A drawing of an old woman. The interesting part of the story of this figure is that it was used in a psychology experiment at Columbia University. Half of the class were given one of the figures, half the other. Then the figures were collected and the entire class shown the ambiguous figure. In subsequent class discussion, those who had seen one of the figures had great difficulty in seeing the second possibility, even when it was described in detail by someone in the other half of the class.
Students often have a similar difficulty in a physics class.
If they have already misinterpreted previously given knowledge or previous experience, it may be very difficult for them to put the correct interpretation on what a teacher says. The fact that this problem is widespread and occurs in many areas of an introductory physics class has been well documented in the physics education literature. This is by now very well documented by a large number of psychological studies. Some students respond better to visual information, others to symbology. There are many variables, and a good knowledge of physics requires calling on a wide variety of different media and manners of coding and conveying information.