Which example best illustrates a self-serving bias?

• A. A student attributing good grades to his own abilities and blaming a tough professor for bad grades
• B. A student blaming the professor for good grades
• C. A student attributing good grades to luck
• D. A student attributing bad grades to external factors

Answer: (B)

Self-serving bias shows up when people take credit for their successes and blame external factors for their failures. The best illustration is a student who says good grades come from his own abilities while blaming a tough professor for the bad grades. That combination—internal attribution for success and external attribution for failure—is exactly what self-serving bias looks like. The other patterns don’t fit as neatly: blaming the professor for good grades assigns the success to someone else; attributing good grades to luck treats success as an outside factor; and blaming external factors for bad grades shows external blame for failure but doesn’t pair it with taking credit for success.