In this video I explain the concept of internal validity and how it acts as a checklist for considering whether an independent variable has been effectively manipulated, a dependent variable has been measured without bias, and a clear pattern can … Read More
Observer Bias: Clever Horses and Dull Rats
In this video, I explain two well-known examples of observer bias: the case of Clever Hans, and Rosenthal and Fode’s experiment with “bright” and “dull” rats. Observer bias (or experimenter expectancy effect) is considered, along with an explanation for how … Read More
Was Hans really Clever?
Here’s a good video summary of the case of Clever Hans and how Oskar Pfungst was able to figure out that Wilhelm von Osten was inadvertently signaling answers to Hans. And even though Hans wasn’t actually doing mathematics, he was … Read More