. Finally, they could identify the high-potential kids and watch them soar.
There was just one problem.
The test was fake. The “bloomers” were chosen completely at random.
The Twist
Eight months later, Rosenthal and Jacobson returned to test the students again.
The results were shocking.
The randomly selected “bloomers” showed significantly higher IQ gains than their classmates—especially in younger grades, where some students gained 20+ IQ points.
But how? These weren’t actually gifted students. They were average kids chosen by random chance.
The only thing that changed was the teachers’ expectations.
The teachers believed these students were special. They treated them differently—more warmth, more feedback, more challenging questions, more opportunities.
And the students became what the teachers expected.
What Is the Pygmalion Effect?
The Pygmalion Effect (also called the Rosenthal Effect) is the phenomenon where higher expectations lead to increased performance.
When someone believes you’re capable of more, you often rise to meet those expectations—even if there’s no initial difference in ability.
It’s a self-fulfilling prophecy, but a positive one.
Named after the Greek myth of Pygmalion, a sculptor who fell in love with his statue and brought it to life through his belief in it.
Modern Examples
1. Military Leadership
- Israel Defense Forces study: Trainees told their instructor had “high expectations” performed better
- Same trainees, same training—different expectations
- Result: Higher test scores, better performance reviews
2. Sports Performance
- Coaches told certain players had “high potential” (randomly selected)
- Those players received more playing time, more coaching attention
- Result: They improved more than teammates
3. Employee Performance
- Managers told certain employees were “high performers” (random)
- Those employees received more mentorship, better projects
- Result: Higher performance reviews, faster promotions
4. Medical Outcomes
- Doctors told some patients “respond very well to this treatment”
- Result: Better outcomes, even with identical treatments (placebo on steroids)
Why It Happens
The Pygmalion Effect works through subtle behavioral changes:
Teachers/Leaders Change Their Behavior:
- Climate - Warmer emotional tone, more smiles, more eye contact
- Input - More challenging material, higher-level questions
- Opportunity - More chances to respond, lead, contribute
- Feedback - More detailed feedback, more encouragement
Students/Employees Respond:
- Confidence - “They believe in me, so I can do this”
- Effort - More motivation to meet high expectations
- Risk-Taking - Willing to try harder problems
- Persistence - Don’t give up as quickly
It’s a feedback loop. Higher expectations → better treatment → improved performance → confirmed expectations → even higher expectations.
In Software Engineering
The Pygmalion Effect is everywhere in tech:
Junior Developer Trajectory
Scenario A: "Junior devs need constant supervision"
Result: They're given trivial tasks, never grow
Scenario B: "This junior is sharp, they'll pick it up fast"
Result: Given real challenges, mentorship, they excel
Same developer, different expectations, different outcome
Code Review Dynamics
Low Expectation: "This person writes buggy code"
Behavior: Nitpick everything, harsh comments
Result: Developer becomes defensive, slower
High Expectation: "This person is thoughtful"
Behavior: Constructive feedback, ask good questions
Result: Developer improves, writes better code
Interview Bias
"This candidate went to Stanford, must be good"
Result: Softball questions, friendly demeanor, hired
"This candidate is from unknown school"
Result: Harder questions, skeptical tone, rejected
Same skills, different expectations, different outcomes
Team Performance
Manager thinks: "This team is rockstars"
Behavior: Trusts them, gives autonomy, resources
Result: Team delivers
Manager thinks: "This team is struggling"
Behavior: Micromanages, questions everything
Result: Team morale tanks, delivery slows
How to Harness the Pygmalion Effect
1. Assume Capability
Default to believing people can rise to challenges.
- ❌ “They’re not ready for that”
- ✅ “Let’s give them support and see what they can do”
2. Communicate High Expectations
Tell people you believe in them. Explicitly.
"I'm giving you this project because I think you can handle it."
"I've seen your growth—you're ready for more responsibility."
3. Provide Stretch Opportunities
Don’t protect people from challenge. Challenge is how they grow.
- Junior devs: Let them own features, not just tickets
- New managers: Give them real decisions
- New hires: Trust them with important work
4. Give High-Quality Feedback
High expectations without feedback is abandonment.
Not: "Good job" (vague)
But: "You handled that edge case brilliantly. The way you
structured the error handling shows real growth."
5. Watch for the Golem Effect
The Pygmalion Effect has an evil twin: The Golem Effect—low expectations lead to worse performance.
If you believe someone will fail, they probably will. Not because they’re incapable, but because you’ll unconsciously sabotage them.
6. Audit Your Assumptions
Who do you have high expectations for? Why? Who do you have low expectations for? Why?
Are your expectations based on evidence, or bias?
- Pedigree bias (fancy school = smart)
- Similarity bias (like me = good)
- Recency bias (recent mistake = bad)
The Dark Side
The Pygmalion Effect isn’t always positive.
It can reinforce existing biases:
- Teachers expect more from students who look like them
- Managers promote people who remind them of themselves
- Interviewers hire candidates from “good” schools
It can create pressure:
- Students crack under unrealistic expectations
- Employees burn out trying to meet impossible standards
It can ignore genuine limitations:
- Not everyone can be a “10x engineer”
- High expectations don’t fix systemic issues
The key is calibrated high expectations—believing in potential while providing support.
The Deeper Lesson
The Pygmalion Effect reveals something profound: we become who others believe we are.
Those elementary school students didn’t magically get smarter. The test was random. But the teachers’ belief in them made them smarter.
Your expectations aren’t neutral. They’re active forces shaping reality.
When you treat someone like they’re capable, creative, and trustworthy—they often become exactly that.
When you treat someone like they’re incompetent, lazy, or untrustworthy—they’ll meet those expectations too.
The Programmer’s Perspective
As engineers, we love to think we’re objective. We measure, we test, we rely on data.
But managing people isn’t like debugging code. Your beliefs change the system you’re measuring.
Think about:
- The junior dev you didn’t give challenging work to (did they stagnate, or did you never give them a chance?)
- The teammate whose PRs you scrutinize heavily (are they writing worse code, or are you finding problems because you expect to?)
- The new hire you “have doubts about” (are they struggling, or are you unconsciously withholding support?)
You might be creating the outcomes you fear.
Expectations are code that runs on human hardware. Write them carefully.
Key Takeaways
- ✅ Higher expectations lead to higher performance
- ✅ Teachers/leaders unconsciously change behavior based on expectations
- ✅ People rise (or fall) to meet the expectations set for them
- ✅ Communicate belief in people explicitly
- ✅ Watch for bias in who gets high vs low expectations
Rosenthal’s students weren’t special. Until someone believed they were.
The next time you’re about to write someone off as “not ready” or “not good enough,” remember those randomly selected elementary school students who gained 20 IQ points.
The only difference was someone believed in them.
What would happen if you believed in the people around you?