Holmström’s (1982/99) career concerns model has become an important workhorse for theanalysis of agency issues in many fields. The underlying signal jamming argument requiresplayers to use information in a Bayesian way – which may or may not reasonablyapproximate real-life decision makers’ behavior. Testing this theory with field data is difficultsince typically little is known about the information that individuals base their decisions on,and this explains the dearth of empirical studies. We provide experimental evidence that thesignal jamming mechanism works in a laboratory setting. Moreover, subjects' beliefs fitremarkably well requirements imposed by the Bayesian equilibrium concept.