As I understand it, the hypodermic syringe model would not help us describe stereotypes in movies. Instead, it would help us understand the impact of those stereotypes on the audiences.
The hypodermic syringe model would argue that any stereotypes portrayed in movies would be received and internalized by audiences.
For example, this model would argue that kids would watch a movie that portrays women as weak and would automatically believe that message.
By this understanding, stereotypes in the movies are very pernicious because they will be internalized and believed by the audiences, thus perpetuating the stereotypes.
This "Hypodermic Syringe Model" would help to imply that the mass media have a huge and direct impact on the role as a audience. It would have a powerful influence on the people tonging the cinemas nowadays. It has a critical impact to the humans' behavior and human's perception on stereotypes portrayed in the movies. There have been many factors that cause this model of communication to uprise, mainly due to the advancement of technology, the invention of radios, computers and television that can be found right in your doorstep. Also, the mass insurgence of propaganda tactics and advertisements would provide a monopolizing effect and brainwashing tool on human's minds and control their actions in whatever they do. This tool of mind-control has been practice in many countries in the past, most notably Russia and Germany, who use them to control the whole empire and gain the people's trust and respect.
This model shows out how people mind works. Their mind and soul are controlled by biologically hidden instincts, and they would react upon any stimulus that had crossed their way. They would believe what the movie had sent across into their mind, the hidden message or the main theme of the plot, making them seem vulnerable and susceptible to manipulation. This technique can been seen on war-propaganda films that Nazi Army like to use before the war to grow his army.