Bandwagon
This technique is usually used to persuade people to join something that other people are apart of. The poster above is telling you that the woman in the photo makes bombs but she is also supporting the war by buying war bonds. The poster is trying to convince the audience to do what the poster says.
Transfer
This technique is used to add a positive light to a product or the provider of a product. In this WPA poster, the market is shedding positive qualities about itself in the way that the storekeeper buys the food brings the food to the store so you can come and buy it. The poster is wanting you to come to the market and buy the products there because the storekeeper is the one who supplies everything.
Testimonial
This technique is used to persuade the viewer to buy the product that is being endorsed by a famous person. In the advertisement Jessica Simpson is endorsing Proactiv Skincare, this should persuade the viewer to buy the product because she uses it so they should use it too.