Is technical analysis somehow a valid method for investment? I personally think technical analysis (TA) is not useful at all but I still see lot of courses about technical analysis, and even people using it.  They have the advantage of being easy to learn and they claim themselves as following the "behavioral economics" theory.

Is the traditional &amp; simple TA somehow valid?  I'm asking about the one that uses moving averages, graphs, momentum lines to try to predict market moves.  

The behavioral economics theory is valid and 2 people won Nobel prizes because of that, so I'm not arguing its validity, but its consequences or usefulness as an investment method.

Please take into account not only a highly efficient market (eg, the US), but other smaller and less efficient markets (I'm from Argentina).
The Lo, Mamaysky and Wang paper Foundations of Technical Analysis: Computational Algorithms, Statistical Inference, and Empirical Implementation is probably the best investigation of this question. He found there were some patterns that seemed to be useful, notably the Head and Shoulders pattern.