pinky up –> "I’ll promise" "I’ll keep promise"
index finger up –> "one"
thumb up –> "great"
References :

There is even an article about consumerism in WIKIPEDIA the free encyclopedia:
http://en.wikipedia.org/wiki/Consumerism

P.S.
I think your teacher gave you a very difficult homework. Me, as a grown-up I would have difficulties to answer it, because you have to know Japanese culture very well, and one would need some statistics to prove certain behavior of the consumers.
References :

I knew anime drew me in, but what I think made me stay was the art & fluid mentatlity behind it. It can be quietly, beautifully traditional one minute, then the next it’s a spazztically loud, crazy, spectacle. I think their general ability to flow between the past (taking time to appreciate nature & the beauty in little, imperfect things) & the future (striving for the newest, fastest, sleekest, most effecient technology possible) impresses me the most, because that’s something we Americans tend struggle with.

And it’s not just in art or culture, either – average citizens do this every day, and they do it so well that, even though they’re traditional, Japan still manages to be on the cutting edge almost everything. But what impesses me even more is that they like to do these things quietly; they don’t brag, show off, or get all in your face about it. Plus, I am an absolute FIEND for their style of art & animation, so that helps
References :
Long-time Japanophile